diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index b198b827d0c2f..50ea133eb670c 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -3987,6 +3987,19 @@ namespace ts {
             return getIndexTypeOfStructuredType(getApparentType(type), kind);
         }
 
+        function getImplicitIndexTypeOfType(type: Type, kind: IndexKind): Type {
+            if (isObjectLiteralType(type)) {
+                const propTypes: Type[] = [];
+                for (const prop of getPropertiesOfType(type)) {
+                    if (kind === IndexKind.String || isNumericLiteralName(prop.name)) {
+                        propTypes.push(getTypeOfSymbol(prop));
+                    }
+                }
+                return getUnionType(propTypes);
+            }
+            return undefined;
+        }
+
         function getTypeParametersFromJSDocTemplate(declaration: SignatureDeclaration): TypeParameter[] {
             if (declaration.flags & NodeFlags.JavaScriptFile) {
                 const templateTag = getJSDocTemplateTag(declaration);
@@ -5747,9 +5760,9 @@ namespace ts {
                         if (result) {
                             result &= signaturesRelatedTo(source, target, SignatureKind.Construct, reportErrors);
                             if (result) {
-                                result &= stringIndexTypesRelatedTo(source, originalSource, target, reportErrors);
+                                result &= indexTypesRelatedTo(source, originalSource, target, IndexKind.String, reportErrors);
                                 if (result) {
-                                    result &= numberIndexTypesRelatedTo(source, originalSource, target, reportErrors);
+                                    result &= indexTypesRelatedTo(source, originalSource, target, IndexKind.Number, reportErrors);
                                 }
                             }
                         }
@@ -5951,76 +5964,65 @@ namespace ts {
                 return result;
             }
 
-            function stringIndexTypesRelatedTo(source: Type, originalSource: Type, target: Type, reportErrors: boolean): Ternary {
-                if (relation === identityRelation) {
-                    return indexTypesIdenticalTo(IndexKind.String, source, target);
-                }
-                const targetInfo = getIndexInfoOfType(target, IndexKind.String);
-                if (targetInfo) {
-                    if ((targetInfo.type.flags & TypeFlags.Any) && !(originalSource.flags & TypeFlags.Primitive)) {
-                        // non-primitive assignment to any is always allowed, eg
-                        //   `var x: { [index: string]: any } = { property: 12 };`
-                        return Ternary.True;
-                    }
-                    const sourceInfo = getIndexInfoOfType(source, IndexKind.String);
-                    if (!sourceInfo) {
-                        if (reportErrors) {
-                            reportError(Diagnostics.Index_signature_is_missing_in_type_0, typeToString(source));
-                        }
-                        return Ternary.False;
-                    }
-                    const related = isRelatedTo(sourceInfo.type, targetInfo.type, reportErrors);
-                    if (!related) {
-                        if (reportErrors) {
-                            reportError(Diagnostics.Index_signatures_are_incompatible);
+            function eachPropertyRelatedTo(source: Type, target: Type, kind: IndexKind, reportErrors: boolean): Ternary {
+                let result = Ternary.True;
+                for (const prop of getPropertiesOfObjectType(source)) {
+                    if (kind === IndexKind.String || isNumericLiteralName(prop.name)) {
+                        const related = isRelatedTo(getTypeOfSymbol(prop), target, reportErrors);
+                        if (!related) {
+                            if (reportErrors) {
+                                reportError(Diagnostics.Property_0_is_incompatible_with_index_signature, symbolToString(prop));
+                            }
+                            return Ternary.False;
                         }
-                        return Ternary.False;
+                        result &= related;
                     }
-                    return related;
                 }
-                return Ternary.True;
+                return result;
             }
 
-            function numberIndexTypesRelatedTo(source: Type, originalSource: Type, target: Type, reportErrors: boolean): Ternary {
+            function indexInfoRelatedTo(sourceInfo: IndexInfo, targetInfo: IndexInfo, reportErrors: boolean) {
+                const related = isRelatedTo(sourceInfo.type, targetInfo.type, reportErrors);
+                if (!related && reportErrors) {
+                    reportError(Diagnostics.Index_signatures_are_incompatible);
+                }
+                return related;
+            }
+
+            function indexTypesRelatedTo(source: Type, originalSource: Type, target: Type, kind: IndexKind, reportErrors: boolean) {
                 if (relation === identityRelation) {
-                    return indexTypesIdenticalTo(IndexKind.Number, source, target);
-                }
-                const targetInfo = getIndexInfoOfType(target, IndexKind.Number);
-                if (targetInfo) {
-                    if ((targetInfo.type.flags & TypeFlags.Any) && !(originalSource.flags & TypeFlags.Primitive)) {
-                        // non-primitive assignment to any is always allowed, eg
-                        //   `var x: { [index: number]: any } = { property: 12 };`
-                        return Ternary.True;
-                    }
-                    const sourceStringInfo = getIndexInfoOfType(source, IndexKind.String);
-                    const sourceNumberInfo = getIndexInfoOfType(source, IndexKind.Number);
-                    if (!(sourceStringInfo || sourceNumberInfo)) {
-                        if (reportErrors) {
-                            reportError(Diagnostics.Index_signature_is_missing_in_type_0, typeToString(source));
+                    return indexTypesIdenticalTo(source, target, kind);
+                }
+                const targetInfo = getIndexInfoOfType(target, kind);
+                if (!targetInfo || ((targetInfo.type.flags & TypeFlags.Any) && !(originalSource.flags & TypeFlags.Primitive))) {
+                    // Index signature of type any permits assignment from everything but primitives
+                    return Ternary.True;
+                }
+                const sourceInfo = getIndexInfoOfType(source, kind) ||
+                    kind === IndexKind.Number && getIndexInfoOfType(source, IndexKind.String);
+                if (sourceInfo) {
+                    return indexInfoRelatedTo(sourceInfo, targetInfo, reportErrors);
+                }
+                if (isObjectLiteralType(source)) {
+                    let related = Ternary.True;
+                    if (kind === IndexKind.String) {
+                        const sourceNumberInfo = getIndexInfoOfType(source, IndexKind.Number);
+                        if (sourceNumberInfo) {
+                            related = indexInfoRelatedTo(sourceNumberInfo, targetInfo, reportErrors);
                         }
-                        return Ternary.False;
                     }
-                    let related: Ternary;
-                    if (sourceStringInfo && sourceNumberInfo) {
-                        // If we know for sure we're testing both string and numeric index types then only report errors from the second one
-                        related = isRelatedTo(sourceStringInfo.type, targetInfo.type, /*reportErrors*/ false) ||
-                            isRelatedTo(sourceNumberInfo.type, targetInfo.type, reportErrors);
-                    }
-                    else {
-                        related = isRelatedTo((sourceStringInfo || sourceNumberInfo).type, targetInfo.type, reportErrors);
-                    }
-                    if (!related) {
-                        if (reportErrors) {
-                            reportError(Diagnostics.Index_signatures_are_incompatible);
-                        }
-                        return Ternary.False;
+                    if (related) {
+                        related &= eachPropertyRelatedTo(source, targetInfo.type, kind, reportErrors);
                     }
                     return related;
                 }
-                return Ternary.True;
+                if (reportErrors) {
+                    reportError(Diagnostics.Index_signature_is_missing_in_type_0, typeToString(source));
+                }
+                return Ternary.False;
             }
 
-            function indexTypesIdenticalTo(indexKind: IndexKind, source: Type, target: Type): Ternary {
+            function indexTypesIdenticalTo(source: Type, target: Type, indexKind: IndexKind): Ternary {
                 const targetInfo = getIndexInfoOfType(target, indexKind);
                 const sourceInfo = getIndexInfoOfType(source, indexKind);
                 if (!sourceInfo && !targetInfo) {
@@ -6263,6 +6265,16 @@ namespace ts {
             return !!(type.flags & TypeFlags.Tuple);
         }
 
+        /**
+         * Return true if type was inferred from an object literal or written as an object type literal
+         * with no call or construct signatures.
+         */
+        function isObjectLiteralType(type: Type) {
+            return type.symbol && (type.symbol.flags & (SymbolFlags.ObjectLiteral | SymbolFlags.TypeLiteral)) !== 0 &&
+                getSignaturesOfType(type, SignatureKind.Call).length === 0 &&
+                getSignaturesOfType(type, SignatureKind.Construct).length === 0;
+        }
+
         function getRegularTypeOfObjectLiteral(type: Type): Type {
             if (type.flags & TypeFlags.FreshObjectLiteral) {
                 let regularType = (<FreshObjectLiteralType>type).regularType;
@@ -6610,9 +6622,7 @@ namespace ts {
                         inferFromProperties(source, target);
                         inferFromSignatures(source, target, SignatureKind.Call);
                         inferFromSignatures(source, target, SignatureKind.Construct);
-                        inferFromIndexTypes(source, target, IndexKind.String, IndexKind.String);
-                        inferFromIndexTypes(source, target, IndexKind.Number, IndexKind.Number);
-                        inferFromIndexTypes(source, target, IndexKind.String, IndexKind.Number);
+                        inferFromIndexTypes(source, target);
                         depth--;
                     }
                 }
@@ -6644,12 +6654,22 @@ namespace ts {
                 inferFromTypes(getReturnTypeOfSignature(source), getReturnTypeOfSignature(target));
             }
 
-            function inferFromIndexTypes(source: Type, target: Type, sourceKind: IndexKind, targetKind: IndexKind) {
-                const targetIndexType = getIndexTypeOfType(target, targetKind);
-                if (targetIndexType) {
-                    const sourceIndexType = getIndexTypeOfType(source, sourceKind);
+            function inferFromIndexTypes(source: Type, target: Type) {
+                const targetStringIndexType = getIndexTypeOfType(target, IndexKind.String);
+                if (targetStringIndexType) {
+                    const sourceIndexType = getIndexTypeOfType(source, IndexKind.String) ||
+                        getImplicitIndexTypeOfType(source, IndexKind.String);
                     if (sourceIndexType) {
-                        inferFromTypes(sourceIndexType, targetIndexType);
+                        inferFromTypes(sourceIndexType, targetStringIndexType);
+                    }
+                }
+                const targetNumberIndexType = getIndexTypeOfType(target, IndexKind.Number);
+                if (targetNumberIndexType) {
+                    const sourceIndexType = getIndexTypeOfType(source, IndexKind.Number) ||
+                        getIndexTypeOfType(source, IndexKind.String) ||
+                        getImplicitIndexTypeOfType(source, IndexKind.Number);
+                    if (sourceIndexType) {
+                        inferFromTypes(sourceIndexType, targetNumberIndexType);
                     }
                 }
             }
@@ -7824,11 +7844,6 @@ namespace ts {
             return !!(type.flags & TypeFlags.Union ? forEach((<UnionType>type).types, isTupleLikeType) : isTupleLikeType(type));
         }
 
-        // Return true if the given contextual type provides an index signature of the given kind
-        function contextualTypeHasIndexSignature(type: Type, kind: IndexKind): boolean {
-            return !!(type.flags & TypeFlags.Union ? forEach((<UnionType>type).types, t => getIndexInfoOfStructuredType(t, kind)) : getIndexInfoOfStructuredType(type, kind));
-        }
-
         // In an object literal contextually typed by a type T, the contextual type of a property assignment is the type of
         // the matching property in T, if one exists. Otherwise, it is the type of the numeric index signature in T, if one
         // exists. Otherwise, it is the type of the string index signature in T, if one exists.
@@ -8224,6 +8239,17 @@ namespace ts {
             return links.resolvedType;
         }
 
+        function getObjectLiteralIndexInfo(node: ObjectLiteralExpression, properties: Symbol[], kind: IndexKind): IndexInfo {
+            const propTypes: Type[] = [];
+            for (let i = 0; i < properties.length; i++) {
+                if (kind === IndexKind.String || isNumericName(node.properties[i].name)) {
+                    propTypes.push(getTypeOfSymbol(properties[i]));
+                }
+            }
+            const unionType = propTypes.length ? getUnionType(propTypes) : undefinedType;
+            return createIndexInfo(unionType, /*isReadonly*/ false);
+        }
+
         function checkObjectLiteral(node: ObjectLiteralExpression, contextualMapper?: TypeMapper): Type {
             const inDestructuringPattern = isAssignmentTarget(node);
             // Grammar checking
@@ -8235,8 +8261,10 @@ namespace ts {
             const contextualTypeHasPattern = contextualType && contextualType.pattern &&
                 (contextualType.pattern.kind === SyntaxKind.ObjectBindingPattern || contextualType.pattern.kind === SyntaxKind.ObjectLiteralExpression);
             let typeFlags: TypeFlags = 0;
-
             let patternWithComputedProperties = false;
+            let hasComputedStringProperty = false;
+            let hasComputedNumberProperty = false;
+
             for (const memberDecl of node.properties) {
                 let member = memberDecl.symbol;
                 if (memberDecl.kind === SyntaxKind.PropertyAssignment ||
@@ -8300,7 +8328,15 @@ namespace ts {
                     checkAccessorDeclaration(<AccessorDeclaration>memberDecl);
                 }
 
-                if (!hasDynamicName(memberDecl)) {
+                if (hasDynamicName(memberDecl)) {
+                    if (isNumericName(memberDecl.name)) {
+                        hasComputedNumberProperty = true;
+                    }
+                    else {
+                        hasComputedStringProperty = true;
+                    }
+                }
+                else {
                     propertiesTable[member.name] = member;
                 }
                 propertiesArray.push(member);
@@ -8321,8 +8357,8 @@ namespace ts {
                 }
             }
 
-            const stringIndexInfo = getIndexInfo(IndexKind.String);
-            const numberIndexInfo = getIndexInfo(IndexKind.Number);
+            const stringIndexInfo = hasComputedStringProperty ? getObjectLiteralIndexInfo(node, propertiesArray, IndexKind.String) : undefined;
+            const numberIndexInfo = hasComputedNumberProperty ? getObjectLiteralIndexInfo(node, propertiesArray, IndexKind.Number) : undefined;
             const result = createAnonymousType(node.symbol, propertiesTable, emptyArray, emptyArray, stringIndexInfo, numberIndexInfo);
             const freshObjectLiteralFlag = compilerOptions.suppressExcessPropertyErrors ? 0 : TypeFlags.FreshObjectLiteral;
             result.flags |= TypeFlags.ObjectLiteral | TypeFlags.ContainsObjectLiteral | freshObjectLiteralFlag | (typeFlags & TypeFlags.PropagatingFlags) | (patternWithComputedProperties ? TypeFlags.ObjectLiteralPatternWithComputedProperties : 0);
@@ -8330,29 +8366,6 @@ namespace ts {
                 result.pattern = node;
             }
             return result;
-
-            function getIndexInfo(kind: IndexKind) {
-                if (contextualType && contextualTypeHasIndexSignature(contextualType, kind)) {
-                    const propTypes: Type[] = [];
-                    for (let i = 0; i < propertiesArray.length; i++) {
-                        const propertyDecl = node.properties[i];
-                        if (kind === IndexKind.String || isNumericName(propertyDecl.name)) {
-                            // Do not call getSymbolOfNode(propertyDecl), as that will get the
-                            // original symbol for the node. We actually want to get the symbol
-                            // created by checkObjectLiteral, since that will be appropriately
-                            // contextually typed and resolved.
-                            const type = getTypeOfSymbol(propertiesArray[i]);
-                            if (!contains(propTypes, type)) {
-                                propTypes.push(type);
-                            }
-                        }
-                    }
-                    const unionType = propTypes.length ? getUnionType(propTypes) : undefinedType;
-                    typeFlags |= unionType.flags;
-                    return createIndexInfo(unionType, /*isReadonly*/ false);
-                }
-                return undefined;
-            }
         }
 
         function checkJsxSelfClosingElement(node: JsxSelfClosingElement) {
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index 5b93f61bb9042..2458e68f23c5c 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -1699,6 +1699,10 @@
         "category": "Error",
         "code": 2529
     },
+    "Property '{0}' is incompatible with index signature.": {
+        "category": "Error",
+        "code": 2530
+    },
     "JSX element attributes type '{0}' may not be a union type.": {
         "category": "Error",
         "code": 2600
diff --git a/tests/baselines/reference/augmentedTypeAssignmentCompatIndexSignature.errors.txt b/tests/baselines/reference/augmentedTypeAssignmentCompatIndexSignature.errors.txt
index eb5020e97f97e..e99cac7968cf8 100644
--- a/tests/baselines/reference/augmentedTypeAssignmentCompatIndexSignature.errors.txt
+++ b/tests/baselines/reference/augmentedTypeAssignmentCompatIndexSignature.errors.txt
@@ -1,10 +1,8 @@
-tests/cases/conformance/types/members/augmentedTypeAssignmentCompatIndexSignature.ts(15,5): error TS2322: Type '{}' is not assignable to type '{ [n: number]: Foo; }'.
-  Index signature is missing in type '{}'.
 tests/cases/conformance/types/members/augmentedTypeAssignmentCompatIndexSignature.ts(19,5): error TS2322: Type '() => void' is not assignable to type '{ [n: number]: Bar; }'.
   Index signature is missing in type '() => void'.
 
 
-==== tests/cases/conformance/types/members/augmentedTypeAssignmentCompatIndexSignature.ts (2 errors) ====
+==== tests/cases/conformance/types/members/augmentedTypeAssignmentCompatIndexSignature.ts (1 errors) ====
     interface Foo { a }
     interface Bar { b }
     
@@ -20,9 +18,6 @@ tests/cases/conformance/types/members/augmentedTypeAssignmentCompatIndexSignatur
     var f = () => { };
     
     var v1: {
-        ~~
-!!! error TS2322: Type '{}' is not assignable to type '{ [n: number]: Foo; }'.
-!!! error TS2322:   Index signature is missing in type '{}'.
         [n: number]: Foo
     } = o; // Should be allowed
     
diff --git a/tests/baselines/reference/badOverloadError.types b/tests/baselines/reference/badOverloadError.types
index b8ae583a73cb8..198582af2db9e 100644
--- a/tests/baselines/reference/badOverloadError.types
+++ b/tests/baselines/reference/badOverloadError.types
@@ -6,6 +6,6 @@ function method() {
 >dictionary : { [index: string]: string; }
 ><{ [index: string]: string; }>{} : { [index: string]: string; }
 >index : string
->{} : { [x: string]: undefined; }
+>{} : {}
 }
 
diff --git a/tests/baselines/reference/bestCommonTypeWithContextualTyping.types b/tests/baselines/reference/bestCommonTypeWithContextualTyping.types
index 628fe82012a8e..5baca43b75252 100644
--- a/tests/baselines/reference/bestCommonTypeWithContextualTyping.types
+++ b/tests/baselines/reference/bestCommonTypeWithContextualTyping.types
@@ -36,7 +36,7 @@ var obj: { [s: string]: Contextual } = { s: e }; // { s: Ellement; [s: string]:
 >obj : { [s: string]: Contextual; }
 >s : string
 >Contextual : Contextual
->{ s: e } : { [x: string]: Ellement; s: Ellement; }
+>{ s: e } : { s: Ellement; }
 >s : Ellement
 >e : Ellement
 
diff --git a/tests/baselines/reference/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.errors.txt b/tests/baselines/reference/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.errors.txt
index fe608b143799c..2efaf2e5ae2f7 100644
--- a/tests/baselines/reference/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.errors.txt
+++ b/tests/baselines/reference/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.errors.txt
@@ -1,70 +1,54 @@
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(26,12): error TS2365: Operator '<' cannot be applied to types '{ [a: string]: string; }' and '{ [b: string]: number; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(27,12): error TS2365: Operator '<' cannot be applied to types '{ [index: string]: Base; }' and '{ [index: string]: C; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(28,12): error TS2365: Operator '<' cannot be applied to types '{ [index: number]: Base; }' and '{ [index: number]: C; }'.
-tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(29,12): error TS2365: Operator '<' cannot be applied to types '{ [index: number]: Derived; }' and '{ [index: string]: Base; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(31,12): error TS2365: Operator '<' cannot be applied to types '{ [b: string]: number; }' and '{ [a: string]: string; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(32,12): error TS2365: Operator '<' cannot be applied to types '{ [index: string]: C; }' and '{ [index: string]: Base; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(33,12): error TS2365: Operator '<' cannot be applied to types '{ [index: number]: C; }' and '{ [index: number]: Base; }'.
-tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(34,12): error TS2365: Operator '<' cannot be applied to types '{ [index: string]: Base; }' and '{ [index: number]: Derived; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(37,12): error TS2365: Operator '>' cannot be applied to types '{ [a: string]: string; }' and '{ [b: string]: number; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(38,12): error TS2365: Operator '>' cannot be applied to types '{ [index: string]: Base; }' and '{ [index: string]: C; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(39,12): error TS2365: Operator '>' cannot be applied to types '{ [index: number]: Base; }' and '{ [index: number]: C; }'.
-tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(40,12): error TS2365: Operator '>' cannot be applied to types '{ [index: number]: Derived; }' and '{ [index: string]: Base; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(42,12): error TS2365: Operator '>' cannot be applied to types '{ [b: string]: number; }' and '{ [a: string]: string; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(43,12): error TS2365: Operator '>' cannot be applied to types '{ [index: string]: C; }' and '{ [index: string]: Base; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(44,12): error TS2365: Operator '>' cannot be applied to types '{ [index: number]: C; }' and '{ [index: number]: Base; }'.
-tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(45,12): error TS2365: Operator '>' cannot be applied to types '{ [index: string]: Base; }' and '{ [index: number]: Derived; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(48,12): error TS2365: Operator '<=' cannot be applied to types '{ [a: string]: string; }' and '{ [b: string]: number; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(49,12): error TS2365: Operator '<=' cannot be applied to types '{ [index: string]: Base; }' and '{ [index: string]: C; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(50,12): error TS2365: Operator '<=' cannot be applied to types '{ [index: number]: Base; }' and '{ [index: number]: C; }'.
-tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(51,12): error TS2365: Operator '<=' cannot be applied to types '{ [index: number]: Derived; }' and '{ [index: string]: Base; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(53,12): error TS2365: Operator '<=' cannot be applied to types '{ [b: string]: number; }' and '{ [a: string]: string; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(54,12): error TS2365: Operator '<=' cannot be applied to types '{ [index: string]: C; }' and '{ [index: string]: Base; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(55,12): error TS2365: Operator '<=' cannot be applied to types '{ [index: number]: C; }' and '{ [index: number]: Base; }'.
-tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(56,12): error TS2365: Operator '<=' cannot be applied to types '{ [index: string]: Base; }' and '{ [index: number]: Derived; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(59,12): error TS2365: Operator '>=' cannot be applied to types '{ [a: string]: string; }' and '{ [b: string]: number; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(60,12): error TS2365: Operator '>=' cannot be applied to types '{ [index: string]: Base; }' and '{ [index: string]: C; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(61,12): error TS2365: Operator '>=' cannot be applied to types '{ [index: number]: Base; }' and '{ [index: number]: C; }'.
-tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(62,12): error TS2365: Operator '>=' cannot be applied to types '{ [index: number]: Derived; }' and '{ [index: string]: Base; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(64,12): error TS2365: Operator '>=' cannot be applied to types '{ [b: string]: number; }' and '{ [a: string]: string; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(65,12): error TS2365: Operator '>=' cannot be applied to types '{ [index: string]: C; }' and '{ [index: string]: Base; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(66,12): error TS2365: Operator '>=' cannot be applied to types '{ [index: number]: C; }' and '{ [index: number]: Base; }'.
-tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(67,12): error TS2365: Operator '>=' cannot be applied to types '{ [index: string]: Base; }' and '{ [index: number]: Derived; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(70,12): error TS2365: Operator '==' cannot be applied to types '{ [a: string]: string; }' and '{ [b: string]: number; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(71,12): error TS2365: Operator '==' cannot be applied to types '{ [index: string]: Base; }' and '{ [index: string]: C; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(72,12): error TS2365: Operator '==' cannot be applied to types '{ [index: number]: Base; }' and '{ [index: number]: C; }'.
-tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(73,12): error TS2365: Operator '==' cannot be applied to types '{ [index: number]: Derived; }' and '{ [index: string]: Base; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(75,12): error TS2365: Operator '==' cannot be applied to types '{ [b: string]: number; }' and '{ [a: string]: string; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(76,12): error TS2365: Operator '==' cannot be applied to types '{ [index: string]: C; }' and '{ [index: string]: Base; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(77,12): error TS2365: Operator '==' cannot be applied to types '{ [index: number]: C; }' and '{ [index: number]: Base; }'.
-tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(78,12): error TS2365: Operator '==' cannot be applied to types '{ [index: string]: Base; }' and '{ [index: number]: Derived; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(81,12): error TS2365: Operator '!=' cannot be applied to types '{ [a: string]: string; }' and '{ [b: string]: number; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(82,12): error TS2365: Operator '!=' cannot be applied to types '{ [index: string]: Base; }' and '{ [index: string]: C; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(83,12): error TS2365: Operator '!=' cannot be applied to types '{ [index: number]: Base; }' and '{ [index: number]: C; }'.
-tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(84,12): error TS2365: Operator '!=' cannot be applied to types '{ [index: number]: Derived; }' and '{ [index: string]: Base; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(86,12): error TS2365: Operator '!=' cannot be applied to types '{ [b: string]: number; }' and '{ [a: string]: string; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(87,12): error TS2365: Operator '!=' cannot be applied to types '{ [index: string]: C; }' and '{ [index: string]: Base; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(88,12): error TS2365: Operator '!=' cannot be applied to types '{ [index: number]: C; }' and '{ [index: number]: Base; }'.
-tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(89,12): error TS2365: Operator '!=' cannot be applied to types '{ [index: string]: Base; }' and '{ [index: number]: Derived; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(92,12): error TS2365: Operator '===' cannot be applied to types '{ [a: string]: string; }' and '{ [b: string]: number; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(93,12): error TS2365: Operator '===' cannot be applied to types '{ [index: string]: Base; }' and '{ [index: string]: C; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(94,12): error TS2365: Operator '===' cannot be applied to types '{ [index: number]: Base; }' and '{ [index: number]: C; }'.
-tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(95,12): error TS2365: Operator '===' cannot be applied to types '{ [index: number]: Derived; }' and '{ [index: string]: Base; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(97,12): error TS2365: Operator '===' cannot be applied to types '{ [b: string]: number; }' and '{ [a: string]: string; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(98,12): error TS2365: Operator '===' cannot be applied to types '{ [index: string]: C; }' and '{ [index: string]: Base; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(99,12): error TS2365: Operator '===' cannot be applied to types '{ [index: number]: C; }' and '{ [index: number]: Base; }'.
-tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(100,12): error TS2365: Operator '===' cannot be applied to types '{ [index: string]: Base; }' and '{ [index: number]: Derived; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(103,12): error TS2365: Operator '!==' cannot be applied to types '{ [a: string]: string; }' and '{ [b: string]: number; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(104,12): error TS2365: Operator '!==' cannot be applied to types '{ [index: string]: Base; }' and '{ [index: string]: C; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(105,12): error TS2365: Operator '!==' cannot be applied to types '{ [index: number]: Base; }' and '{ [index: number]: C; }'.
-tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(106,12): error TS2365: Operator '!==' cannot be applied to types '{ [index: number]: Derived; }' and '{ [index: string]: Base; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(108,12): error TS2365: Operator '!==' cannot be applied to types '{ [b: string]: number; }' and '{ [a: string]: string; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(109,12): error TS2365: Operator '!==' cannot be applied to types '{ [index: string]: C; }' and '{ [index: string]: Base; }'.
 tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(110,12): error TS2365: Operator '!==' cannot be applied to types '{ [index: number]: C; }' and '{ [index: number]: Base; }'.
-tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts(111,12): error TS2365: Operator '!==' cannot be applied to types '{ [index: string]: Base; }' and '{ [index: number]: Derived; }'.
 
 
-==== tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts (64 errors) ====
+==== tests/cases/conformance/expressions/binaryOperators/comparisonOperator/comparisonOperatorWithNoRelationshipObjectsOnIndexSignature.ts (48 errors) ====
     class Base {
         public a: string;
     }
@@ -100,8 +84,6 @@ tests/cases/conformance/expressions/binaryOperators/comparisonOperator/compariso
                ~~~~~~~
 !!! error TS2365: Operator '<' cannot be applied to types '{ [index: number]: Base; }' and '{ [index: number]: C; }'.
     var r1a4 = a4 < b4;
-               ~~~~~~~
-!!! error TS2365: Operator '<' cannot be applied to types '{ [index: number]: Derived; }' and '{ [index: string]: Base; }'.
     
     var r1b1 = b1 < a1;
                ~~~~~~~
@@ -113,8 +95,6 @@ tests/cases/conformance/expressions/binaryOperators/comparisonOperator/compariso
                ~~~~~~~
 !!! error TS2365: Operator '<' cannot be applied to types '{ [index: number]: C; }' and '{ [index: number]: Base; }'.
     var r1b4 = b4 < a4;
-               ~~~~~~~
-!!! error TS2365: Operator '<' cannot be applied to types '{ [index: string]: Base; }' and '{ [index: number]: Derived; }'.
     
     // operator >
     var r2a1 = a1 > b1;
@@ -127,8 +107,6 @@ tests/cases/conformance/expressions/binaryOperators/comparisonOperator/compariso
                ~~~~~~~
 !!! error TS2365: Operator '>' cannot be applied to types '{ [index: number]: Base; }' and '{ [index: number]: C; }'.
     var r2a4 = a4 > b4;
-               ~~~~~~~
-!!! error TS2365: Operator '>' cannot be applied to types '{ [index: number]: Derived; }' and '{ [index: string]: Base; }'.
     
     var r2b1 = b1 > a1;
                ~~~~~~~
@@ -140,8 +118,6 @@ tests/cases/conformance/expressions/binaryOperators/comparisonOperator/compariso
                ~~~~~~~
 !!! error TS2365: Operator '>' cannot be applied to types '{ [index: number]: C; }' and '{ [index: number]: Base; }'.
     var r2b4 = b4 > a4;
-               ~~~~~~~
-!!! error TS2365: Operator '>' cannot be applied to types '{ [index: string]: Base; }' and '{ [index: number]: Derived; }'.
     
     // operator <=
     var r3a1 = a1 <= b1;
@@ -154,8 +130,6 @@ tests/cases/conformance/expressions/binaryOperators/comparisonOperator/compariso
                ~~~~~~~~
 !!! error TS2365: Operator '<=' cannot be applied to types '{ [index: number]: Base; }' and '{ [index: number]: C; }'.
     var r3a4 = a4 <= b4;
-               ~~~~~~~~
-!!! error TS2365: Operator '<=' cannot be applied to types '{ [index: number]: Derived; }' and '{ [index: string]: Base; }'.
     
     var r3b1 = b1 <= a1;
                ~~~~~~~~
@@ -167,8 +141,6 @@ tests/cases/conformance/expressions/binaryOperators/comparisonOperator/compariso
                ~~~~~~~~
 !!! error TS2365: Operator '<=' cannot be applied to types '{ [index: number]: C; }' and '{ [index: number]: Base; }'.
     var r3b4 = b4 <= a4;
-               ~~~~~~~~
-!!! error TS2365: Operator '<=' cannot be applied to types '{ [index: string]: Base; }' and '{ [index: number]: Derived; }'.
     
     // operator >=
     var r4a1 = a1 >= b1;
@@ -181,8 +153,6 @@ tests/cases/conformance/expressions/binaryOperators/comparisonOperator/compariso
                ~~~~~~~~
 !!! error TS2365: Operator '>=' cannot be applied to types '{ [index: number]: Base; }' and '{ [index: number]: C; }'.
     var r4a4 = a4 >= b4;
-               ~~~~~~~~
-!!! error TS2365: Operator '>=' cannot be applied to types '{ [index: number]: Derived; }' and '{ [index: string]: Base; }'.
     
     var r4b1 = b1 >= a1;
                ~~~~~~~~
@@ -194,8 +164,6 @@ tests/cases/conformance/expressions/binaryOperators/comparisonOperator/compariso
                ~~~~~~~~
 !!! error TS2365: Operator '>=' cannot be applied to types '{ [index: number]: C; }' and '{ [index: number]: Base; }'.
     var r4b4 = b4 >= a4;
-               ~~~~~~~~
-!!! error TS2365: Operator '>=' cannot be applied to types '{ [index: string]: Base; }' and '{ [index: number]: Derived; }'.
     
     // operator ==
     var r5a1 = a1 == b1;
@@ -208,8 +176,6 @@ tests/cases/conformance/expressions/binaryOperators/comparisonOperator/compariso
                ~~~~~~~~
 !!! error TS2365: Operator '==' cannot be applied to types '{ [index: number]: Base; }' and '{ [index: number]: C; }'.
     var r5a4 = a4 == b4;
-               ~~~~~~~~
-!!! error TS2365: Operator '==' cannot be applied to types '{ [index: number]: Derived; }' and '{ [index: string]: Base; }'.
     
     var r5b1 = b1 == a1;
                ~~~~~~~~
@@ -221,8 +187,6 @@ tests/cases/conformance/expressions/binaryOperators/comparisonOperator/compariso
                ~~~~~~~~
 !!! error TS2365: Operator '==' cannot be applied to types '{ [index: number]: C; }' and '{ [index: number]: Base; }'.
     var r5b4 = b4 == a4;
-               ~~~~~~~~
-!!! error TS2365: Operator '==' cannot be applied to types '{ [index: string]: Base; }' and '{ [index: number]: Derived; }'.
     
     // operator !=
     var r6a1 = a1 != b1;
@@ -235,8 +199,6 @@ tests/cases/conformance/expressions/binaryOperators/comparisonOperator/compariso
                ~~~~~~~~
 !!! error TS2365: Operator '!=' cannot be applied to types '{ [index: number]: Base; }' and '{ [index: number]: C; }'.
     var r6a4 = a4 != b4;
-               ~~~~~~~~
-!!! error TS2365: Operator '!=' cannot be applied to types '{ [index: number]: Derived; }' and '{ [index: string]: Base; }'.
     
     var r6b1 = b1 != a1;
                ~~~~~~~~
@@ -248,8 +210,6 @@ tests/cases/conformance/expressions/binaryOperators/comparisonOperator/compariso
                ~~~~~~~~
 !!! error TS2365: Operator '!=' cannot be applied to types '{ [index: number]: C; }' and '{ [index: number]: Base; }'.
     var r6b4 = b4 != a4;
-               ~~~~~~~~
-!!! error TS2365: Operator '!=' cannot be applied to types '{ [index: string]: Base; }' and '{ [index: number]: Derived; }'.
     
     // operator ===
     var r7a1 = a1 === b1;
@@ -262,8 +222,6 @@ tests/cases/conformance/expressions/binaryOperators/comparisonOperator/compariso
                ~~~~~~~~~
 !!! error TS2365: Operator '===' cannot be applied to types '{ [index: number]: Base; }' and '{ [index: number]: C; }'.
     var r7a4 = a4 === b4;
-               ~~~~~~~~~
-!!! error TS2365: Operator '===' cannot be applied to types '{ [index: number]: Derived; }' and '{ [index: string]: Base; }'.
     
     var r7b1 = b1 === a1;
                ~~~~~~~~~
@@ -275,8 +233,6 @@ tests/cases/conformance/expressions/binaryOperators/comparisonOperator/compariso
                ~~~~~~~~~
 !!! error TS2365: Operator '===' cannot be applied to types '{ [index: number]: C; }' and '{ [index: number]: Base; }'.
     var r7b4 = b4 === a4;
-               ~~~~~~~~~
-!!! error TS2365: Operator '===' cannot be applied to types '{ [index: string]: Base; }' and '{ [index: number]: Derived; }'.
     
     // operator !==
     var r8a1 = a1 !== b1;
@@ -289,8 +245,6 @@ tests/cases/conformance/expressions/binaryOperators/comparisonOperator/compariso
                ~~~~~~~~~
 !!! error TS2365: Operator '!==' cannot be applied to types '{ [index: number]: Base; }' and '{ [index: number]: C; }'.
     var r8a4 = a4 !== b4;
-               ~~~~~~~~~
-!!! error TS2365: Operator '!==' cannot be applied to types '{ [index: number]: Derived; }' and '{ [index: string]: Base; }'.
     
     var r8b1 = b1 !== a1;
                ~~~~~~~~~
@@ -301,6 +255,4 @@ tests/cases/conformance/expressions/binaryOperators/comparisonOperator/compariso
     var r8b3 = b3 !== a3;
                ~~~~~~~~~
 !!! error TS2365: Operator '!==' cannot be applied to types '{ [index: number]: C; }' and '{ [index: number]: Base; }'.
-    var r8b4 = b4 !== a4;
-               ~~~~~~~~~
-!!! error TS2365: Operator '!==' cannot be applied to types '{ [index: string]: Base; }' and '{ [index: number]: Derived; }'.
\ No newline at end of file
+    var r8b4 = b4 !== a4;
\ No newline at end of file
diff --git a/tests/baselines/reference/compoundAdditionAssignmentLHSCanBeAssigned.types b/tests/baselines/reference/compoundAdditionAssignmentLHSCanBeAssigned.types
index 92835611c6dcc..e40422450b44f 100644
--- a/tests/baselines/reference/compoundAdditionAssignmentLHSCanBeAssigned.types
+++ b/tests/baselines/reference/compoundAdditionAssignmentLHSCanBeAssigned.types
@@ -98,7 +98,7 @@ x2 += E.a;
 x2 += {};
 >x2 += {} : string
 >x2 : string
->{} : { [x: number]: undefined; }
+>{} : {}
 
 x2 += null;
 >x2 += null : string
diff --git a/tests/baselines/reference/computedPropertyNames10_ES5.types b/tests/baselines/reference/computedPropertyNames10_ES5.types
index 9dea9cfca9390..b9d999397abf1 100644
--- a/tests/baselines/reference/computedPropertyNames10_ES5.types
+++ b/tests/baselines/reference/computedPropertyNames10_ES5.types
@@ -9,8 +9,8 @@ var a: any;
 >a : any
 
 var v = {
->v : { [0](): void; [""](): void; }
->{    [s]() { },    [n]() { },    [s + s]() { },    [s + n]() { },    [+s]() { },    [""]() { },    [0]() { },    [a]() { },    [<any>true]() { },    [`hello bye`]() { },    [`hello ${a} bye`]() { }} : { [0](): void; [""](): void; }
+>v : { [x: string]: () => void; [x: number]: () => void; [0](): void; [""](): void; }
+>{    [s]() { },    [n]() { },    [s + s]() { },    [s + n]() { },    [+s]() { },    [""]() { },    [0]() { },    [a]() { },    [<any>true]() { },    [`hello bye`]() { },    [`hello ${a} bye`]() { }} : { [x: string]: () => void; [x: number]: () => void; [0](): void; [""](): void; }
 
     [s]() { },
 >s : string
diff --git a/tests/baselines/reference/computedPropertyNames10_ES6.types b/tests/baselines/reference/computedPropertyNames10_ES6.types
index d2faa13898076..1883febb39b79 100644
--- a/tests/baselines/reference/computedPropertyNames10_ES6.types
+++ b/tests/baselines/reference/computedPropertyNames10_ES6.types
@@ -9,8 +9,8 @@ var a: any;
 >a : any
 
 var v = {
->v : { [0](): void; [""](): void; }
->{    [s]() { },    [n]() { },    [s + s]() { },    [s + n]() { },    [+s]() { },    [""]() { },    [0]() { },    [a]() { },    [<any>true]() { },    [`hello bye`]() { },    [`hello ${a} bye`]() { }} : { [0](): void; [""](): void; }
+>v : { [x: string]: () => void; [x: number]: () => void; [0](): void; [""](): void; }
+>{    [s]() { },    [n]() { },    [s + s]() { },    [s + n]() { },    [+s]() { },    [""]() { },    [0]() { },    [a]() { },    [<any>true]() { },    [`hello bye`]() { },    [`hello ${a} bye`]() { }} : { [x: string]: () => void; [x: number]: () => void; [0](): void; [""](): void; }
 
     [s]() { },
 >s : string
diff --git a/tests/baselines/reference/computedPropertyNames11_ES5.types b/tests/baselines/reference/computedPropertyNames11_ES5.types
index ae626ec3cba28..e15b46cc6c174 100644
--- a/tests/baselines/reference/computedPropertyNames11_ES5.types
+++ b/tests/baselines/reference/computedPropertyNames11_ES5.types
@@ -9,8 +9,8 @@ var a: any;
 >a : any
 
 var v = {
->v : { readonly [0]: number; [""]: any; }
->{    get [s]() { return 0; },    set [n](v) { },    get [s + s]() { return 0; },    set [s + n](v) { },    get [+s]() { return 0; },    set [""](v) { },    get [0]() { return 0; },    set [a](v) { },    get [<any>true]() { return 0; },    set [`hello bye`](v) { },    get [`hello ${a} bye`]() { return 0; }} : { readonly [0]: number; [""]: any; }
+>v : { [x: string]: any; [x: number]: any; readonly [0]: number; [""]: any; }
+>{    get [s]() { return 0; },    set [n](v) { },    get [s + s]() { return 0; },    set [s + n](v) { },    get [+s]() { return 0; },    set [""](v) { },    get [0]() { return 0; },    set [a](v) { },    get [<any>true]() { return 0; },    set [`hello bye`](v) { },    get [`hello ${a} bye`]() { return 0; }} : { [x: string]: any; [x: number]: any; readonly [0]: number; [""]: any; }
 
     get [s]() { return 0; },
 >s : string
diff --git a/tests/baselines/reference/computedPropertyNames11_ES6.types b/tests/baselines/reference/computedPropertyNames11_ES6.types
index 06dc26e984305..eb5fc105a7a82 100644
--- a/tests/baselines/reference/computedPropertyNames11_ES6.types
+++ b/tests/baselines/reference/computedPropertyNames11_ES6.types
@@ -9,8 +9,8 @@ var a: any;
 >a : any
 
 var v = {
->v : { readonly [0]: number; [""]: any; }
->{    get [s]() { return 0; },    set [n](v) { },    get [s + s]() { return 0; },    set [s + n](v) { },    get [+s]() { return 0; },    set [""](v) { },    get [0]() { return 0; },    set [a](v) { },    get [<any>true]() { return 0; },    set [`hello bye`](v) { },    get [`hello ${a} bye`]() { return 0; }} : { readonly [0]: number; [""]: any; }
+>v : { [x: string]: any; [x: number]: any; readonly [0]: number; [""]: any; }
+>{    get [s]() { return 0; },    set [n](v) { },    get [s + s]() { return 0; },    set [s + n](v) { },    get [+s]() { return 0; },    set [""](v) { },    get [0]() { return 0; },    set [a](v) { },    get [<any>true]() { return 0; },    set [`hello bye`](v) { },    get [`hello ${a} bye`]() { return 0; }} : { [x: string]: any; [x: number]: any; readonly [0]: number; [""]: any; }
 
     get [s]() { return 0; },
 >s : string
diff --git a/tests/baselines/reference/computedPropertyNames18_ES5.types b/tests/baselines/reference/computedPropertyNames18_ES5.types
index c60ab32d3f884..d6808a8edc001 100644
--- a/tests/baselines/reference/computedPropertyNames18_ES5.types
+++ b/tests/baselines/reference/computedPropertyNames18_ES5.types
@@ -3,8 +3,8 @@ function foo() {
 >foo : () => void
 
     var obj = {
->obj : {}
->{        [this.bar]: 0    } : {}
+>obj : { [x: number]: number; }
+>{        [this.bar]: 0    } : { [x: number]: number; }
 
         [this.bar]: 0
 >this.bar : any
diff --git a/tests/baselines/reference/computedPropertyNames18_ES6.types b/tests/baselines/reference/computedPropertyNames18_ES6.types
index 33a15b6c5a9e4..11d58e48c6920 100644
--- a/tests/baselines/reference/computedPropertyNames18_ES6.types
+++ b/tests/baselines/reference/computedPropertyNames18_ES6.types
@@ -3,8 +3,8 @@ function foo() {
 >foo : () => void
 
     var obj = {
->obj : {}
->{        [this.bar]: 0    } : {}
+>obj : { [x: number]: number; }
+>{        [this.bar]: 0    } : { [x: number]: number; }
 
         [this.bar]: 0
 >this.bar : any
diff --git a/tests/baselines/reference/computedPropertyNames1_ES5.types b/tests/baselines/reference/computedPropertyNames1_ES5.types
index 6c94c846f30a4..bcff3b34177f7 100644
--- a/tests/baselines/reference/computedPropertyNames1_ES5.types
+++ b/tests/baselines/reference/computedPropertyNames1_ES5.types
@@ -1,7 +1,7 @@
 === tests/cases/conformance/es6/computedProperties/computedPropertyNames1_ES5.ts ===
 var v = {
->v : {}
->{    get [0 + 1]() { return 0 },    set [0 + 1](v: string) { } //No error} : {}
+>v : { [x: number]: number | string; }
+>{    get [0 + 1]() { return 0 },    set [0 + 1](v: string) { } //No error} : { [x: number]: number | string; }
 
     get [0 + 1]() { return 0 },
 >0 + 1 : number
diff --git a/tests/baselines/reference/computedPropertyNames1_ES6.types b/tests/baselines/reference/computedPropertyNames1_ES6.types
index 95e5a011ea229..df2237a463f02 100644
--- a/tests/baselines/reference/computedPropertyNames1_ES6.types
+++ b/tests/baselines/reference/computedPropertyNames1_ES6.types
@@ -1,7 +1,7 @@
 === tests/cases/conformance/es6/computedProperties/computedPropertyNames1_ES6.ts ===
 var v = {
->v : {}
->{    get [0 + 1]() { return 0 },    set [0 + 1](v: string) { } //No error} : {}
+>v : { [x: number]: number | string; }
+>{    get [0 + 1]() { return 0 },    set [0 + 1](v: string) { } //No error} : { [x: number]: number | string; }
 
     get [0 + 1]() { return 0 },
 >0 + 1 : number
diff --git a/tests/baselines/reference/computedPropertyNames20_ES5.types b/tests/baselines/reference/computedPropertyNames20_ES5.types
index 91cc2c42963aa..65ee55be379fc 100644
--- a/tests/baselines/reference/computedPropertyNames20_ES5.types
+++ b/tests/baselines/reference/computedPropertyNames20_ES5.types
@@ -1,7 +1,7 @@
 === tests/cases/conformance/es6/computedProperties/computedPropertyNames20_ES5.ts ===
 var obj = {
->obj : {}
->{    [this.bar]: 0} : {}
+>obj : { [x: number]: number; }
+>{    [this.bar]: 0} : { [x: number]: number; }
 
     [this.bar]: 0
 >this.bar : any
diff --git a/tests/baselines/reference/computedPropertyNames20_ES6.types b/tests/baselines/reference/computedPropertyNames20_ES6.types
index 4ef6f675cce6e..91e5c8d78433b 100644
--- a/tests/baselines/reference/computedPropertyNames20_ES6.types
+++ b/tests/baselines/reference/computedPropertyNames20_ES6.types
@@ -1,7 +1,7 @@
 === tests/cases/conformance/es6/computedProperties/computedPropertyNames20_ES6.ts ===
 var obj = {
->obj : {}
->{    [this.bar]: 0} : {}
+>obj : { [x: number]: number; }
+>{    [this.bar]: 0} : { [x: number]: number; }
 
     [this.bar]: 0
 >this.bar : any
diff --git a/tests/baselines/reference/computedPropertyNames22_ES5.types b/tests/baselines/reference/computedPropertyNames22_ES5.types
index ca59250825c1d..eeec22d2e6129 100644
--- a/tests/baselines/reference/computedPropertyNames22_ES5.types
+++ b/tests/baselines/reference/computedPropertyNames22_ES5.types
@@ -6,8 +6,8 @@ class C {
 >bar : () => number
 
         var obj = {
->obj : {}
->{            [this.bar()]() { }        } : {}
+>obj : { [x: number]: () => void; }
+>{            [this.bar()]() { }        } : { [x: number]: () => void; }
 
             [this.bar()]() { }
 >this.bar() : number
diff --git a/tests/baselines/reference/computedPropertyNames22_ES6.types b/tests/baselines/reference/computedPropertyNames22_ES6.types
index d5fbce29f7ddd..af9ef9d3a317f 100644
--- a/tests/baselines/reference/computedPropertyNames22_ES6.types
+++ b/tests/baselines/reference/computedPropertyNames22_ES6.types
@@ -6,8 +6,8 @@ class C {
 >bar : () => number
 
         var obj = {
->obj : {}
->{            [this.bar()]() { }        } : {}
+>obj : { [x: number]: () => void; }
+>{            [this.bar()]() { }        } : { [x: number]: () => void; }
 
             [this.bar()]() { }
 >this.bar() : number
diff --git a/tests/baselines/reference/computedPropertyNames25_ES5.types b/tests/baselines/reference/computedPropertyNames25_ES5.types
index 6ca67cce4107b..f1acc296709a5 100644
--- a/tests/baselines/reference/computedPropertyNames25_ES5.types
+++ b/tests/baselines/reference/computedPropertyNames25_ES5.types
@@ -17,8 +17,8 @@ class C extends Base {
 >foo : () => number
 
         var obj = {
->obj : {}
->{            [super.bar()]() { }        } : {}
+>obj : { [x: number]: () => void; }
+>{            [super.bar()]() { }        } : { [x: number]: () => void; }
 
             [super.bar()]() { }
 >super.bar() : number
diff --git a/tests/baselines/reference/computedPropertyNames25_ES6.types b/tests/baselines/reference/computedPropertyNames25_ES6.types
index 1c093ebc59f6f..26c3801390640 100644
--- a/tests/baselines/reference/computedPropertyNames25_ES6.types
+++ b/tests/baselines/reference/computedPropertyNames25_ES6.types
@@ -17,8 +17,8 @@ class C extends Base {
 >foo : () => number
 
         var obj = {
->obj : {}
->{            [super.bar()]() { }        } : {}
+>obj : { [x: number]: () => void; }
+>{            [super.bar()]() { }        } : { [x: number]: () => void; }
 
             [super.bar()]() { }
 >super.bar() : number
diff --git a/tests/baselines/reference/computedPropertyNames28_ES5.types b/tests/baselines/reference/computedPropertyNames28_ES5.types
index 273dcd426d82f..89a2a7ac017e6 100644
--- a/tests/baselines/reference/computedPropertyNames28_ES5.types
+++ b/tests/baselines/reference/computedPropertyNames28_ES5.types
@@ -12,8 +12,8 @@ class C extends Base {
 >super : typeof Base
 
         var obj = {
->obj : {}
->{            [(super(), "prop")]() { }        } : {}
+>obj : { [x: string]: () => void; }
+>{            [(super(), "prop")]() { }        } : { [x: string]: () => void; }
 
             [(super(), "prop")]() { }
 >(super(), "prop") : string
diff --git a/tests/baselines/reference/computedPropertyNames28_ES6.types b/tests/baselines/reference/computedPropertyNames28_ES6.types
index a34fb33f6c7d7..df020c9a5ff55 100644
--- a/tests/baselines/reference/computedPropertyNames28_ES6.types
+++ b/tests/baselines/reference/computedPropertyNames28_ES6.types
@@ -12,8 +12,8 @@ class C extends Base {
 >super : typeof Base
 
         var obj = {
->obj : {}
->{            [(super(), "prop")]() { }        } : {}
+>obj : { [x: string]: () => void; }
+>{            [(super(), "prop")]() { }        } : { [x: string]: () => void; }
 
             [(super(), "prop")]() { }
 >(super(), "prop") : string
diff --git a/tests/baselines/reference/computedPropertyNames29_ES5.types b/tests/baselines/reference/computedPropertyNames29_ES5.types
index f3448f10857bf..d2f89ef6b18e8 100644
--- a/tests/baselines/reference/computedPropertyNames29_ES5.types
+++ b/tests/baselines/reference/computedPropertyNames29_ES5.types
@@ -9,8 +9,8 @@ class C {
 >() => {            var obj = {                [this.bar()]() { } // needs capture            };        } : () => void
 
             var obj = {
->obj : {}
->{                [this.bar()]() { } // needs capture            } : {}
+>obj : { [x: number]: () => void; }
+>{                [this.bar()]() { } // needs capture            } : { [x: number]: () => void; }
 
                 [this.bar()]() { } // needs capture
 >this.bar() : number
diff --git a/tests/baselines/reference/computedPropertyNames29_ES6.types b/tests/baselines/reference/computedPropertyNames29_ES6.types
index cd01d37556a3c..bb324b2b38250 100644
--- a/tests/baselines/reference/computedPropertyNames29_ES6.types
+++ b/tests/baselines/reference/computedPropertyNames29_ES6.types
@@ -9,8 +9,8 @@ class C {
 >() => {            var obj = {                [this.bar()]() { } // needs capture            };        } : () => void
 
             var obj = {
->obj : {}
->{                [this.bar()]() { } // needs capture            } : {}
+>obj : { [x: number]: () => void; }
+>{                [this.bar()]() { } // needs capture            } : { [x: number]: () => void; }
 
                 [this.bar()]() { } // needs capture
 >this.bar() : number
diff --git a/tests/baselines/reference/computedPropertyNames31_ES5.types b/tests/baselines/reference/computedPropertyNames31_ES5.types
index 6c0f2572a0680..832b2bc067a62 100644
--- a/tests/baselines/reference/computedPropertyNames31_ES5.types
+++ b/tests/baselines/reference/computedPropertyNames31_ES5.types
@@ -20,8 +20,8 @@ class C extends Base {
 >() => {            var obj = {                [super.bar()]() { } // needs capture            };        } : () => void
 
             var obj = {
->obj : {}
->{                [super.bar()]() { } // needs capture            } : {}
+>obj : { [x: number]: () => void; }
+>{                [super.bar()]() { } // needs capture            } : { [x: number]: () => void; }
 
                 [super.bar()]() { } // needs capture
 >super.bar() : number
diff --git a/tests/baselines/reference/computedPropertyNames31_ES6.types b/tests/baselines/reference/computedPropertyNames31_ES6.types
index eaddc0368126f..4f59b1e8c6d34 100644
--- a/tests/baselines/reference/computedPropertyNames31_ES6.types
+++ b/tests/baselines/reference/computedPropertyNames31_ES6.types
@@ -20,8 +20,8 @@ class C extends Base {
 >() => {            var obj = {                [super.bar()]() { } // needs capture            };        } : () => void
 
             var obj = {
->obj : {}
->{                [super.bar()]() { } // needs capture            } : {}
+>obj : { [x: number]: () => void; }
+>{                [super.bar()]() { } // needs capture            } : { [x: number]: () => void; }
 
                 [super.bar()]() { } // needs capture
 >super.bar() : number
diff --git a/tests/baselines/reference/computedPropertyNames33_ES5.types b/tests/baselines/reference/computedPropertyNames33_ES5.types
index f44ac3ca7695d..7031981481f62 100644
--- a/tests/baselines/reference/computedPropertyNames33_ES5.types
+++ b/tests/baselines/reference/computedPropertyNames33_ES5.types
@@ -12,8 +12,8 @@ class C<T> {
 >bar : () => number
 
         var obj = {
->obj : {}
->{            [foo<T>()]() { }        } : {}
+>obj : { [x: string]: () => void; }
+>{            [foo<T>()]() { }        } : { [x: string]: () => void; }
 
             [foo<T>()]() { }
 >foo<T>() : string
diff --git a/tests/baselines/reference/computedPropertyNames33_ES6.types b/tests/baselines/reference/computedPropertyNames33_ES6.types
index 3081337c8bb3e..3c57daf2ace16 100644
--- a/tests/baselines/reference/computedPropertyNames33_ES6.types
+++ b/tests/baselines/reference/computedPropertyNames33_ES6.types
@@ -12,8 +12,8 @@ class C<T> {
 >bar : () => number
 
         var obj = {
->obj : {}
->{            [foo<T>()]() { }        } : {}
+>obj : { [x: string]: () => void; }
+>{            [foo<T>()]() { }        } : { [x: string]: () => void; }
 
             [foo<T>()]() { }
 >foo<T>() : string
diff --git a/tests/baselines/reference/computedPropertyNames46_ES5.types b/tests/baselines/reference/computedPropertyNames46_ES5.types
index 394b22bd9042c..b8df0d56e1398 100644
--- a/tests/baselines/reference/computedPropertyNames46_ES5.types
+++ b/tests/baselines/reference/computedPropertyNames46_ES5.types
@@ -1,7 +1,7 @@
 === tests/cases/conformance/es6/computedProperties/computedPropertyNames46_ES5.ts ===
 var o = {
->o : {}
->{    ["" || 0]: 0} : {}
+>o : { [x: string]: number; }
+>{    ["" || 0]: 0} : { [x: string]: number; }
 
     ["" || 0]: 0
 >"" || 0 : string | number
diff --git a/tests/baselines/reference/computedPropertyNames46_ES6.types b/tests/baselines/reference/computedPropertyNames46_ES6.types
index 864fd81321d29..a786eca200c35 100644
--- a/tests/baselines/reference/computedPropertyNames46_ES6.types
+++ b/tests/baselines/reference/computedPropertyNames46_ES6.types
@@ -1,7 +1,7 @@
 === tests/cases/conformance/es6/computedProperties/computedPropertyNames46_ES6.ts ===
 var o = {
->o : {}
->{    ["" || 0]: 0} : {}
+>o : { [x: string]: number; }
+>{    ["" || 0]: 0} : { [x: string]: number; }
 
     ["" || 0]: 0
 >"" || 0 : string | number
diff --git a/tests/baselines/reference/computedPropertyNames47_ES5.types b/tests/baselines/reference/computedPropertyNames47_ES5.types
index 6aa841ffd62eb..cdc2c3301f66b 100644
--- a/tests/baselines/reference/computedPropertyNames47_ES5.types
+++ b/tests/baselines/reference/computedPropertyNames47_ES5.types
@@ -8,8 +8,8 @@ enum E2 { x }
 >x : E2
 
 var o = {
->o : {}
->{    [E1.x || E2.x]: 0} : {}
+>o : { [x: number]: number; }
+>{    [E1.x || E2.x]: 0} : { [x: number]: number; }
 
     [E1.x || E2.x]: 0
 >E1.x || E2.x : E1 | E2
diff --git a/tests/baselines/reference/computedPropertyNames47_ES6.types b/tests/baselines/reference/computedPropertyNames47_ES6.types
index f038b172ca173..a923e934d66d7 100644
--- a/tests/baselines/reference/computedPropertyNames47_ES6.types
+++ b/tests/baselines/reference/computedPropertyNames47_ES6.types
@@ -8,8 +8,8 @@ enum E2 { x }
 >x : E2
 
 var o = {
->o : {}
->{    [E1.x || E2.x]: 0} : {}
+>o : { [x: number]: number; }
+>{    [E1.x || E2.x]: 0} : { [x: number]: number; }
 
     [E1.x || E2.x]: 0
 >E1.x || E2.x : E1 | E2
diff --git a/tests/baselines/reference/computedPropertyNames48_ES5.types b/tests/baselines/reference/computedPropertyNames48_ES5.types
index 2b9131a11c8b0..12752d8abeb15 100644
--- a/tests/baselines/reference/computedPropertyNames48_ES5.types
+++ b/tests/baselines/reference/computedPropertyNames48_ES5.types
@@ -39,9 +39,9 @@ extractIndexer({
 }); // Should return string
 
 extractIndexer({
->extractIndexer({    ["" || 0]: ""}) : any
+>extractIndexer({    ["" || 0]: ""}) : string
 >extractIndexer : <T>(p: { [n: number]: T; }) => T
->{    ["" || 0]: ""} : { [x: number]: undefined; }
+>{    ["" || 0]: ""} : { [x: string]: string; }
 
     ["" || 0]: ""
 >"" || 0 : string | number
diff --git a/tests/baselines/reference/computedPropertyNames48_ES6.types b/tests/baselines/reference/computedPropertyNames48_ES6.types
index 2b803b19bd69b..832bc3c702557 100644
--- a/tests/baselines/reference/computedPropertyNames48_ES6.types
+++ b/tests/baselines/reference/computedPropertyNames48_ES6.types
@@ -39,9 +39,9 @@ extractIndexer({
 }); // Should return string
 
 extractIndexer({
->extractIndexer({    ["" || 0]: ""}) : any
+>extractIndexer({    ["" || 0]: ""}) : string
 >extractIndexer : <T>(p: { [n: number]: T; }) => T
->{    ["" || 0]: ""} : { [x: number]: undefined; }
+>{    ["" || 0]: ""} : { [x: string]: string; }
 
     ["" || 0]: ""
 >"" || 0 : string | number
diff --git a/tests/baselines/reference/computedPropertyNames4_ES5.types b/tests/baselines/reference/computedPropertyNames4_ES5.types
index 6984d2e69b8a4..3c5f884640fbe 100644
--- a/tests/baselines/reference/computedPropertyNames4_ES5.types
+++ b/tests/baselines/reference/computedPropertyNames4_ES5.types
@@ -9,8 +9,8 @@ var a: any;
 >a : any
 
 var v = {
->v : { [0]: number; [""]: number; }
->{    [s]: 0,    [n]: n,    [s + s]: 1,    [s + n]: 2,    [+s]: s,    [""]: 0,    [0]: 0,    [a]: 1,    [<any>true]: 0,    [`hello bye`]: 0,    [`hello ${a} bye`]: 0} : { [0]: number; [""]: number; }
+>v : { [x: string]: number | string; [x: number]: number | string; [0]: number; [""]: number; }
+>{    [s]: 0,    [n]: n,    [s + s]: 1,    [s + n]: 2,    [+s]: s,    [""]: 0,    [0]: 0,    [a]: 1,    [<any>true]: 0,    [`hello bye`]: 0,    [`hello ${a} bye`]: 0} : { [x: string]: number | string; [x: number]: number | string; [0]: number; [""]: number; }
 
     [s]: 0,
 >s : string
diff --git a/tests/baselines/reference/computedPropertyNames4_ES6.types b/tests/baselines/reference/computedPropertyNames4_ES6.types
index 1fece561f5ae8..335c2415bd060 100644
--- a/tests/baselines/reference/computedPropertyNames4_ES6.types
+++ b/tests/baselines/reference/computedPropertyNames4_ES6.types
@@ -9,8 +9,8 @@ var a: any;
 >a : any
 
 var v = {
->v : { [0]: number; [""]: number; }
->{    [s]: 0,    [n]: n,    [s + s]: 1,    [s + n]: 2,    [+s]: s,    [""]: 0,    [0]: 0,    [a]: 1,    [<any>true]: 0,    [`hello bye`]: 0,    [`hello ${a} bye`]: 0} : { [0]: number; [""]: number; }
+>v : { [x: string]: number | string; [x: number]: number | string; [0]: number; [""]: number; }
+>{    [s]: 0,    [n]: n,    [s + s]: 1,    [s + n]: 2,    [+s]: s,    [""]: 0,    [0]: 0,    [a]: 1,    [<any>true]: 0,    [`hello bye`]: 0,    [`hello ${a} bye`]: 0} : { [x: string]: number | string; [x: number]: number | string; [0]: number; [""]: number; }
 
     [s]: 0,
 >s : string
diff --git a/tests/baselines/reference/computedPropertyNames7_ES5.types b/tests/baselines/reference/computedPropertyNames7_ES5.types
index 8ebd4d75668b6..3411198b59070 100644
--- a/tests/baselines/reference/computedPropertyNames7_ES5.types
+++ b/tests/baselines/reference/computedPropertyNames7_ES5.types
@@ -6,8 +6,8 @@ enum E {
 >member : E
 }
 var v = {
->v : {}
->{    [E.member]: 0} : {}
+>v : { [x: number]: number; }
+>{    [E.member]: 0} : { [x: number]: number; }
 
     [E.member]: 0
 >E.member : E
diff --git a/tests/baselines/reference/computedPropertyNames7_ES6.types b/tests/baselines/reference/computedPropertyNames7_ES6.types
index 3a78b9c0ec6cd..eb72d546dbcd5 100644
--- a/tests/baselines/reference/computedPropertyNames7_ES6.types
+++ b/tests/baselines/reference/computedPropertyNames7_ES6.types
@@ -6,8 +6,8 @@ enum E {
 >member : E
 }
 var v = {
->v : {}
->{    [E.member]: 0} : {}
+>v : { [x: number]: number; }
+>{    [E.member]: 0} : { [x: number]: number; }
 
     [E.member]: 0
 >E.member : E
diff --git a/tests/baselines/reference/computedPropertyNamesContextualType1_ES5.types b/tests/baselines/reference/computedPropertyNamesContextualType1_ES5.types
index bea7267d7d12d..09cad59462448 100644
--- a/tests/baselines/reference/computedPropertyNamesContextualType1_ES5.types
+++ b/tests/baselines/reference/computedPropertyNamesContextualType1_ES5.types
@@ -14,7 +14,7 @@ interface I {
 var o: I = {
 >o : I
 >I : I
->{    ["" + 0](y) { return y.length; },    ["" + 1]: y => y.length} : { [x: string]: (y: string) => number; [x: number]: undefined; }
+>{    ["" + 0](y) { return y.length; },    ["" + 1]: y => y.length} : { [x: string]: (y: string) => number; }
 
     ["" + 0](y) { return y.length; },
 >"" + 0 : string
diff --git a/tests/baselines/reference/computedPropertyNamesContextualType1_ES6.types b/tests/baselines/reference/computedPropertyNamesContextualType1_ES6.types
index c8d0be6e833d2..d9e9970ebec6a 100644
--- a/tests/baselines/reference/computedPropertyNamesContextualType1_ES6.types
+++ b/tests/baselines/reference/computedPropertyNamesContextualType1_ES6.types
@@ -14,7 +14,7 @@ interface I {
 var o: I = {
 >o : I
 >I : I
->{    ["" + 0](y) { return y.length; },    ["" + 1]: y => y.length} : { [x: string]: (y: string) => number; [x: number]: undefined; }
+>{    ["" + 0](y) { return y.length; },    ["" + 1]: y => y.length} : { [x: string]: (y: string) => number; }
 
     ["" + 0](y) { return y.length; },
 >"" + 0 : string
diff --git a/tests/baselines/reference/computedPropertyNamesContextualType2_ES5.types b/tests/baselines/reference/computedPropertyNamesContextualType2_ES5.types
index 52de216b803b1..5a5c48f253662 100644
--- a/tests/baselines/reference/computedPropertyNamesContextualType2_ES5.types
+++ b/tests/baselines/reference/computedPropertyNamesContextualType2_ES5.types
@@ -14,7 +14,7 @@ interface I {
 var o: I = {
 >o : I
 >I : I
->{    [+"foo"](y) { return y.length; },    [+"bar"]: y => y.length} : { [x: string]: (y: string) => number; [x: number]: (y: string) => number; }
+>{    [+"foo"](y) { return y.length; },    [+"bar"]: y => y.length} : { [x: number]: (y: string) => number; }
 
     [+"foo"](y) { return y.length; },
 >+"foo" : number
diff --git a/tests/baselines/reference/computedPropertyNamesContextualType2_ES6.types b/tests/baselines/reference/computedPropertyNamesContextualType2_ES6.types
index cbbe0edc6a177..330351790ca04 100644
--- a/tests/baselines/reference/computedPropertyNamesContextualType2_ES6.types
+++ b/tests/baselines/reference/computedPropertyNamesContextualType2_ES6.types
@@ -14,7 +14,7 @@ interface I {
 var o: I = {
 >o : I
 >I : I
->{    [+"foo"](y) { return y.length; },    [+"bar"]: y => y.length} : { [x: string]: (y: string) => number; [x: number]: (y: string) => number; }
+>{    [+"foo"](y) { return y.length; },    [+"bar"]: y => y.length} : { [x: number]: (y: string) => number; }
 
     [+"foo"](y) { return y.length; },
 >+"foo" : number
diff --git a/tests/baselines/reference/computedPropertyNamesContextualType3_ES5.types b/tests/baselines/reference/computedPropertyNamesContextualType3_ES5.types
index 5f647fb4c1b70..faff27c9154ba 100644
--- a/tests/baselines/reference/computedPropertyNamesContextualType3_ES5.types
+++ b/tests/baselines/reference/computedPropertyNamesContextualType3_ES5.types
@@ -10,7 +10,7 @@ interface I {
 var o: I = {
 >o : I
 >I : I
->{    [+"foo"](y) { return y.length; },    [+"bar"]: y => y.length} : { [x: string]: (y: string) => number; }
+>{    [+"foo"](y) { return y.length; },    [+"bar"]: y => y.length} : { [x: number]: (y: string) => number; }
 
     [+"foo"](y) { return y.length; },
 >+"foo" : number
diff --git a/tests/baselines/reference/computedPropertyNamesContextualType3_ES6.types b/tests/baselines/reference/computedPropertyNamesContextualType3_ES6.types
index e872df6f1b21c..18c3295794485 100644
--- a/tests/baselines/reference/computedPropertyNamesContextualType3_ES6.types
+++ b/tests/baselines/reference/computedPropertyNamesContextualType3_ES6.types
@@ -10,7 +10,7 @@ interface I {
 var o: I = {
 >o : I
 >I : I
->{    [+"foo"](y) { return y.length; },    [+"bar"]: y => y.length} : { [x: string]: (y: string) => number; }
+>{    [+"foo"](y) { return y.length; },    [+"bar"]: y => y.length} : { [x: number]: (y: string) => number; }
 
     [+"foo"](y) { return y.length; },
 >+"foo" : number
diff --git a/tests/baselines/reference/computedPropertyNamesContextualType4_ES5.types b/tests/baselines/reference/computedPropertyNamesContextualType4_ES5.types
index e5a57363ca060..6f75f1a363338 100644
--- a/tests/baselines/reference/computedPropertyNamesContextualType4_ES5.types
+++ b/tests/baselines/reference/computedPropertyNamesContextualType4_ES5.types
@@ -12,7 +12,7 @@ interface I {
 var o: I = {
 >o : I
 >I : I
->{    [""+"foo"]: "",    [""+"bar"]: 0} : { [x: string]: string | number; [x: number]: undefined; }
+>{    [""+"foo"]: "",    [""+"bar"]: 0} : { [x: string]: string | number; }
 
     [""+"foo"]: "",
 >""+"foo" : string
diff --git a/tests/baselines/reference/computedPropertyNamesContextualType4_ES6.types b/tests/baselines/reference/computedPropertyNamesContextualType4_ES6.types
index bdfa569752bab..9ee84176237af 100644
--- a/tests/baselines/reference/computedPropertyNamesContextualType4_ES6.types
+++ b/tests/baselines/reference/computedPropertyNamesContextualType4_ES6.types
@@ -12,7 +12,7 @@ interface I {
 var o: I = {
 >o : I
 >I : I
->{    [""+"foo"]: "",    [""+"bar"]: 0} : { [x: string]: string | number; [x: number]: undefined; }
+>{    [""+"foo"]: "",    [""+"bar"]: 0} : { [x: string]: string | number; }
 
     [""+"foo"]: "",
 >""+"foo" : string
diff --git a/tests/baselines/reference/computedPropertyNamesContextualType5_ES5.types b/tests/baselines/reference/computedPropertyNamesContextualType5_ES5.types
index e142fe937b998..38594f756ab61 100644
--- a/tests/baselines/reference/computedPropertyNamesContextualType5_ES5.types
+++ b/tests/baselines/reference/computedPropertyNamesContextualType5_ES5.types
@@ -12,7 +12,7 @@ interface I {
 var o: I = {
 >o : I
 >I : I
->{    [+"foo"]: "",    [+"bar"]: 0} : { [x: string]: string | number; [x: number]: string | number; }
+>{    [+"foo"]: "",    [+"bar"]: 0} : { [x: number]: string | number; }
 
     [+"foo"]: "",
 >+"foo" : number
diff --git a/tests/baselines/reference/computedPropertyNamesContextualType5_ES6.types b/tests/baselines/reference/computedPropertyNamesContextualType5_ES6.types
index 7b385b36770ec..a07b2e8cd95c1 100644
--- a/tests/baselines/reference/computedPropertyNamesContextualType5_ES6.types
+++ b/tests/baselines/reference/computedPropertyNamesContextualType5_ES6.types
@@ -12,7 +12,7 @@ interface I {
 var o: I = {
 >o : I
 >I : I
->{    [+"foo"]: "",    [+"bar"]: 0} : { [x: string]: string | number; [x: number]: string | number; }
+>{    [+"foo"]: "",    [+"bar"]: 0} : { [x: number]: string | number; }
 
     [+"foo"]: "",
 >+"foo" : number
diff --git a/tests/baselines/reference/computedPropertyNamesContextualType6_ES5.types b/tests/baselines/reference/computedPropertyNamesContextualType6_ES5.types
index a3a393fba0cbd..b49724ccded92 100644
--- a/tests/baselines/reference/computedPropertyNamesContextualType6_ES5.types
+++ b/tests/baselines/reference/computedPropertyNamesContextualType6_ES5.types
@@ -19,7 +19,7 @@ declare function foo<T>(obj: I<T>): T
 foo({
 >foo({    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]}) : string | (() => void) | boolean | number | number[]
 >foo : <T>(obj: I<T>) => T
->{    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]} : { [x: string]: string | (() => void) | boolean | number | number[]; 0: () => void; p: string; }
+>{    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]} : { [x: string]: string | (() => void) | boolean | number | number[]; [x: number]: (() => void) | number | number[]; 0: () => void; p: string; }
 
     p: "",
 >p : string
diff --git a/tests/baselines/reference/computedPropertyNamesContextualType6_ES6.types b/tests/baselines/reference/computedPropertyNamesContextualType6_ES6.types
index 4abefe4484331..e88959d7cdc5f 100644
--- a/tests/baselines/reference/computedPropertyNamesContextualType6_ES6.types
+++ b/tests/baselines/reference/computedPropertyNamesContextualType6_ES6.types
@@ -19,7 +19,7 @@ declare function foo<T>(obj: I<T>): T
 foo({
 >foo({    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]}) : string | (() => void) | boolean | number | number[]
 >foo : <T>(obj: I<T>) => T
->{    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]} : { [x: string]: string | (() => void) | boolean | number | number[]; 0: () => void; p: string; }
+>{    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]} : { [x: string]: string | (() => void) | boolean | number | number[]; [x: number]: (() => void) | number | number[]; 0: () => void; p: string; }
 
     p: "",
 >p : string
diff --git a/tests/baselines/reference/computedPropertyNamesContextualType7_ES5.types b/tests/baselines/reference/computedPropertyNamesContextualType7_ES5.types
index ae1004c9819e6..083388ba975a1 100644
--- a/tests/baselines/reference/computedPropertyNamesContextualType7_ES5.types
+++ b/tests/baselines/reference/computedPropertyNamesContextualType7_ES5.types
@@ -19,7 +19,7 @@ declare function foo<T>(obj: I<T>): T
 foo({
 >foo({    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]}) : (() => void) | number | number[]
 >foo : <T>(obj: I<T>) => T
->{    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]} : { [x: number]: (() => void) | number | number[]; 0: () => void; p: string; }
+>{    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]} : { [x: string]: string | (() => void) | boolean | number | number[]; [x: number]: (() => void) | number | number[]; 0: () => void; p: string; }
 
     p: "",
 >p : string
diff --git a/tests/baselines/reference/computedPropertyNamesContextualType7_ES6.types b/tests/baselines/reference/computedPropertyNamesContextualType7_ES6.types
index e98e0fb8941d6..bc6ae72fb4fe7 100644
--- a/tests/baselines/reference/computedPropertyNamesContextualType7_ES6.types
+++ b/tests/baselines/reference/computedPropertyNamesContextualType7_ES6.types
@@ -19,7 +19,7 @@ declare function foo<T>(obj: I<T>): T
 foo({
 >foo({    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]}) : (() => void) | number | number[]
 >foo : <T>(obj: I<T>) => T
->{    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]} : { [x: number]: (() => void) | number | number[]; 0: () => void; p: string; }
+>{    p: "",    0: () => { },    ["hi" + "bye"]: true,    [0 + 1]: 0,    [+"hi"]: [0]} : { [x: string]: string | (() => void) | boolean | number | number[]; [x: number]: (() => void) | number | number[]; 0: () => void; p: string; }
 
     p: "",
 >p : string
diff --git a/tests/baselines/reference/computedPropertyNamesContextualType8_ES5.errors.txt b/tests/baselines/reference/computedPropertyNamesContextualType8_ES5.errors.txt
index 3376243e3707f..ee36609095a04 100644
--- a/tests/baselines/reference/computedPropertyNamesContextualType8_ES5.errors.txt
+++ b/tests/baselines/reference/computedPropertyNamesContextualType8_ES5.errors.txt
@@ -1,4 +1,4 @@
-tests/cases/conformance/es6/computedProperties/computedPropertyNamesContextualType8_ES5.ts(6,5): error TS2322: Type '{ [x: string]: string | number; [x: number]: undefined; }' is not assignable to type 'I'.
+tests/cases/conformance/es6/computedProperties/computedPropertyNamesContextualType8_ES5.ts(6,5): error TS2322: Type '{ [x: string]: string | number; }' is not assignable to type 'I'.
   Index signatures are incompatible.
     Type 'string | number' is not assignable to type 'boolean'.
       Type 'string' is not assignable to type 'boolean'.
@@ -12,7 +12,7 @@ tests/cases/conformance/es6/computedProperties/computedPropertyNamesContextualTy
     
     var o: I = {
         ~
-!!! error TS2322: Type '{ [x: string]: string | number; [x: number]: undefined; }' is not assignable to type 'I'.
+!!! error TS2322: Type '{ [x: string]: string | number; }' is not assignable to type 'I'.
 !!! error TS2322:   Index signatures are incompatible.
 !!! error TS2322:     Type 'string | number' is not assignable to type 'boolean'.
 !!! error TS2322:       Type 'string' is not assignable to type 'boolean'.
diff --git a/tests/baselines/reference/computedPropertyNamesContextualType8_ES6.errors.txt b/tests/baselines/reference/computedPropertyNamesContextualType8_ES6.errors.txt
index e4540337ed4f0..1048fd2e119e7 100644
--- a/tests/baselines/reference/computedPropertyNamesContextualType8_ES6.errors.txt
+++ b/tests/baselines/reference/computedPropertyNamesContextualType8_ES6.errors.txt
@@ -1,4 +1,4 @@
-tests/cases/conformance/es6/computedProperties/computedPropertyNamesContextualType8_ES6.ts(6,5): error TS2322: Type '{ [x: string]: string | number; [x: number]: undefined; }' is not assignable to type 'I'.
+tests/cases/conformance/es6/computedProperties/computedPropertyNamesContextualType8_ES6.ts(6,5): error TS2322: Type '{ [x: string]: string | number; }' is not assignable to type 'I'.
   Index signatures are incompatible.
     Type 'string | number' is not assignable to type 'boolean'.
       Type 'string' is not assignable to type 'boolean'.
@@ -12,7 +12,7 @@ tests/cases/conformance/es6/computedProperties/computedPropertyNamesContextualTy
     
     var o: I = {
         ~
-!!! error TS2322: Type '{ [x: string]: string | number; [x: number]: undefined; }' is not assignable to type 'I'.
+!!! error TS2322: Type '{ [x: string]: string | number; }' is not assignable to type 'I'.
 !!! error TS2322:   Index signatures are incompatible.
 !!! error TS2322:     Type 'string | number' is not assignable to type 'boolean'.
 !!! error TS2322:       Type 'string' is not assignable to type 'boolean'.
diff --git a/tests/baselines/reference/computedPropertyNamesContextualType9_ES5.errors.txt b/tests/baselines/reference/computedPropertyNamesContextualType9_ES5.errors.txt
index d4085a37e6053..e76b3a704dc6e 100644
--- a/tests/baselines/reference/computedPropertyNamesContextualType9_ES5.errors.txt
+++ b/tests/baselines/reference/computedPropertyNamesContextualType9_ES5.errors.txt
@@ -1,4 +1,4 @@
-tests/cases/conformance/es6/computedProperties/computedPropertyNamesContextualType9_ES5.ts(6,5): error TS2322: Type '{ [x: string]: string | number; [x: number]: string | number; }' is not assignable to type 'I'.
+tests/cases/conformance/es6/computedProperties/computedPropertyNamesContextualType9_ES5.ts(6,5): error TS2322: Type '{ [x: number]: string | number; }' is not assignable to type 'I'.
   Index signatures are incompatible.
     Type 'string | number' is not assignable to type 'boolean'.
       Type 'string' is not assignable to type 'boolean'.
@@ -12,7 +12,7 @@ tests/cases/conformance/es6/computedProperties/computedPropertyNamesContextualTy
     
     var o: I = {
         ~
-!!! error TS2322: Type '{ [x: string]: string | number; [x: number]: string | number; }' is not assignable to type 'I'.
+!!! error TS2322: Type '{ [x: number]: string | number; }' is not assignable to type 'I'.
 !!! error TS2322:   Index signatures are incompatible.
 !!! error TS2322:     Type 'string | number' is not assignable to type 'boolean'.
 !!! error TS2322:       Type 'string' is not assignable to type 'boolean'.
diff --git a/tests/baselines/reference/computedPropertyNamesContextualType9_ES6.errors.txt b/tests/baselines/reference/computedPropertyNamesContextualType9_ES6.errors.txt
index eca1360c26fff..468ad400c26cc 100644
--- a/tests/baselines/reference/computedPropertyNamesContextualType9_ES6.errors.txt
+++ b/tests/baselines/reference/computedPropertyNamesContextualType9_ES6.errors.txt
@@ -1,4 +1,4 @@
-tests/cases/conformance/es6/computedProperties/computedPropertyNamesContextualType9_ES6.ts(6,5): error TS2322: Type '{ [x: string]: string | number; [x: number]: string | number; }' is not assignable to type 'I'.
+tests/cases/conformance/es6/computedProperties/computedPropertyNamesContextualType9_ES6.ts(6,5): error TS2322: Type '{ [x: number]: string | number; }' is not assignable to type 'I'.
   Index signatures are incompatible.
     Type 'string | number' is not assignable to type 'boolean'.
       Type 'string' is not assignable to type 'boolean'.
@@ -12,7 +12,7 @@ tests/cases/conformance/es6/computedProperties/computedPropertyNamesContextualTy
     
     var o: I = {
         ~
-!!! error TS2322: Type '{ [x: string]: string | number; [x: number]: string | number; }' is not assignable to type 'I'.
+!!! error TS2322: Type '{ [x: number]: string | number; }' is not assignable to type 'I'.
 !!! error TS2322:   Index signatures are incompatible.
 !!! error TS2322:     Type 'string | number' is not assignable to type 'boolean'.
 !!! error TS2322:       Type 'string' is not assignable to type 'boolean'.
diff --git a/tests/baselines/reference/computedPropertyNamesDeclarationEmit5_ES5.js b/tests/baselines/reference/computedPropertyNamesDeclarationEmit5_ES5.js
index e77eb79dc709e..f04ea61379d3e 100644
--- a/tests/baselines/reference/computedPropertyNamesDeclarationEmit5_ES5.js
+++ b/tests/baselines/reference/computedPropertyNamesDeclarationEmit5_ES5.js
@@ -26,4 +26,6 @@ var _a;
 
 
 //// [computedPropertyNamesDeclarationEmit5_ES5.d.ts]
-declare var v: {};
+declare var v: {
+    [x: string]: any;
+};
diff --git a/tests/baselines/reference/computedPropertyNamesDeclarationEmit5_ES5.types b/tests/baselines/reference/computedPropertyNamesDeclarationEmit5_ES5.types
index 62faa5c2716a8..0653059b53598 100644
--- a/tests/baselines/reference/computedPropertyNamesDeclarationEmit5_ES5.types
+++ b/tests/baselines/reference/computedPropertyNamesDeclarationEmit5_ES5.types
@@ -1,7 +1,7 @@
 === tests/cases/conformance/es6/computedProperties/computedPropertyNamesDeclarationEmit5_ES5.ts ===
 var v = {
->v : {}
->{    ["" + ""]: 0,    ["" + ""]() { },    get ["" + ""]() { return 0; },    set ["" + ""](x) { }} : {}
+>v : { [x: string]: any; }
+>{    ["" + ""]: 0,    ["" + ""]() { },    get ["" + ""]() { return 0; },    set ["" + ""](x) { }} : { [x: string]: any; }
 
     ["" + ""]: 0,
 >"" + "" : string
diff --git a/tests/baselines/reference/computedPropertyNamesDeclarationEmit5_ES6.js b/tests/baselines/reference/computedPropertyNamesDeclarationEmit5_ES6.js
index e19ac43656e56..de1f8c65d7f34 100644
--- a/tests/baselines/reference/computedPropertyNamesDeclarationEmit5_ES6.js
+++ b/tests/baselines/reference/computedPropertyNamesDeclarationEmit5_ES6.js
@@ -16,4 +16,6 @@ var v = {
 
 
 //// [computedPropertyNamesDeclarationEmit5_ES6.d.ts]
-declare var v: {};
+declare var v: {
+    [x: string]: any;
+};
diff --git a/tests/baselines/reference/computedPropertyNamesDeclarationEmit5_ES6.types b/tests/baselines/reference/computedPropertyNamesDeclarationEmit5_ES6.types
index 3eb313d268709..45d1e74f24a33 100644
--- a/tests/baselines/reference/computedPropertyNamesDeclarationEmit5_ES6.types
+++ b/tests/baselines/reference/computedPropertyNamesDeclarationEmit5_ES6.types
@@ -1,7 +1,7 @@
 === tests/cases/conformance/es6/computedProperties/computedPropertyNamesDeclarationEmit5_ES6.ts ===
 var v = {
->v : {}
->{    ["" + ""]: 0,    ["" + ""]() { },    get ["" + ""]() { return 0; },    set ["" + ""](x) { }} : {}
+>v : { [x: string]: any; }
+>{    ["" + ""]: 0,    ["" + ""]() { },    get ["" + ""]() { return 0; },    set ["" + ""](x) { }} : { [x: string]: any; }
 
     ["" + ""]: 0,
 >"" + "" : string
diff --git a/tests/baselines/reference/constEnumPropertyAccess1.types b/tests/baselines/reference/constEnumPropertyAccess1.types
index 5ed2b932bd0da..f0e00fe771771 100644
--- a/tests/baselines/reference/constEnumPropertyAccess1.types
+++ b/tests/baselines/reference/constEnumPropertyAccess1.types
@@ -35,7 +35,7 @@ var o: {
 >idx : number
 
 } = {
->{        1: true    } : { [x: number]: boolean; 1: boolean; }
+>{        1: true    } : { 1: boolean; }
 
         1: true
 >true : boolean
diff --git a/tests/baselines/reference/contextualTypeAny.errors.txt b/tests/baselines/reference/contextualTypeAny.errors.txt
new file mode 100644
index 0000000000000..09970be986ddb
--- /dev/null
+++ b/tests/baselines/reference/contextualTypeAny.errors.txt
@@ -0,0 +1,15 @@
+tests/cases/compiler/contextualTypeAny.ts(3,5): error TS2322: Type '{ p: string; q: any; }' is not assignable to type '{ [s: string]: number; }'.
+  Property 'p' is incompatible with index signature.
+    Type 'string' is not assignable to type 'number'.
+
+
+==== tests/cases/compiler/contextualTypeAny.ts (1 errors) ====
+    var x: any;
+    
+    var obj: { [s: string]: number } = { p: "", q: x };
+        ~~~
+!!! error TS2322: Type '{ p: string; q: any; }' is not assignable to type '{ [s: string]: number; }'.
+!!! error TS2322:   Property 'p' is incompatible with index signature.
+!!! error TS2322:     Type 'string' is not assignable to type 'number'.
+    
+    var arr: number[] = ["", x];
\ No newline at end of file
diff --git a/tests/baselines/reference/contextualTypeAny.symbols b/tests/baselines/reference/contextualTypeAny.symbols
deleted file mode 100644
index 5132c948a2e27..0000000000000
--- a/tests/baselines/reference/contextualTypeAny.symbols
+++ /dev/null
@@ -1,15 +0,0 @@
-=== tests/cases/compiler/contextualTypeAny.ts ===
-var x: any;
->x : Symbol(x, Decl(contextualTypeAny.ts, 0, 3))
-
-var obj: { [s: string]: number } = { p: "", q: x };
->obj : Symbol(obj, Decl(contextualTypeAny.ts, 2, 3))
->s : Symbol(s, Decl(contextualTypeAny.ts, 2, 12))
->p : Symbol(p, Decl(contextualTypeAny.ts, 2, 36))
->q : Symbol(q, Decl(contextualTypeAny.ts, 2, 43))
->x : Symbol(x, Decl(contextualTypeAny.ts, 0, 3))
-
-var arr: number[] = ["", x];
->arr : Symbol(arr, Decl(contextualTypeAny.ts, 4, 3))
->x : Symbol(x, Decl(contextualTypeAny.ts, 0, 3))
-
diff --git a/tests/baselines/reference/contextualTypeAny.types b/tests/baselines/reference/contextualTypeAny.types
deleted file mode 100644
index cace92d6567b8..0000000000000
--- a/tests/baselines/reference/contextualTypeAny.types
+++ /dev/null
@@ -1,19 +0,0 @@
-=== tests/cases/compiler/contextualTypeAny.ts ===
-var x: any;
->x : any
-
-var obj: { [s: string]: number } = { p: "", q: x };
->obj : { [s: string]: number; }
->s : string
->{ p: "", q: x } : { [x: string]: any; p: string; q: any; }
->p : string
->"" : string
->q : any
->x : any
-
-var arr: number[] = ["", x];
->arr : number[]
->["", x] : any[]
->"" : string
->x : any
-
diff --git a/tests/baselines/reference/contextualTypeArrayReturnType.types b/tests/baselines/reference/contextualTypeArrayReturnType.types
index f270b33f568a3..6c91fd7b8b964 100644
--- a/tests/baselines/reference/contextualTypeArrayReturnType.types
+++ b/tests/baselines/reference/contextualTypeArrayReturnType.types
@@ -26,18 +26,18 @@ interface Transform3D {
 var style: IBookStyle = {
 >style : IBookStyle
 >IBookStyle : IBookStyle
->{    initialLeftPageTransforms: (width: number) => {        return [            {'ry': null }        ];    }} : { initialLeftPageTransforms: (width: number) => { [x: string]: any; 'ry': any; }[]; }
+>{    initialLeftPageTransforms: (width: number) => {        return [            {'ry': null }        ];    }} : { initialLeftPageTransforms: (width: number) => { 'ry': any; }[]; }
 
     initialLeftPageTransforms: (width: number) => {
->initialLeftPageTransforms : (width: number) => { [x: string]: any; 'ry': any; }[]
->(width: number) => {        return [            {'ry': null }        ];    } : (width: number) => { [x: string]: any; 'ry': any; }[]
+>initialLeftPageTransforms : (width: number) => { 'ry': any; }[]
+>(width: number) => {        return [            {'ry': null }        ];    } : (width: number) => { 'ry': any; }[]
 >width : number
 
         return [
->[            {'ry': null }        ] : { [x: string]: null; 'ry': null; }[]
+>[            {'ry': null }        ] : { 'ry': null; }[]
 
             {'ry': null }
->{'ry': null } : { [x: string]: null; 'ry': null; }
+>{'ry': null } : { 'ry': null; }
 >null : null
 
         ];
diff --git a/tests/baselines/reference/contextualTypeWithUnionTypeIndexSignatures.types b/tests/baselines/reference/contextualTypeWithUnionTypeIndexSignatures.types
index 2f24ad082274d..965e4d21d9998 100644
--- a/tests/baselines/reference/contextualTypeWithUnionTypeIndexSignatures.types
+++ b/tests/baselines/reference/contextualTypeWithUnionTypeIndexSignatures.types
@@ -69,7 +69,7 @@ var x: IWithNoStringIndexSignature | IWithStringIndexSignature1 = { z: a => a };
 >x : IWithNoStringIndexSignature | IWithStringIndexSignature1
 >IWithNoStringIndexSignature : IWithNoStringIndexSignature
 >IWithStringIndexSignature1 : IWithStringIndexSignature1
->{ z: a => a } : { [x: string]: (a: number) => number; z: (a: number) => number; }
+>{ z: a => a } : { z: (a: number) => number; }
 >z : (a: number) => number
 >a => a : (a: number) => number
 >a : number
@@ -79,7 +79,7 @@ var x: IWithNoStringIndexSignature | IWithStringIndexSignature1 = { foo: a => a
 >x : IWithNoStringIndexSignature | IWithStringIndexSignature1
 >IWithNoStringIndexSignature : IWithNoStringIndexSignature
 >IWithStringIndexSignature1 : IWithStringIndexSignature1
->{ foo: a => a } : { [x: string]: (a: any) => any; foo: (a: any) => any; }
+>{ foo: a => a } : { foo: (a: any) => any; }
 >foo : (a: any) => any
 >a => a : (a: any) => any
 >a : any
@@ -89,7 +89,7 @@ var x: IWithNoStringIndexSignature | IWithStringIndexSignature1 = { foo: "hello"
 >x : IWithNoStringIndexSignature | IWithStringIndexSignature1
 >IWithNoStringIndexSignature : IWithNoStringIndexSignature
 >IWithStringIndexSignature1 : IWithStringIndexSignature1
->{ foo: "hello" } : { [x: string]: string; foo: string; }
+>{ foo: "hello" } : { foo: string; }
 >foo : string
 >"hello" : string
 
@@ -97,7 +97,7 @@ var x2: IWithStringIndexSignature1 | IWithStringIndexSignature2 = { z: a => a.to
 >x2 : IWithStringIndexSignature1 | IWithStringIndexSignature2
 >IWithStringIndexSignature1 : IWithStringIndexSignature1
 >IWithStringIndexSignature2 : IWithStringIndexSignature2
->{ z: a => a.toString() } : { [x: string]: (a: number) => string; z: (a: number) => string; }
+>{ z: a => a.toString() } : { z: (a: number) => string; }
 >z : (a: number) => string
 >a => a.toString() : (a: number) => string
 >a : number
@@ -110,7 +110,7 @@ var x2: IWithStringIndexSignature1 | IWithStringIndexSignature2 = { z: a => a };
 >x2 : IWithStringIndexSignature1 | IWithStringIndexSignature2
 >IWithStringIndexSignature1 : IWithStringIndexSignature1
 >IWithStringIndexSignature2 : IWithStringIndexSignature2
->{ z: a => a } : { [x: string]: (a: number) => number; z: (a: number) => number; }
+>{ z: a => a } : { z: (a: number) => number; }
 >z : (a: number) => number
 >a => a : (a: number) => number
 >a : number
@@ -124,7 +124,7 @@ var x3: IWithNoNumberIndexSignature | IWithNumberIndexSignature1 = { 1: a => a }
 >x3 : IWithNoNumberIndexSignature | IWithNumberIndexSignature1
 >IWithNoNumberIndexSignature : IWithNoNumberIndexSignature
 >IWithNumberIndexSignature1 : IWithNumberIndexSignature1
->{ 1: a => a } : { [x: number]: (a: number) => number; 1: (a: number) => number; }
+>{ 1: a => a } : { 1: (a: number) => number; }
 >a => a : (a: number) => number
 >a : number
 >a : number
@@ -133,7 +133,7 @@ var x3: IWithNoNumberIndexSignature | IWithNumberIndexSignature1 = { 0: a => a }
 >x3 : IWithNoNumberIndexSignature | IWithNumberIndexSignature1
 >IWithNoNumberIndexSignature : IWithNoNumberIndexSignature
 >IWithNumberIndexSignature1 : IWithNumberIndexSignature1
->{ 0: a => a } : { [x: number]: (a: any) => any; 0: (a: any) => any; }
+>{ 0: a => a } : { 0: (a: any) => any; }
 >a => a : (a: any) => any
 >a : any
 >a : any
@@ -142,14 +142,14 @@ var x3: IWithNoNumberIndexSignature | IWithNumberIndexSignature1 = { 0: "hello"
 >x3 : IWithNoNumberIndexSignature | IWithNumberIndexSignature1
 >IWithNoNumberIndexSignature : IWithNoNumberIndexSignature
 >IWithNumberIndexSignature1 : IWithNumberIndexSignature1
->{ 0: "hello" } : { [x: number]: string; 0: string; }
+>{ 0: "hello" } : { 0: string; }
 >"hello" : string
 
 var x4: IWithNumberIndexSignature1 | IWithNumberIndexSignature2 = { 1: a => a.toString() }; // a should be number
 >x4 : IWithNumberIndexSignature1 | IWithNumberIndexSignature2
 >IWithNumberIndexSignature1 : IWithNumberIndexSignature1
 >IWithNumberIndexSignature2 : IWithNumberIndexSignature2
->{ 1: a => a.toString() } : { [x: number]: (a: number) => string; 1: (a: number) => string; }
+>{ 1: a => a.toString() } : { 1: (a: number) => string; }
 >a => a.toString() : (a: number) => string
 >a : number
 >a.toString() : string
@@ -161,7 +161,7 @@ var x4: IWithNumberIndexSignature1 | IWithNumberIndexSignature2 = { 1: a => a };
 >x4 : IWithNumberIndexSignature1 | IWithNumberIndexSignature2
 >IWithNumberIndexSignature1 : IWithNumberIndexSignature1
 >IWithNumberIndexSignature2 : IWithNumberIndexSignature2
->{ 1: a => a } : { [x: number]: (a: number) => number; 1: (a: number) => number; }
+>{ 1: a => a } : { 1: (a: number) => number; }
 >a => a : (a: number) => number
 >a : number
 >a : number
diff --git a/tests/baselines/reference/contextualTypingOfObjectLiterals.errors.txt b/tests/baselines/reference/contextualTypingOfObjectLiterals.errors.txt
deleted file mode 100644
index ac8063a4378fc..0000000000000
--- a/tests/baselines/reference/contextualTypingOfObjectLiterals.errors.txt
+++ /dev/null
@@ -1,23 +0,0 @@
-tests/cases/compiler/contextualTypingOfObjectLiterals.ts(4,1): error TS2322: Type '{ x: string; }' is not assignable to type '{ [x: string]: string; }'.
-  Index signature is missing in type '{ x: string; }'.
-tests/cases/compiler/contextualTypingOfObjectLiterals.ts(10,3): error TS2345: Argument of type '{ x: string; }' is not assignable to parameter of type '{ [s: string]: string; }'.
-  Index signature is missing in type '{ x: string; }'.
-
-
-==== tests/cases/compiler/contextualTypingOfObjectLiterals.ts (2 errors) ====
-    var obj1: { [x: string]: string; };
-    var obj2 = {x: ""};
-    obj1 = {}; // Ok
-    obj1 = obj2; // Error - indexer doesn't match
-    ~~~~
-!!! error TS2322: Type '{ x: string; }' is not assignable to type '{ [x: string]: string; }'.
-!!! error TS2322:   Index signature is missing in type '{ x: string; }'.
-    
-    function f(x: { [s: string]: string }) { }
-    
-    f({}); // Ok
-    f(obj1); // Ok
-    f(obj2); // Error - indexer doesn't match
-      ~~~~
-!!! error TS2345: Argument of type '{ x: string; }' is not assignable to parameter of type '{ [s: string]: string; }'.
-!!! error TS2345:   Index signature is missing in type '{ x: string; }'.
\ No newline at end of file
diff --git a/tests/baselines/reference/contextualTypingOfObjectLiterals.symbols b/tests/baselines/reference/contextualTypingOfObjectLiterals.symbols
new file mode 100644
index 0000000000000..afa34cfe4818b
--- /dev/null
+++ b/tests/baselines/reference/contextualTypingOfObjectLiterals.symbols
@@ -0,0 +1,32 @@
+=== tests/cases/compiler/contextualTypingOfObjectLiterals.ts ===
+var obj1: { [x: string]: string; };
+>obj1 : Symbol(obj1, Decl(contextualTypingOfObjectLiterals.ts, 0, 3))
+>x : Symbol(x, Decl(contextualTypingOfObjectLiterals.ts, 0, 13))
+
+var obj2 = {x: ""};
+>obj2 : Symbol(obj2, Decl(contextualTypingOfObjectLiterals.ts, 1, 3))
+>x : Symbol(x, Decl(contextualTypingOfObjectLiterals.ts, 1, 12))
+
+obj1 = {}; // Ok
+>obj1 : Symbol(obj1, Decl(contextualTypingOfObjectLiterals.ts, 0, 3))
+
+obj1 = obj2; // Error - indexer doesn't match
+>obj1 : Symbol(obj1, Decl(contextualTypingOfObjectLiterals.ts, 0, 3))
+>obj2 : Symbol(obj2, Decl(contextualTypingOfObjectLiterals.ts, 1, 3))
+
+function f(x: { [s: string]: string }) { }
+>f : Symbol(f, Decl(contextualTypingOfObjectLiterals.ts, 3, 12))
+>x : Symbol(x, Decl(contextualTypingOfObjectLiterals.ts, 5, 11))
+>s : Symbol(s, Decl(contextualTypingOfObjectLiterals.ts, 5, 17))
+
+f({}); // Ok
+>f : Symbol(f, Decl(contextualTypingOfObjectLiterals.ts, 3, 12))
+
+f(obj1); // Ok
+>f : Symbol(f, Decl(contextualTypingOfObjectLiterals.ts, 3, 12))
+>obj1 : Symbol(obj1, Decl(contextualTypingOfObjectLiterals.ts, 0, 3))
+
+f(obj2); // Error - indexer doesn't match
+>f : Symbol(f, Decl(contextualTypingOfObjectLiterals.ts, 3, 12))
+>obj2 : Symbol(obj2, Decl(contextualTypingOfObjectLiterals.ts, 1, 3))
+
diff --git a/tests/baselines/reference/contextualTypingOfObjectLiterals.types b/tests/baselines/reference/contextualTypingOfObjectLiterals.types
new file mode 100644
index 0000000000000..a99fb2f39afe8
--- /dev/null
+++ b/tests/baselines/reference/contextualTypingOfObjectLiterals.types
@@ -0,0 +1,41 @@
+=== tests/cases/compiler/contextualTypingOfObjectLiterals.ts ===
+var obj1: { [x: string]: string; };
+>obj1 : { [x: string]: string; }
+>x : string
+
+var obj2 = {x: ""};
+>obj2 : { x: string; }
+>{x: ""} : { x: string; }
+>x : string
+>"" : string
+
+obj1 = {}; // Ok
+>obj1 = {} : {}
+>obj1 : { [x: string]: string; }
+>{} : {}
+
+obj1 = obj2; // Error - indexer doesn't match
+>obj1 = obj2 : { x: string; }
+>obj1 : { [x: string]: string; }
+>obj2 : { x: string; }
+
+function f(x: { [s: string]: string }) { }
+>f : (x: { [s: string]: string; }) => void
+>x : { [s: string]: string; }
+>s : string
+
+f({}); // Ok
+>f({}) : void
+>f : (x: { [s: string]: string; }) => void
+>{} : {}
+
+f(obj1); // Ok
+>f(obj1) : void
+>f : (x: { [s: string]: string; }) => void
+>obj1 : { [x: string]: string; }
+
+f(obj2); // Error - indexer doesn't match
+>f(obj2) : void
+>f : (x: { [s: string]: string; }) => void
+>obj2 : { x: string; }
+
diff --git a/tests/baselines/reference/declarationsAndAssignments.errors.txt b/tests/baselines/reference/declarationsAndAssignments.errors.txt
index 7c4671022ea4b..517eaafe4abbe 100644
--- a/tests/baselines/reference/declarationsAndAssignments.errors.txt
+++ b/tests/baselines/reference/declarationsAndAssignments.errors.txt
@@ -11,8 +11,8 @@ tests/cases/conformance/es6/destructuring/declarationsAndAssignments.ts(62,13):
 tests/cases/conformance/es6/destructuring/declarationsAndAssignments.ts(62,16): error TS2525: Initializer provides no value for this binding element and the binding element has no default value.
 tests/cases/conformance/es6/destructuring/declarationsAndAssignments.ts(63,13): error TS2525: Initializer provides no value for this binding element and the binding element has no default value.
 tests/cases/conformance/es6/destructuring/declarationsAndAssignments.ts(63,16): error TS2525: Initializer provides no value for this binding element and the binding element has no default value.
-tests/cases/conformance/es6/destructuring/declarationsAndAssignments.ts(67,9): error TS2461: Type '{ [x: number]: undefined; }' is not an array type.
-tests/cases/conformance/es6/destructuring/declarationsAndAssignments.ts(68,9): error TS2461: Type '{ [x: number]: number; 0: number; 1: number; }' is not an array type.
+tests/cases/conformance/es6/destructuring/declarationsAndAssignments.ts(67,9): error TS2461: Type '{}' is not an array type.
+tests/cases/conformance/es6/destructuring/declarationsAndAssignments.ts(68,9): error TS2461: Type '{ 0: number; 1: number; }' is not an array type.
 tests/cases/conformance/es6/destructuring/declarationsAndAssignments.ts(73,11): error TS2525: Initializer provides no value for this binding element and the binding element has no default value.
 tests/cases/conformance/es6/destructuring/declarationsAndAssignments.ts(73,14): error TS2525: Initializer provides no value for this binding element and the binding element has no default value.
 tests/cases/conformance/es6/destructuring/declarationsAndAssignments.ts(74,11): error TS2459: Type 'undefined[]' has no property 'a' and no string index signature.
@@ -122,10 +122,10 @@ tests/cases/conformance/es6/destructuring/declarationsAndAssignments.ts(138,9):
     function f9() {
         var [a, b] = {};                // Error, not array type
             ~~~~~~
-!!! error TS2461: Type '{ [x: number]: undefined; }' is not an array type.
+!!! error TS2461: Type '{}' is not an array type.
         var [c, d] = { 0: 10, 1: 20 };  // Error, not array type
             ~~~~~~
-!!! error TS2461: Type '{ [x: number]: number; 0: number; 1: number; }' is not an array type.
+!!! error TS2461: Type '{ 0: number; 1: number; }' is not an array type.
         var [e, f] = [10, 20];
     }
     
diff --git a/tests/baselines/reference/destructuringObjectBindingPatternAndAssignment1ES5.types b/tests/baselines/reference/destructuringObjectBindingPatternAndAssignment1ES5.types
index 476b5bee0cc5b..cb6052d93fd41 100644
--- a/tests/baselines/reference/destructuringObjectBindingPatternAndAssignment1ES5.types
+++ b/tests/baselines/reference/destructuringObjectBindingPatternAndAssignment1ES5.types
@@ -69,7 +69,7 @@ function foo(): F {
 >F : F
 
     return {
->{        1: true    } : { [x: number]: boolean; 1: boolean; }
+>{        1: true    } : { 1: boolean; }
 
         1: true
 >true : boolean
@@ -82,7 +82,7 @@ function bar(): F {
 >F : F
 
     return {
->{        2: true    } : { [x: number]: boolean; 2: boolean; }
+>{        2: true    } : { 2: boolean; }
 
         2: true
 >true : boolean
@@ -114,7 +114,7 @@ function foo1(): F1 {
 >F1 : F1
 
     return {
->{        "prop1": 2    } : { [x: string]: number; "prop1": number; }
+>{        "prop1": 2    } : { "prop1": number; }
 
         "prop1": 2
 >2 : number
diff --git a/tests/baselines/reference/destructuringObjectBindingPatternAndAssignment1ES6.types b/tests/baselines/reference/destructuringObjectBindingPatternAndAssignment1ES6.types
index 7a7f631eddfcf..2d77c20f65be8 100644
--- a/tests/baselines/reference/destructuringObjectBindingPatternAndAssignment1ES6.types
+++ b/tests/baselines/reference/destructuringObjectBindingPatternAndAssignment1ES6.types
@@ -69,7 +69,7 @@ function foo(): F {
 >F : F
 
     return {
->{        1: true    } : { [x: number]: boolean; 1: boolean; }
+>{        1: true    } : { 1: boolean; }
 
         1: true
 >true : boolean
@@ -82,7 +82,7 @@ function bar(): F {
 >F : F
 
     return {
->{        2: true    } : { [x: number]: boolean; 2: boolean; }
+>{        2: true    } : { 2: boolean; }
 
         2: true
 >true : boolean
@@ -114,7 +114,7 @@ function foo1(): F1 {
 >F1 : F1
 
     return {
->{        "prop1": 2    } : { [x: string]: number; "prop1": number; }
+>{        "prop1": 2    } : { "prop1": number; }
 
         "prop1": 2
 >2 : number
diff --git a/tests/baselines/reference/extendingClassFromAliasAndUsageInIndexer.types b/tests/baselines/reference/extendingClassFromAliasAndUsageInIndexer.types
index e1bfd195698d6..9825a75a220d6 100644
--- a/tests/baselines/reference/extendingClassFromAliasAndUsageInIndexer.types
+++ b/tests/baselines/reference/extendingClassFromAliasAndUsageInIndexer.types
@@ -26,7 +26,7 @@ var moduleMap: { [key: string]: IHasVisualizationModel } = {
 >moduleMap : { [key: string]: IHasVisualizationModel; }
 >key : string
 >IHasVisualizationModel : IHasVisualizationModel
->{    "moduleA": moduleA,    "moduleB": moduleB} : { [x: string]: typeof moduleA; "moduleA": typeof moduleA; "moduleB": typeof moduleB; }
+>{    "moduleA": moduleA,    "moduleB": moduleB} : { "moduleA": typeof moduleA; "moduleB": typeof moduleB; }
 
     "moduleA": moduleA,
 >moduleA : typeof moduleA
diff --git a/tests/baselines/reference/generatorTypeCheck41.types b/tests/baselines/reference/generatorTypeCheck41.types
index 926aef95ce576..0bed082dc438d 100644
--- a/tests/baselines/reference/generatorTypeCheck41.types
+++ b/tests/baselines/reference/generatorTypeCheck41.types
@@ -3,8 +3,8 @@ function* g() {
 >g : () => IterableIterator<number>
 
     let x = {
->x : {}
->{        [yield 0]: 0    } : {}
+>x : { [x: number]: number; }
+>{        [yield 0]: 0    } : { [x: number]: number; }
 
         [yield 0]: 0
 >yield 0 : any
diff --git a/tests/baselines/reference/generatorTypeCheck42.types b/tests/baselines/reference/generatorTypeCheck42.types
index 855c4697f4099..7538b8f249985 100644
--- a/tests/baselines/reference/generatorTypeCheck42.types
+++ b/tests/baselines/reference/generatorTypeCheck42.types
@@ -3,8 +3,8 @@ function* g() {
 >g : () => IterableIterator<number>
 
     let x = {
->x : {}
->{        [yield 0]() {        }    } : {}
+>x : { [x: number]: () => void; }
+>{        [yield 0]() {        }    } : { [x: number]: () => void; }
 
         [yield 0]() {
 >yield 0 : any
diff --git a/tests/baselines/reference/generatorTypeCheck43.types b/tests/baselines/reference/generatorTypeCheck43.types
index 50fc7e30c864a..a132dfcb01574 100644
--- a/tests/baselines/reference/generatorTypeCheck43.types
+++ b/tests/baselines/reference/generatorTypeCheck43.types
@@ -3,8 +3,8 @@ function* g() {
 >g : () => IterableIterator<number>
 
     let x = {
->x : {}
->{        *[yield 0]() {        }    } : {}
+>x : { [x: number]: () => IterableIterator<any>; }
+>{        *[yield 0]() {        }    } : { [x: number]: () => IterableIterator<any>; }
 
         *[yield 0]() {
 >yield 0 : any
diff --git a/tests/baselines/reference/generatorTypeCheck44.types b/tests/baselines/reference/generatorTypeCheck44.types
index 2fc67f90556ba..5c432e41cbee2 100644
--- a/tests/baselines/reference/generatorTypeCheck44.types
+++ b/tests/baselines/reference/generatorTypeCheck44.types
@@ -3,8 +3,8 @@ function* g() {
 >g : () => IterableIterator<number>
 
     let x = {
->x : {}
->{        get [yield 0]() {            return 0;        }    } : {}
+>x : { [x: number]: number; }
+>{        get [yield 0]() {            return 0;        }    } : { [x: number]: number; }
 
         get [yield 0]() {
 >yield 0 : any
diff --git a/tests/baselines/reference/genericBaseClassLiteralProperty2.types b/tests/baselines/reference/genericBaseClassLiteralProperty2.types
index d7d512165f018..3e3208249256e 100644
--- a/tests/baselines/reference/genericBaseClassLiteralProperty2.types
+++ b/tests/baselines/reference/genericBaseClassLiteralProperty2.types
@@ -14,11 +14,11 @@ class BaseCollection2<TItem extends CollectionItem2> {
 
     constructor() {
         this._itemsByKey = {};
->this._itemsByKey = {} : { [x: string]: undefined; }
+>this._itemsByKey = {} : {}
 >this._itemsByKey : { [key: string]: TItem; }
 >this : this
 >_itemsByKey : { [key: string]: TItem; }
->{} : { [x: string]: undefined; }
+>{} : {}
     }
 }
 
diff --git a/tests/baselines/reference/genericCallWithTupleType.errors.txt b/tests/baselines/reference/genericCallWithTupleType.errors.txt
index d03f8d5e68a31..bcf580320e53e 100644
--- a/tests/baselines/reference/genericCallWithTupleType.errors.txt
+++ b/tests/baselines/reference/genericCallWithTupleType.errors.txt
@@ -9,9 +9,9 @@ tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithTup
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithTupleType.ts(22,1): error TS2322: Type '[number, string]' is not assignable to type '[string, number]'.
   Types of property '0' are incompatible.
     Type 'number' is not assignable to type 'string'.
-tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithTupleType.ts(23,1): error TS2322: Type '[{ [x: number]: undefined; }, {}]' is not assignable to type '[string, number]'.
+tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithTupleType.ts(23,1): error TS2322: Type '[{}, {}]' is not assignable to type '[string, number]'.
   Types of property '0' are incompatible.
-    Type '{ [x: number]: undefined; }' is not assignable to type 'string'.
+    Type '{}' is not assignable to type 'string'.
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithTupleType.ts(24,1): error TS2322: Type '[{}]' is not assignable to type '[{}, {}]'.
   Property '1' is missing in type '[{}]'.
 
@@ -55,9 +55,9 @@ tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithTup
 !!! error TS2322:     Type 'number' is not assignable to type 'string'.
     i1.tuple1 = [{}, {}];
     ~~~~~~~~~
-!!! error TS2322: Type '[{ [x: number]: undefined; }, {}]' is not assignable to type '[string, number]'.
+!!! error TS2322: Type '[{}, {}]' is not assignable to type '[string, number]'.
 !!! error TS2322:   Types of property '0' are incompatible.
-!!! error TS2322:     Type '{ [x: number]: undefined; }' is not assignable to type 'string'.
+!!! error TS2322:     Type '{}' is not assignable to type 'string'.
     i2.tuple1 = [{}];
     ~~~~~~~~~
 !!! error TS2322: Type '[{}]' is not assignable to type '[{}, {}]'.
diff --git a/tests/baselines/reference/genericWithIndexerOfTypeParameterType1.types b/tests/baselines/reference/genericWithIndexerOfTypeParameterType1.types
index 337993dc2a69d..a316773e5c87f 100644
--- a/tests/baselines/reference/genericWithIndexerOfTypeParameterType1.types
+++ b/tests/baselines/reference/genericWithIndexerOfTypeParameterType1.types
@@ -8,7 +8,7 @@ class LazyArray<T> {
 ><{ [objectId: string]: T; }>{} : { [objectId: string]: T; }
 >objectId : string
 >T : T
->{} : { [x: string]: undefined; }
+>{} : {}
 
     array() {
 >array : () => { [objectId: string]: T; }
diff --git a/tests/baselines/reference/implicitIndexSignatures.js b/tests/baselines/reference/implicitIndexSignatures.js
new file mode 100644
index 0000000000000..6403f1f154345
--- /dev/null
+++ b/tests/baselines/reference/implicitIndexSignatures.js
@@ -0,0 +1,85 @@
+//// [implicitIndexSignatures.ts]
+type StringMap = { [x: string]: string };
+
+const empty1 = {};
+let empty2: {};
+const names1 = { a: "foo", b: "bar" };
+let names2: { a: string, b: string };
+let map: StringMap;
+map = { x: "xxx", y: "yyy" };
+map = empty1;
+map = empty2;
+map = names1;
+map = names2;
+
+declare function getStringIndexValue<T>(map: { [x: string]: T }): T;
+declare function getNumberIndexValue<T>(map: { [x: number]: T }): T;
+
+function f1() {
+    const o1 = { a: 1, b: 2 };
+    let o2: { a: number, b: number };
+    const v1 = getStringIndexValue(o1);
+    const v2 = getStringIndexValue(o2);
+}
+
+function f2() {
+    const o1 = { a: "1", b: "2" };
+    let o2: { a: string, b: string };
+    const v1 = getStringIndexValue(o1);
+    const v2 = getStringIndexValue(o2);
+}
+
+function f3() {
+    const o1 = { a: 1, b: "2" };
+    let o2: { a: number, b: string };
+    const v1 = getStringIndexValue(o1);
+    const v2 = getStringIndexValue(o2);
+}
+
+function f4() {
+    const o1 = { 0: "0", 1: "1", count: 2 };
+    let o2: { 0: string, 1: string, count: number };    
+    const v1 = getStringIndexValue(o1);
+    const v2 = getStringIndexValue(o2);
+    const v3 = getNumberIndexValue(o1);
+    const v4 = getNumberIndexValue(o2);
+}
+
+
+//// [implicitIndexSignatures.js]
+var empty1 = {};
+var empty2;
+var names1 = { a: "foo", b: "bar" };
+var names2;
+var map;
+map = { x: "xxx", y: "yyy" };
+map = empty1;
+map = empty2;
+map = names1;
+map = names2;
+function f1() {
+    var o1 = { a: 1, b: 2 };
+    var o2;
+    var v1 = getStringIndexValue(o1);
+    var v2 = getStringIndexValue(o2);
+}
+function f2() {
+    var o1 = { a: "1", b: "2" };
+    var o2;
+    var v1 = getStringIndexValue(o1);
+    var v2 = getStringIndexValue(o2);
+}
+function f3() {
+    var o1 = { a: 1, b: "2" };
+    var o2;
+    var v1 = getStringIndexValue(o1);
+    var v2 = getStringIndexValue(o2);
+}
+function f4() {
+    var o1 = { 0: "0", 1: "1", count: 2 };
+    var o2;
+    var v1 = getStringIndexValue(o1);
+    var v2 = getStringIndexValue(o2);
+    var v3 = getNumberIndexValue(o1);
+    var v4 = getNumberIndexValue(o2);
+}
diff --git a/tests/baselines/reference/implicitIndexSignatures.symbols b/tests/baselines/reference/implicitIndexSignatures.symbols
new file mode 100644
index 0000000000000..a014e7e942c2c
--- /dev/null
+++ b/tests/baselines/reference/implicitIndexSignatures.symbols
@@ -0,0 +1,166 @@
+=== tests/cases/compiler/implicitIndexSignatures.ts ===
+type StringMap = { [x: string]: string };
+>StringMap : Symbol(StringMap, Decl(implicitIndexSignatures.ts, 0, 0))
+>x : Symbol(x, Decl(implicitIndexSignatures.ts, 0, 20))
+
+const empty1 = {};
+>empty1 : Symbol(empty1, Decl(implicitIndexSignatures.ts, 2, 5))
+
+let empty2: {};
+>empty2 : Symbol(empty2, Decl(implicitIndexSignatures.ts, 3, 3))
+
+const names1 = { a: "foo", b: "bar" };
+>names1 : Symbol(names1, Decl(implicitIndexSignatures.ts, 4, 5))
+>a : Symbol(a, Decl(implicitIndexSignatures.ts, 4, 16))
+>b : Symbol(b, Decl(implicitIndexSignatures.ts, 4, 26))
+
+let names2: { a: string, b: string };
+>names2 : Symbol(names2, Decl(implicitIndexSignatures.ts, 5, 3))
+>a : Symbol(a, Decl(implicitIndexSignatures.ts, 5, 13))
+>b : Symbol(b, Decl(implicitIndexSignatures.ts, 5, 24))
+
+let map: StringMap;
+>map : Symbol(map, Decl(implicitIndexSignatures.ts, 6, 3))
+>StringMap : Symbol(StringMap, Decl(implicitIndexSignatures.ts, 0, 0))
+
+map = { x: "xxx", y: "yyy" };
+>map : Symbol(map, Decl(implicitIndexSignatures.ts, 6, 3))
+>x : Symbol(x, Decl(implicitIndexSignatures.ts, 7, 7))
+>y : Symbol(y, Decl(implicitIndexSignatures.ts, 7, 17))
+
+map = empty1;
+>map : Symbol(map, Decl(implicitIndexSignatures.ts, 6, 3))
+>empty1 : Symbol(empty1, Decl(implicitIndexSignatures.ts, 2, 5))
+
+map = empty2;
+>map : Symbol(map, Decl(implicitIndexSignatures.ts, 6, 3))
+>empty2 : Symbol(empty2, Decl(implicitIndexSignatures.ts, 3, 3))
+
+map = names1;
+>map : Symbol(map, Decl(implicitIndexSignatures.ts, 6, 3))
+>names1 : Symbol(names1, Decl(implicitIndexSignatures.ts, 4, 5))
+
+map = names2;
+>map : Symbol(map, Decl(implicitIndexSignatures.ts, 6, 3))
+>names2 : Symbol(names2, Decl(implicitIndexSignatures.ts, 5, 3))
+
+declare function getStringIndexValue<T>(map: { [x: string]: T }): T;
+>getStringIndexValue : Symbol(getStringIndexValue, Decl(implicitIndexSignatures.ts, 11, 13))
+>T : Symbol(T, Decl(implicitIndexSignatures.ts, 13, 37))
+>map : Symbol(map, Decl(implicitIndexSignatures.ts, 13, 40))
+>x : Symbol(x, Decl(implicitIndexSignatures.ts, 13, 48))
+>T : Symbol(T, Decl(implicitIndexSignatures.ts, 13, 37))
+>T : Symbol(T, Decl(implicitIndexSignatures.ts, 13, 37))
+
+declare function getNumberIndexValue<T>(map: { [x: number]: T }): T;
+>getNumberIndexValue : Symbol(getNumberIndexValue, Decl(implicitIndexSignatures.ts, 13, 68))
+>T : Symbol(T, Decl(implicitIndexSignatures.ts, 14, 37))
+>map : Symbol(map, Decl(implicitIndexSignatures.ts, 14, 40))
+>x : Symbol(x, Decl(implicitIndexSignatures.ts, 14, 48))
+>T : Symbol(T, Decl(implicitIndexSignatures.ts, 14, 37))
+>T : Symbol(T, Decl(implicitIndexSignatures.ts, 14, 37))
+
+function f1() {
+>f1 : Symbol(f1, Decl(implicitIndexSignatures.ts, 14, 68))
+
+    const o1 = { a: 1, b: 2 };
+>o1 : Symbol(o1, Decl(implicitIndexSignatures.ts, 17, 9))
+>a : Symbol(a, Decl(implicitIndexSignatures.ts, 17, 16))
+>b : Symbol(b, Decl(implicitIndexSignatures.ts, 17, 22))
+
+    let o2: { a: number, b: number };
+>o2 : Symbol(o2, Decl(implicitIndexSignatures.ts, 18, 7))
+>a : Symbol(a, Decl(implicitIndexSignatures.ts, 18, 13))
+>b : Symbol(b, Decl(implicitIndexSignatures.ts, 18, 24))
+
+    const v1 = getStringIndexValue(o1);
+>v1 : Symbol(v1, Decl(implicitIndexSignatures.ts, 19, 9))
+>getStringIndexValue : Symbol(getStringIndexValue, Decl(implicitIndexSignatures.ts, 11, 13))
+>o1 : Symbol(o1, Decl(implicitIndexSignatures.ts, 17, 9))
+
+    const v2 = getStringIndexValue(o2);
+>v2 : Symbol(v2, Decl(implicitIndexSignatures.ts, 20, 9))
+>getStringIndexValue : Symbol(getStringIndexValue, Decl(implicitIndexSignatures.ts, 11, 13))
+>o2 : Symbol(o2, Decl(implicitIndexSignatures.ts, 18, 7))
+}
+
+function f2() {
+>f2 : Symbol(f2, Decl(implicitIndexSignatures.ts, 21, 1))
+
+    const o1 = { a: "1", b: "2" };
+>o1 : Symbol(o1, Decl(implicitIndexSignatures.ts, 24, 9))
+>a : Symbol(a, Decl(implicitIndexSignatures.ts, 24, 16))
+>b : Symbol(b, Decl(implicitIndexSignatures.ts, 24, 24))
+
+    let o2: { a: string, b: string };
+>o2 : Symbol(o2, Decl(implicitIndexSignatures.ts, 25, 7))
+>a : Symbol(a, Decl(implicitIndexSignatures.ts, 25, 13))
+>b : Symbol(b, Decl(implicitIndexSignatures.ts, 25, 24))
+
+    const v1 = getStringIndexValue(o1);
+>v1 : Symbol(v1, Decl(implicitIndexSignatures.ts, 26, 9))
+>getStringIndexValue : Symbol(getStringIndexValue, Decl(implicitIndexSignatures.ts, 11, 13))
+>o1 : Symbol(o1, Decl(implicitIndexSignatures.ts, 24, 9))
+
+    const v2 = getStringIndexValue(o2);
+>v2 : Symbol(v2, Decl(implicitIndexSignatures.ts, 27, 9))
+>getStringIndexValue : Symbol(getStringIndexValue, Decl(implicitIndexSignatures.ts, 11, 13))
+>o2 : Symbol(o2, Decl(implicitIndexSignatures.ts, 25, 7))
+}
+
+function f3() {
+>f3 : Symbol(f3, Decl(implicitIndexSignatures.ts, 28, 1))
+
+    const o1 = { a: 1, b: "2" };
+>o1 : Symbol(o1, Decl(implicitIndexSignatures.ts, 31, 9))
+>a : Symbol(a, Decl(implicitIndexSignatures.ts, 31, 16))
+>b : Symbol(b, Decl(implicitIndexSignatures.ts, 31, 22))
+
+    let o2: { a: number, b: string };
+>o2 : Symbol(o2, Decl(implicitIndexSignatures.ts, 32, 7))
+>a : Symbol(a, Decl(implicitIndexSignatures.ts, 32, 13))
+>b : Symbol(b, Decl(implicitIndexSignatures.ts, 32, 24))
+
+    const v1 = getStringIndexValue(o1);
+>v1 : Symbol(v1, Decl(implicitIndexSignatures.ts, 33, 9))
+>getStringIndexValue : Symbol(getStringIndexValue, Decl(implicitIndexSignatures.ts, 11, 13))
+>o1 : Symbol(o1, Decl(implicitIndexSignatures.ts, 31, 9))
+
+    const v2 = getStringIndexValue(o2);
+>v2 : Symbol(v2, Decl(implicitIndexSignatures.ts, 34, 9))
+>getStringIndexValue : Symbol(getStringIndexValue, Decl(implicitIndexSignatures.ts, 11, 13))
+>o2 : Symbol(o2, Decl(implicitIndexSignatures.ts, 32, 7))
+}
+
+function f4() {
+>f4 : Symbol(f4, Decl(implicitIndexSignatures.ts, 35, 1))
+
+    const o1 = { 0: "0", 1: "1", count: 2 };
+>o1 : Symbol(o1, Decl(implicitIndexSignatures.ts, 38, 9))
+>count : Symbol(count, Decl(implicitIndexSignatures.ts, 38, 32))
+
+    let o2: { 0: string, 1: string, count: number };    
+>o2 : Symbol(o2, Decl(implicitIndexSignatures.ts, 39, 7))
+>count : Symbol(count, Decl(implicitIndexSignatures.ts, 39, 35))
+
+    const v1 = getStringIndexValue(o1);
+>v1 : Symbol(v1, Decl(implicitIndexSignatures.ts, 40, 9))
+>getStringIndexValue : Symbol(getStringIndexValue, Decl(implicitIndexSignatures.ts, 11, 13))
+>o1 : Symbol(o1, Decl(implicitIndexSignatures.ts, 38, 9))
+
+    const v2 = getStringIndexValue(o2);
+>v2 : Symbol(v2, Decl(implicitIndexSignatures.ts, 41, 9))
+>getStringIndexValue : Symbol(getStringIndexValue, Decl(implicitIndexSignatures.ts, 11, 13))
+>o2 : Symbol(o2, Decl(implicitIndexSignatures.ts, 39, 7))
+
+    const v3 = getNumberIndexValue(o1);
+>v3 : Symbol(v3, Decl(implicitIndexSignatures.ts, 42, 9))
+>getNumberIndexValue : Symbol(getNumberIndexValue, Decl(implicitIndexSignatures.ts, 13, 68))
+>o1 : Symbol(o1, Decl(implicitIndexSignatures.ts, 38, 9))
+
+    const v4 = getNumberIndexValue(o2);
+>v4 : Symbol(v4, Decl(implicitIndexSignatures.ts, 43, 9))
+>getNumberIndexValue : Symbol(getNumberIndexValue, Decl(implicitIndexSignatures.ts, 13, 68))
+>o2 : Symbol(o2, Decl(implicitIndexSignatures.ts, 39, 7))
+}
+
diff --git a/tests/baselines/reference/implicitIndexSignatures.types b/tests/baselines/reference/implicitIndexSignatures.types
new file mode 100644
index 0000000000000..7d335c0049107
--- /dev/null
+++ b/tests/baselines/reference/implicitIndexSignatures.types
@@ -0,0 +1,201 @@
+=== tests/cases/compiler/implicitIndexSignatures.ts ===
+type StringMap = { [x: string]: string };
+>StringMap : { [x: string]: string; }
+>x : string
+
+const empty1 = {};
+>empty1 : {}
+>{} : {}
+
+let empty2: {};
+>empty2 : {}
+
+const names1 = { a: "foo", b: "bar" };
+>names1 : { a: string; b: string; }
+>{ a: "foo", b: "bar" } : { a: string; b: string; }
+>a : string
+>"foo" : string
+>b : string
+>"bar" : string
+
+let names2: { a: string, b: string };
+>names2 : { a: string; b: string; }
+>a : string
+>b : string
+
+let map: StringMap;
+>map : { [x: string]: string; }
+>StringMap : { [x: string]: string; }
+
+map = { x: "xxx", y: "yyy" };
+>map = { x: "xxx", y: "yyy" } : { x: string; y: string; }
+>map : { [x: string]: string; }
+>{ x: "xxx", y: "yyy" } : { x: string; y: string; }
+>x : string
+>"xxx" : string
+>y : string
+>"yyy" : string
+
+map = empty1;
+>map = empty1 : {}
+>map : { [x: string]: string; }
+>empty1 : {}
+
+map = empty2;
+>map = empty2 : {}
+>map : { [x: string]: string; }
+>empty2 : {}
+
+map = names1;
+>map = names1 : { a: string; b: string; }
+>map : { [x: string]: string; }
+>names1 : { a: string; b: string; }
+
+map = names2;
+>map = names2 : { a: string; b: string; }
+>map : { [x: string]: string; }
+>names2 : { a: string; b: string; }
+
+declare function getStringIndexValue<T>(map: { [x: string]: T }): T;
+>getStringIndexValue : <T>(map: { [x: string]: T; }) => T
+>T : T
+>map : { [x: string]: T; }
+>x : string
+>T : T
+>T : T
+
+declare function getNumberIndexValue<T>(map: { [x: number]: T }): T;
+>getNumberIndexValue : <T>(map: { [x: number]: T; }) => T
+>T : T
+>map : { [x: number]: T; }
+>x : number
+>T : T
+>T : T
+
+function f1() {
+>f1 : () => void
+
+    const o1 = { a: 1, b: 2 };
+>o1 : { a: number; b: number; }
+>{ a: 1, b: 2 } : { a: number; b: number; }
+>a : number
+>1 : number
+>b : number
+>2 : number
+
+    let o2: { a: number, b: number };
+>o2 : { a: number; b: number; }
+>a : number
+>b : number
+
+    const v1 = getStringIndexValue(o1);
+>v1 : number
+>getStringIndexValue(o1) : number
+>getStringIndexValue : <T>(map: { [x: string]: T; }) => T
+>o1 : { a: number; b: number; }
+
+    const v2 = getStringIndexValue(o2);
+>v2 : number
+>getStringIndexValue(o2) : number
+>getStringIndexValue : <T>(map: { [x: string]: T; }) => T
+>o2 : { a: number; b: number; }
+}
+
+function f2() {
+>f2 : () => void
+
+    const o1 = { a: "1", b: "2" };
+>o1 : { a: string; b: string; }
+>{ a: "1", b: "2" } : { a: string; b: string; }
+>a : string
+>"1" : string
+>b : string
+>"2" : string
+
+    let o2: { a: string, b: string };
+>o2 : { a: string; b: string; }
+>a : string
+>b : string
+
+    const v1 = getStringIndexValue(o1);
+>v1 : string
+>getStringIndexValue(o1) : string
+>getStringIndexValue : <T>(map: { [x: string]: T; }) => T
+>o1 : { a: string; b: string; }
+
+    const v2 = getStringIndexValue(o2);
+>v2 : string
+>getStringIndexValue(o2) : string
+>getStringIndexValue : <T>(map: { [x: string]: T; }) => T
+>o2 : { a: string; b: string; }
+}
+
+function f3() {
+>f3 : () => void
+
+    const o1 = { a: 1, b: "2" };
+>o1 : { a: number; b: string; }
+>{ a: 1, b: "2" } : { a: number; b: string; }
+>a : number
+>1 : number
+>b : string
+>"2" : string
+
+    let o2: { a: number, b: string };
+>o2 : { a: number; b: string; }
+>a : number
+>b : string
+
+    const v1 = getStringIndexValue(o1);
+>v1 : number | string
+>getStringIndexValue(o1) : number | string
+>getStringIndexValue : <T>(map: { [x: string]: T; }) => T
+>o1 : { a: number; b: string; }
+
+    const v2 = getStringIndexValue(o2);
+>v2 : number | string
+>getStringIndexValue(o2) : number | string
+>getStringIndexValue : <T>(map: { [x: string]: T; }) => T
+>o2 : { a: number; b: string; }
+}
+
+function f4() {
+>f4 : () => void
+
+    const o1 = { 0: "0", 1: "1", count: 2 };
+>o1 : { 0: string; 1: string; count: number; }
+>{ 0: "0", 1: "1", count: 2 } : { 0: string; 1: string; count: number; }
+>"0" : string
+>"1" : string
+>count : number
+>2 : number
+
+    let o2: { 0: string, 1: string, count: number };    
+>o2 : { 0: string; 1: string; count: number; }
+>count : number
+
+    const v1 = getStringIndexValue(o1);
+>v1 : string | number
+>getStringIndexValue(o1) : string | number
+>getStringIndexValue : <T>(map: { [x: string]: T; }) => T
+>o1 : { 0: string; 1: string; count: number; }
+
+    const v2 = getStringIndexValue(o2);
+>v2 : string | number
+>getStringIndexValue(o2) : string | number
+>getStringIndexValue : <T>(map: { [x: string]: T; }) => T
+>o2 : { 0: string; 1: string; count: number; }
+
+    const v3 = getNumberIndexValue(o1);
+>v3 : string
+>getNumberIndexValue(o1) : string
+>getNumberIndexValue : <T>(map: { [x: number]: T; }) => T
+>o1 : { 0: string; 1: string; count: number; }
+
+    const v4 = getNumberIndexValue(o2);
+>v4 : string
+>getNumberIndexValue(o2) : string
+>getNumberIndexValue : <T>(map: { [x: number]: T; }) => T
+>o2 : { 0: string; 1: string; count: number; }
+}
+
diff --git a/tests/baselines/reference/indexSignaturesInferentialTyping.types b/tests/baselines/reference/indexSignaturesInferentialTyping.types
index 328dbc18e4ff3..8545a7d4ca967 100644
--- a/tests/baselines/reference/indexSignaturesInferentialTyping.types
+++ b/tests/baselines/reference/indexSignaturesInferentialTyping.types
@@ -21,15 +21,15 @@ var x1 = foo({ 0: 0, 1: 1 });       // type should be number
 >x1 : number
 >foo({ 0: 0, 1: 1 }) : number
 >foo : <T>(items: { [index: number]: T; }) => T
->{ 0: 0, 1: 1 } : { [x: number]: number; 0: number; 1: number; }
+>{ 0: 0, 1: 1 } : { 0: number; 1: number; }
 >0 : number
 >1 : number
 
 var x2 = foo({ zero: 0, one: 1 });
->x2 : any
->foo({ zero: 0, one: 1 }) : any
+>x2 : {}
+>foo({ zero: 0, one: 1 }) : {}
 >foo : <T>(items: { [index: number]: T; }) => T
->{ zero: 0, one: 1 } : { [x: number]: undefined; zero: number; one: number; }
+>{ zero: 0, one: 1 } : { zero: number; one: number; }
 >zero : number
 >0 : number
 >one : number
@@ -39,7 +39,7 @@ var x3 = bar({ 0: 0, 1: 1 });
 >x3 : number
 >bar({ 0: 0, 1: 1 }) : number
 >bar : <T>(items: { [index: string]: T; }) => T
->{ 0: 0, 1: 1 } : { [x: string]: number; 0: number; 1: number; }
+>{ 0: 0, 1: 1 } : { 0: number; 1: number; }
 >0 : number
 >1 : number
 
@@ -47,7 +47,7 @@ var x4 = bar({ zero: 0, one: 1 });  // type should be number
 >x4 : number
 >bar({ zero: 0, one: 1 }) : number
 >bar : <T>(items: { [index: string]: T; }) => T
->{ zero: 0, one: 1 } : { [x: string]: number; zero: number; one: number; }
+>{ zero: 0, one: 1 } : { zero: number; one: number; }
 >zero : number
 >0 : number
 >one : number
diff --git a/tests/baselines/reference/indexer.types b/tests/baselines/reference/indexer.types
index a0142bb93830e..f24c90f6ea142 100644
--- a/tests/baselines/reference/indexer.types
+++ b/tests/baselines/reference/indexer.types
@@ -17,7 +17,7 @@ interface JQuery {
 var jq:JQuery={ 0: { id : "a" }, 1: { id : "b" } };
 >jq : JQuery
 >JQuery : JQuery
->{ 0: { id : "a" }, 1: { id : "b" } } : { [x: number]: { id: string; }; 0: { id: string; }; 1: { id: string; }; }
+>{ 0: { id : "a" }, 1: { id : "b" } } : { 0: { id: string; }; 1: { id: string; }; }
 >{ id : "a" } : { id: string; }
 >id : string
 >"a" : string
diff --git a/tests/baselines/reference/indexer2.types b/tests/baselines/reference/indexer2.types
index 7f1ccd41cb59f..ff82707edd311 100644
--- a/tests/baselines/reference/indexer2.types
+++ b/tests/baselines/reference/indexer2.types
@@ -17,5 +17,5 @@ var directChildrenMap = <IDirectChildrenMap>{};
 >directChildrenMap : IDirectChildrenMap
 ><IDirectChildrenMap>{} : IDirectChildrenMap
 >IDirectChildrenMap : IDirectChildrenMap
->{} : { [x: number]: undefined; }
+>{} : {}
 
diff --git a/tests/baselines/reference/indexer3.types b/tests/baselines/reference/indexer3.types
index 8f0582f782ae8..28bcd9cab0c93 100644
--- a/tests/baselines/reference/indexer3.types
+++ b/tests/baselines/reference/indexer3.types
@@ -3,7 +3,7 @@ var dateMap: { [x: string]: Date; } = {}
 >dateMap : { [x: string]: Date; }
 >x : string
 >Date : Date
->{} : { [x: string]: undefined; }
+>{} : {}
 
 var r: Date = dateMap["hello"] // result type includes indexer using BCT
 >r : Date
diff --git a/tests/baselines/reference/indexerA.types b/tests/baselines/reference/indexerA.types
index c6ff81b3a26ad..ee6351eae33ac 100644
--- a/tests/baselines/reference/indexerA.types
+++ b/tests/baselines/reference/indexerA.types
@@ -17,7 +17,7 @@ class JQuery {
 var jq:JQuery={ 0: { id : "a" }, 1: { id : "b" } };
 >jq : JQuery
 >JQuery : JQuery
->{ 0: { id : "a" }, 1: { id : "b" } } : { [x: number]: { id: string; }; 0: { id: string; }; 1: { id: string; }; }
+>{ 0: { id : "a" }, 1: { id : "b" } } : { 0: { id: string; }; 1: { id: string; }; }
 >{ id : "a" } : { id: string; }
 >id : string
 >"a" : string
diff --git a/tests/baselines/reference/indexerAssignability.errors.txt b/tests/baselines/reference/indexerAssignability.errors.txt
deleted file mode 100644
index 44c2184517eca..0000000000000
--- a/tests/baselines/reference/indexerAssignability.errors.txt
+++ /dev/null
@@ -1,28 +0,0 @@
-tests/cases/compiler/indexerAssignability.ts(5,1): error TS2322: Type '{ [n: number]: string; }' is not assignable to type '{ [s: string]: string; }'.
-  Index signature is missing in type '{ [n: number]: string; }'.
-tests/cases/compiler/indexerAssignability.ts(6,1): error TS2322: Type '{}' is not assignable to type '{ [s: string]: string; }'.
-  Index signature is missing in type '{}'.
-tests/cases/compiler/indexerAssignability.ts(8,1): error TS2322: Type '{}' is not assignable to type '{ [n: number]: string; }'.
-  Index signature is missing in type '{}'.
-
-
-==== tests/cases/compiler/indexerAssignability.ts (3 errors) ====
-    var a: { [s: string]: string; };
-    var b: { [n: number]: string; };
-    var c: {};
-    
-    a = b;
-    ~
-!!! error TS2322: Type '{ [n: number]: string; }' is not assignable to type '{ [s: string]: string; }'.
-!!! error TS2322:   Index signature is missing in type '{ [n: number]: string; }'.
-    a = c;
-    ~
-!!! error TS2322: Type '{}' is not assignable to type '{ [s: string]: string; }'.
-!!! error TS2322:   Index signature is missing in type '{}'.
-    b = a;
-    b = c;
-    ~
-!!! error TS2322: Type '{}' is not assignable to type '{ [n: number]: string; }'.
-!!! error TS2322:   Index signature is missing in type '{}'.
-    c = a;
-    c = b;
\ No newline at end of file
diff --git a/tests/baselines/reference/indexerAssignability.symbols b/tests/baselines/reference/indexerAssignability.symbols
new file mode 100644
index 0000000000000..379a2885e2cbf
--- /dev/null
+++ b/tests/baselines/reference/indexerAssignability.symbols
@@ -0,0 +1,36 @@
+=== tests/cases/compiler/indexerAssignability.ts ===
+var a: { [s: string]: string; };
+>a : Symbol(a, Decl(indexerAssignability.ts, 0, 3))
+>s : Symbol(s, Decl(indexerAssignability.ts, 0, 10))
+
+var b: { [n: number]: string; };
+>b : Symbol(b, Decl(indexerAssignability.ts, 1, 3))
+>n : Symbol(n, Decl(indexerAssignability.ts, 1, 10))
+
+var c: {};
+>c : Symbol(c, Decl(indexerAssignability.ts, 2, 3))
+
+a = b;
+>a : Symbol(a, Decl(indexerAssignability.ts, 0, 3))
+>b : Symbol(b, Decl(indexerAssignability.ts, 1, 3))
+
+a = c;
+>a : Symbol(a, Decl(indexerAssignability.ts, 0, 3))
+>c : Symbol(c, Decl(indexerAssignability.ts, 2, 3))
+
+b = a;
+>b : Symbol(b, Decl(indexerAssignability.ts, 1, 3))
+>a : Symbol(a, Decl(indexerAssignability.ts, 0, 3))
+
+b = c;
+>b : Symbol(b, Decl(indexerAssignability.ts, 1, 3))
+>c : Symbol(c, Decl(indexerAssignability.ts, 2, 3))
+
+c = a;
+>c : Symbol(c, Decl(indexerAssignability.ts, 2, 3))
+>a : Symbol(a, Decl(indexerAssignability.ts, 0, 3))
+
+c = b;
+>c : Symbol(c, Decl(indexerAssignability.ts, 2, 3))
+>b : Symbol(b, Decl(indexerAssignability.ts, 1, 3))
+
diff --git a/tests/baselines/reference/indexerAssignability.types b/tests/baselines/reference/indexerAssignability.types
new file mode 100644
index 0000000000000..bd301b59224ef
--- /dev/null
+++ b/tests/baselines/reference/indexerAssignability.types
@@ -0,0 +1,42 @@
+=== tests/cases/compiler/indexerAssignability.ts ===
+var a: { [s: string]: string; };
+>a : { [s: string]: string; }
+>s : string
+
+var b: { [n: number]: string; };
+>b : { [n: number]: string; }
+>n : number
+
+var c: {};
+>c : {}
+
+a = b;
+>a = b : { [n: number]: string; }
+>a : { [s: string]: string; }
+>b : { [n: number]: string; }
+
+a = c;
+>a = c : {}
+>a : { [s: string]: string; }
+>c : {}
+
+b = a;
+>b = a : { [s: string]: string; }
+>b : { [n: number]: string; }
+>a : { [s: string]: string; }
+
+b = c;
+>b = c : {}
+>b : { [n: number]: string; }
+>c : {}
+
+c = a;
+>c = a : { [s: string]: string; }
+>c : {}
+>a : { [s: string]: string; }
+
+c = b;
+>c = b : { [n: number]: string; }
+>c : {}
+>b : { [n: number]: string; }
+
diff --git a/tests/baselines/reference/inferentialTypingObjectLiteralMethod2.types b/tests/baselines/reference/inferentialTypingObjectLiteralMethod2.types
index be937410cef0f..f70305739b896 100644
--- a/tests/baselines/reference/inferentialTypingObjectLiteralMethod2.types
+++ b/tests/baselines/reference/inferentialTypingObjectLiteralMethod2.types
@@ -30,13 +30,13 @@ foo("", { method(p1) { return p1.length } }, { method(p2) { return undefined } }
 >foo("", { method(p1) { return p1.length } }, { method(p2) { return undefined } }) : string
 >foo : <T, U>(x: T, y: Int<T, U>, z: Int<U, T>) => T
 >"" : string
->{ method(p1) { return p1.length } } : { [x: string]: (p1: string) => number; method(p1: string): number; }
+>{ method(p1) { return p1.length } } : { method(p1: string): number; }
 >method : (p1: string) => number
 >p1 : string
 >p1.length : number
 >p1 : string
 >length : number
->{ method(p2) { return undefined } } : { [x: string]: (p2: number) => any; method(p2: number): any; }
+>{ method(p2) { return undefined } } : { method(p2: number): any; }
 >method : (p2: number) => any
 >p2 : number
 >undefined : undefined
diff --git a/tests/baselines/reference/inferentialTypingUsingApparentType3.types b/tests/baselines/reference/inferentialTypingUsingApparentType3.types
index 9e0a4ceaea6de..e375fe981e89a 100644
--- a/tests/baselines/reference/inferentialTypingUsingApparentType3.types
+++ b/tests/baselines/reference/inferentialTypingUsingApparentType3.types
@@ -49,10 +49,10 @@ class ObjectField<A, T extends { [name: string]: Field<any> }> {
 }
 
 var person = new ObjectField({
->person : ObjectField<{}, { [x: string]: NumberField | CharField; id: NumberField; name: CharField; }>
->new ObjectField({    id: new NumberField(),    name: new CharField()}) : ObjectField<{}, { [x: string]: NumberField | CharField; id: NumberField; name: CharField; }>
+>person : ObjectField<{}, { id: NumberField; name: CharField; }>
+>new ObjectField({    id: new NumberField(),    name: new CharField()}) : ObjectField<{}, { id: NumberField; name: CharField; }>
 >ObjectField : typeof ObjectField
->{    id: new NumberField(),    name: new CharField()} : { [x: string]: NumberField | CharField; id: NumberField; name: CharField; }
+>{    id: new NumberField(),    name: new CharField()} : { id: NumberField; name: CharField; }
 
     id: new NumberField(),
 >id : NumberField
@@ -68,8 +68,8 @@ var person = new ObjectField({
 
 person.fields.id;
 >person.fields.id : NumberField
->person.fields : { [x: string]: NumberField | CharField; id: NumberField; name: CharField; }
->person : ObjectField<{}, { [x: string]: NumberField | CharField; id: NumberField; name: CharField; }>
->fields : { [x: string]: NumberField | CharField; id: NumberField; name: CharField; }
+>person.fields : { id: NumberField; name: CharField; }
+>person : ObjectField<{}, { id: NumberField; name: CharField; }>
+>fields : { id: NumberField; name: CharField; }
 >id : NumberField
 
diff --git a/tests/baselines/reference/interfaceContextualType.types b/tests/baselines/reference/interfaceContextualType.types
index e827f9a9d9b1e..0e835a2f1f955 100644
--- a/tests/baselines/reference/interfaceContextualType.types
+++ b/tests/baselines/reference/interfaceContextualType.types
@@ -27,11 +27,11 @@ class Bug {
 >ok : () => void
 
         this.values = {};
->this.values = {} : { [x: string]: undefined; }
+>this.values = {} : {}
 >this.values : IMap
 >this : this
 >values : IMap
->{} : { [x: string]: undefined; }
+>{} : {}
 
         this.values['comments'] = { italic: true };
 >this.values['comments'] = { italic: true } : { italic: boolean; }
@@ -48,11 +48,11 @@ class Bug {
 >shouldBeOK : () => void
 
         this.values = {
->this.values = {            comments: { italic: true }        } : { [x: string]: { italic: boolean; }; comments: { italic: boolean; }; }
+>this.values = {            comments: { italic: true }        } : { comments: { italic: boolean; }; }
 >this.values : IMap
 >this : this
 >values : IMap
->{            comments: { italic: true }        } : { [x: string]: { italic: boolean; }; comments: { italic: boolean; }; }
+>{            comments: { italic: true }        } : { comments: { italic: boolean; }; }
 
             comments: { italic: true }
 >comments : { italic: boolean; }
diff --git a/tests/baselines/reference/noErrorsInCallback.errors.txt b/tests/baselines/reference/noErrorsInCallback.errors.txt
index 90fdbbd77a55f..f0bfe00199eb0 100644
--- a/tests/baselines/reference/noErrorsInCallback.errors.txt
+++ b/tests/baselines/reference/noErrorsInCallback.errors.txt
@@ -1,5 +1,5 @@
-tests/cases/compiler/noErrorsInCallback.ts(4,19): error TS2345: Argument of type '{ [x: number]: undefined; }' is not assignable to parameter of type 'string'.
-tests/cases/compiler/noErrorsInCallback.ts(6,23): error TS2345: Argument of type '{ [x: number]: undefined; }' is not assignable to parameter of type 'string'.
+tests/cases/compiler/noErrorsInCallback.ts(4,19): error TS2345: Argument of type '{}' is not assignable to parameter of type 'string'.
+tests/cases/compiler/noErrorsInCallback.ts(6,23): error TS2345: Argument of type '{}' is not assignable to parameter of type 'string'.
 
 
 ==== tests/cases/compiler/noErrorsInCallback.ts (2 errors) ====
@@ -8,10 +8,10 @@ tests/cases/compiler/noErrorsInCallback.ts(6,23): error TS2345: Argument of type
     }
     var one = new Bar({}); // Error
                       ~~
-!!! error TS2345: Argument of type '{ [x: number]: undefined; }' is not assignable to parameter of type 'string'.
+!!! error TS2345: Argument of type '{}' is not assignable to parameter of type 'string'.
     [].forEach(() => {
         var two = new Bar({}); // No error?
                           ~~
-!!! error TS2345: Argument of type '{ [x: number]: undefined; }' is not assignable to parameter of type 'string'.
+!!! error TS2345: Argument of type '{}' is not assignable to parameter of type 'string'.
     });
      
\ No newline at end of file
diff --git a/tests/baselines/reference/noImplicitAnyIndexingSuppressed.types b/tests/baselines/reference/noImplicitAnyIndexingSuppressed.types
index b7b21bf8f9258..d82b37e0f9e5b 100644
--- a/tests/baselines/reference/noImplicitAnyIndexingSuppressed.types
+++ b/tests/baselines/reference/noImplicitAnyIndexingSuppressed.types
@@ -87,7 +87,7 @@ interface MyMap<T> {
 var m: MyMap<number> = {
 >m : MyMap<number>
 >MyMap : MyMap<T>
->{    "0": 0,    "1": 1,    "2": 2,    "Okay that's enough for today.": NaN} : { [x: string]: number; "0": number; "1": number; "2": number; "Okay that's enough for today.": number; }
+>{    "0": 0,    "1": 1,    "2": 2,    "Okay that's enough for today.": NaN} : { "0": number; "1": number; "2": number; "Okay that's enough for today.": number; }
 
     "0": 0,
 >0 : number
diff --git a/tests/baselines/reference/numericIndexerConstrainsPropertyDeclarations.errors.txt b/tests/baselines/reference/numericIndexerConstrainsPropertyDeclarations.errors.txt
index 35673eb3072a1..bb01b2fe1251b 100644
--- a/tests/baselines/reference/numericIndexerConstrainsPropertyDeclarations.errors.txt
+++ b/tests/baselines/reference/numericIndexerConstrainsPropertyDeclarations.errors.txt
@@ -5,10 +5,9 @@ tests/cases/conformance/types/objectTypeLiteral/indexSignatures/numericIndexerCo
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/numericIndexerConstrainsPropertyDeclarations.ts(36,16): error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/numericIndexerConstrainsPropertyDeclarations.ts(50,5): error TS2412: Property '2.0' of type 'number' is not assignable to numeric index type 'string'.
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/numericIndexerConstrainsPropertyDeclarations.ts(68,5): error TS2412: Property '2.0' of type 'number' is not assignable to numeric index type 'string'.
-tests/cases/conformance/types/objectTypeLiteral/indexSignatures/numericIndexerConstrainsPropertyDeclarations.ts(78,5): error TS2322: Type '{ [x: number]: string | number; 1.0: string; 2.0: number; a: string; b: number; c: () => void; "d": string; "e": number; "3.0": string; "4.0": number; f: any; X: string; foo(): string; }' is not assignable to type '{ [x: number]: string; }'.
-  Index signatures are incompatible.
-    Type 'string | number' is not assignable to type 'string'.
-      Type 'number' is not assignable to type 'string'.
+tests/cases/conformance/types/objectTypeLiteral/indexSignatures/numericIndexerConstrainsPropertyDeclarations.ts(78,5): error TS2322: Type '{ 1.0: string; 2.0: number; a: string; b: number; c: () => void; "d": string; "e": number; "3.0": string; "4.0": number; f: any; X: string; foo(): string; }' is not assignable to type '{ [x: number]: string; }'.
+  Property '2.0' is incompatible with index signature.
+    Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/numericIndexerConstrainsPropertyDeclarations.ts(88,9): error TS2304: Cannot find name 'Myn'.
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/numericIndexerConstrainsPropertyDeclarations.ts(90,9): error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/numericIndexerConstrainsPropertyDeclarations.ts(93,9): error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
@@ -108,10 +107,9 @@ tests/cases/conformance/types/objectTypeLiteral/indexSignatures/numericIndexerCo
     // error
     var b: { [x: number]: string; } = {
         ~
-!!! error TS2322: Type '{ [x: number]: string | number; 1.0: string; 2.0: number; a: string; b: number; c: () => void; "d": string; "e": number; "3.0": string; "4.0": number; f: any; X: string; foo(): string; }' is not assignable to type '{ [x: number]: string; }'.
-!!! error TS2322:   Index signatures are incompatible.
-!!! error TS2322:     Type 'string | number' is not assignable to type 'string'.
-!!! error TS2322:       Type 'number' is not assignable to type 'string'.
+!!! error TS2322: Type '{ 1.0: string; 2.0: number; a: string; b: number; c: () => void; "d": string; "e": number; "3.0": string; "4.0": number; f: any; X: string; foo(): string; }' is not assignable to type '{ [x: number]: string; }'.
+!!! error TS2322:   Property '2.0' is incompatible with index signature.
+!!! error TS2322:     Type 'number' is not assignable to type 'string'.
         a: '',
         b: 1, 
         c: () => { }, 
diff --git a/tests/baselines/reference/numericIndexerConstrainsPropertyDeclarations2.errors.txt b/tests/baselines/reference/numericIndexerConstrainsPropertyDeclarations2.errors.txt
index ff18160e9a50e..332b356c732e1 100644
--- a/tests/baselines/reference/numericIndexerConstrainsPropertyDeclarations2.errors.txt
+++ b/tests/baselines/reference/numericIndexerConstrainsPropertyDeclarations2.errors.txt
@@ -1,10 +1,9 @@
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/numericIndexerConstrainsPropertyDeclarations2.ts(16,5): error TS2412: Property '3.0' of type 'number' is not assignable to numeric index type 'A'.
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/numericIndexerConstrainsPropertyDeclarations2.ts(25,5): error TS2412: Property '3.0' of type 'number' is not assignable to numeric index type 'A'.
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/numericIndexerConstrainsPropertyDeclarations2.ts(34,5): error TS2412: Property '3.0' of type 'number' is not assignable to numeric index type 'A'.
-tests/cases/conformance/types/objectTypeLiteral/indexSignatures/numericIndexerConstrainsPropertyDeclarations2.ts(39,5): error TS2322: Type '{ [x: number]: A | number; 1.0: A; 2.0: B; 3.0: number; "2.5": B; "4.0": string; }' is not assignable to type '{ [x: number]: A; }'.
-  Index signatures are incompatible.
-    Type 'A | number' is not assignable to type 'A'.
-      Type 'number' is not assignable to type 'A'.
+tests/cases/conformance/types/objectTypeLiteral/indexSignatures/numericIndexerConstrainsPropertyDeclarations2.ts(39,5): error TS2322: Type '{ 1.0: A; 2.0: B; 3.0: number; "2.5": B; "4.0": string; }' is not assignable to type '{ [x: number]: A; }'.
+  Property '3.0' is incompatible with index signature.
+    Type 'number' is not assignable to type 'A'.
 
 
 ==== tests/cases/conformance/types/objectTypeLiteral/indexSignatures/numericIndexerConstrainsPropertyDeclarations2.ts (4 errors) ====
@@ -54,10 +53,9 @@ tests/cases/conformance/types/objectTypeLiteral/indexSignatures/numericIndexerCo
     // error
     var b: { [x: number]: A } = {
         ~
-!!! error TS2322: Type '{ [x: number]: A | number; 1.0: A; 2.0: B; 3.0: number; "2.5": B; "4.0": string; }' is not assignable to type '{ [x: number]: A; }'.
-!!! error TS2322:   Index signatures are incompatible.
-!!! error TS2322:     Type 'A | number' is not assignable to type 'A'.
-!!! error TS2322:       Type 'number' is not assignable to type 'A'.
+!!! error TS2322: Type '{ 1.0: A; 2.0: B; 3.0: number; "2.5": B; "4.0": string; }' is not assignable to type '{ [x: number]: A; }'.
+!!! error TS2322:   Property '3.0' is incompatible with index signature.
+!!! error TS2322:     Type 'number' is not assignable to type 'A'.
         1.0: new A(), 
         2.0: new B(), 
         "2.5": new B(),
diff --git a/tests/baselines/reference/numericIndexerConstraint2.errors.txt b/tests/baselines/reference/numericIndexerConstraint2.errors.txt
index 385efbcead2ab..5c0337acc3247 100644
--- a/tests/baselines/reference/numericIndexerConstraint2.errors.txt
+++ b/tests/baselines/reference/numericIndexerConstraint2.errors.txt
@@ -1,5 +1,6 @@
 tests/cases/compiler/numericIndexerConstraint2.ts(4,1): error TS2322: Type '{ one: number; }' is not assignable to type '{ [index: string]: Foo; }'.
-  Index signature is missing in type '{ one: number; }'.
+  Property 'one' is incompatible with index signature.
+    Type 'number' is not assignable to type 'Foo'.
 
 
 ==== tests/cases/compiler/numericIndexerConstraint2.ts (1 errors) ====
@@ -9,4 +10,5 @@ tests/cases/compiler/numericIndexerConstraint2.ts(4,1): error TS2322: Type '{ on
     x = a;
     ~
 !!! error TS2322: Type '{ one: number; }' is not assignable to type '{ [index: string]: Foo; }'.
-!!! error TS2322:   Index signature is missing in type '{ one: number; }'.
\ No newline at end of file
+!!! error TS2322:   Property 'one' is incompatible with index signature.
+!!! error TS2322:     Type 'number' is not assignable to type 'Foo'.
\ No newline at end of file
diff --git a/tests/baselines/reference/numericIndexerConstraint4.types b/tests/baselines/reference/numericIndexerConstraint4.types
index 97e72b5088d93..c8af4d54a9a75 100644
--- a/tests/baselines/reference/numericIndexerConstraint4.types
+++ b/tests/baselines/reference/numericIndexerConstraint4.types
@@ -22,7 +22,7 @@ var x: {
 >A : A
 
 } = { data: new B() }
->{ data: new B() } : { [x: number]: undefined; data: B; }
+>{ data: new B() } : { data: B; }
 >data : B
 >new B() : B
 >B : typeof B
diff --git a/tests/baselines/reference/numericIndexerConstraint5.errors.txt b/tests/baselines/reference/numericIndexerConstraint5.errors.txt
index 98acc65eeb73c..cb888de08c4ec 100644
--- a/tests/baselines/reference/numericIndexerConstraint5.errors.txt
+++ b/tests/baselines/reference/numericIndexerConstraint5.errors.txt
@@ -1,5 +1,6 @@
 tests/cases/compiler/numericIndexerConstraint5.ts(2,5): error TS2322: Type '{ 0: Date; name: string; }' is not assignable to type '{ [name: number]: string; }'.
-  Index signature is missing in type '{ 0: Date; name: string; }'.
+  Property '0' is incompatible with index signature.
+    Type 'Date' is not assignable to type 'string'.
 
 
 ==== tests/cases/compiler/numericIndexerConstraint5.ts (1 errors) ====
@@ -7,4 +8,5 @@ tests/cases/compiler/numericIndexerConstraint5.ts(2,5): error TS2322: Type '{ 0:
     var z: { [name: number]: string } = x;
         ~
 !!! error TS2322: Type '{ 0: Date; name: string; }' is not assignable to type '{ [name: number]: string; }'.
-!!! error TS2322:   Index signature is missing in type '{ 0: Date; name: string; }'.
\ No newline at end of file
+!!! error TS2322:   Property '0' is incompatible with index signature.
+!!! error TS2322:     Type 'Date' is not assignable to type 'string'.
\ No newline at end of file
diff --git a/tests/baselines/reference/numericIndexingResults.types b/tests/baselines/reference/numericIndexingResults.types
index 560bbdc74a8e7..9a060b388e363 100644
--- a/tests/baselines/reference/numericIndexingResults.types
+++ b/tests/baselines/reference/numericIndexingResults.types
@@ -151,7 +151,7 @@ var r6 = a[3];
 var b: { [x: number]: string } = { 1: '', "2": '' }
 >b : { [x: number]: string; }
 >x : number
->{ 1: '', "2": '' } : { [x: number]: string; 1: string; "2": string; }
+>{ 1: '', "2": '' } : { 1: string; "2": string; }
 >'' : string
 >'' : string
 
@@ -194,7 +194,7 @@ var r6 = b[3];
 var b2: { [x: number]: string; 1: string; "2": string; } = { 1: '', "2": '' }
 >b2 : { [x: number]: string; 1: string; "2": string; }
 >x : number
->{ 1: '', "2": '' } : { [x: number]: string; 1: string; "2": string; }
+>{ 1: '', "2": '' } : { 1: string; "2": string; }
 >'' : string
 >'' : string
 
diff --git a/tests/baselines/reference/objectIndexer.types b/tests/baselines/reference/objectIndexer.types
index 3dcd7bcb77e96..b11c475a3863d 100644
--- a/tests/baselines/reference/objectIndexer.types
+++ b/tests/baselines/reference/objectIndexer.types
@@ -23,11 +23,11 @@ class Emitter {
 
     constructor () {
         this.listeners = {};
->this.listeners = {} : { [x: string]: undefined; }
+>this.listeners = {} : {}
 >this.listeners : IMap
 >this : this
 >listeners : IMap
->{} : { [x: string]: undefined; }
+>{} : {}
     }
 }
 
diff --git a/tests/baselines/reference/objectLiteralIndexerErrors.errors.txt b/tests/baselines/reference/objectLiteralIndexerErrors.errors.txt
index f825c41631149..9d5ff7ea0a2ba 100644
--- a/tests/baselines/reference/objectLiteralIndexerErrors.errors.txt
+++ b/tests/baselines/reference/objectLiteralIndexerErrors.errors.txt
@@ -1,10 +1,13 @@
-tests/cases/compiler/objectLiteralIndexerErrors.ts(13,5): error TS2322: Type '{ [x: string]: A; [x: number]: A; 0: A; x: B; }' is not assignable to type '{ [s: string]: A; [n: number]: B; }'.
-  Index signatures are incompatible.
+tests/cases/compiler/objectLiteralIndexerErrors.ts(13,5): error TS2322: Type '{ 0: A; x: B; }' is not assignable to type '{ [s: string]: A; [n: number]: B; }'.
+  Property '0' is incompatible with index signature.
     Type 'A' is not assignable to type 'B'.
       Property 'y' is missing in type 'A'.
+tests/cases/compiler/objectLiteralIndexerErrors.ts(14,1): error TS2322: Type '{ 0: A; x: any; }' is not assignable to type '{ [s: string]: A; [n: number]: B; }'.
+  Property '0' is incompatible with index signature.
+    Type 'A' is not assignable to type 'B'.
 
 
-==== tests/cases/compiler/objectLiteralIndexerErrors.ts (1 errors) ====
+==== tests/cases/compiler/objectLiteralIndexerErrors.ts (2 errors) ====
     interface A {
         x: number;
     }
@@ -19,8 +22,12 @@ tests/cases/compiler/objectLiteralIndexerErrors.ts(13,5): error TS2322: Type '{
     
     var o1: { [s: string]: A;[n: number]: B; } = { x: b, 0: a }; // both indexers are A
         ~~
-!!! error TS2322: Type '{ [x: string]: A; [x: number]: A; 0: A; x: B; }' is not assignable to type '{ [s: string]: A; [n: number]: B; }'.
-!!! error TS2322:   Index signatures are incompatible.
+!!! error TS2322: Type '{ 0: A; x: B; }' is not assignable to type '{ [s: string]: A; [n: number]: B; }'.
+!!! error TS2322:   Property '0' is incompatible with index signature.
 !!! error TS2322:     Type 'A' is not assignable to type 'B'.
 !!! error TS2322:       Property 'y' is missing in type 'A'.
-    o1 = { x: c, 0: a }; // string indexer is any, number indexer is A
\ No newline at end of file
+    o1 = { x: c, 0: a }; // string indexer is any, number indexer is A
+    ~~
+!!! error TS2322: Type '{ 0: A; x: any; }' is not assignable to type '{ [s: string]: A; [n: number]: B; }'.
+!!! error TS2322:   Property '0' is incompatible with index signature.
+!!! error TS2322:     Type 'A' is not assignable to type 'B'.
\ No newline at end of file
diff --git a/tests/baselines/reference/objectLiteralIndexerNoImplicitAny.types b/tests/baselines/reference/objectLiteralIndexerNoImplicitAny.types
index a49f76d02e91e..b0ddd9f60d0e9 100644
--- a/tests/baselines/reference/objectLiteralIndexerNoImplicitAny.types
+++ b/tests/baselines/reference/objectLiteralIndexerNoImplicitAny.types
@@ -9,7 +9,7 @@ interface I {
 var x: I = {
 >x : I
 >I : I
->{    p: null} : { [x: string]: null; p: null; }
+>{    p: null} : { p: null; }
 
     p: null
 >p : null
diff --git a/tests/baselines/reference/objectLiteralIndexers.types b/tests/baselines/reference/objectLiteralIndexers.types
index d5add00ebafb6..9e3aa4bac49c3 100644
--- a/tests/baselines/reference/objectLiteralIndexers.types
+++ b/tests/baselines/reference/objectLiteralIndexers.types
@@ -31,23 +31,23 @@ var o1: { [s: string]: A;[n: number]: B; } = { x: a, 0: b }; // string indexer i
 >A : A
 >n : number
 >B : B
->{ x: a, 0: b } : { [x: string]: A; [x: number]: B; 0: B; x: A; }
+>{ x: a, 0: b } : { 0: B; x: A; }
 >x : A
 >a : A
 >b : B
 
 o1 = { x: b, 0: c }; // both indexers are any
->o1 = { x: b, 0: c } : { [x: string]: any; [x: number]: any; 0: any; x: B; }
+>o1 = { x: b, 0: c } : { 0: any; x: B; }
 >o1 : { [s: string]: A; [n: number]: B; }
->{ x: b, 0: c } : { [x: string]: any; [x: number]: any; 0: any; x: B; }
+>{ x: b, 0: c } : { 0: any; x: B; }
 >x : B
 >b : B
 >c : any
 
 o1 = { x: c, 0: b }; // string indexer is any, number indexer is B
->o1 = { x: c, 0: b } : { [x: string]: any; [x: number]: B; 0: B; x: any; }
+>o1 = { x: c, 0: b } : { 0: B; x: any; }
 >o1 : { [s: string]: A; [n: number]: B; }
->{ x: c, 0: b } : { [x: string]: any; [x: number]: B; 0: B; x: any; }
+>{ x: c, 0: b } : { 0: B; x: any; }
 >x : any
 >c : any
 >b : B
diff --git a/tests/baselines/reference/objectTypesIdentityWithNumericIndexers1.types b/tests/baselines/reference/objectTypesIdentityWithNumericIndexers1.types
index 2284d06ffbd0f..c5de5c7b9b453 100644
--- a/tests/baselines/reference/objectTypesIdentityWithNumericIndexers1.types
+++ b/tests/baselines/reference/objectTypesIdentityWithNumericIndexers1.types
@@ -50,7 +50,7 @@ var a: {
 var b: { [x: number]: string; } = { foo: '' };
 >b : { [x: number]: string; }
 >x : number
->{ foo: '' } : { [x: number]: undefined; foo: string; }
+>{ foo: '' } : { foo: string; }
 >foo : string
 >'' : string
 
diff --git a/tests/baselines/reference/objectTypesIdentityWithNumericIndexers2.types b/tests/baselines/reference/objectTypesIdentityWithNumericIndexers2.types
index 1a580297b1b3e..17fc6a07a005a 100644
--- a/tests/baselines/reference/objectTypesIdentityWithNumericIndexers2.types
+++ b/tests/baselines/reference/objectTypesIdentityWithNumericIndexers2.types
@@ -64,7 +64,7 @@ var b: { [x: number]: Derived; } = { foo: <Derived>null };
 >b : { [x: number]: Derived; }
 >x : number
 >Derived : Derived
->{ foo: <Derived>null } : { [x: number]: undefined; foo: Derived; }
+>{ foo: <Derived>null } : { foo: Derived; }
 >foo : Derived
 ><Derived>null : Derived
 >Derived : Derived
diff --git a/tests/baselines/reference/objectTypesIdentityWithNumericIndexers3.types b/tests/baselines/reference/objectTypesIdentityWithNumericIndexers3.types
index ae384bbb4db36..99e6b8c86326e 100644
--- a/tests/baselines/reference/objectTypesIdentityWithNumericIndexers3.types
+++ b/tests/baselines/reference/objectTypesIdentityWithNumericIndexers3.types
@@ -50,7 +50,7 @@ var a: {
 var b: { [x: number]: string; } = { foo: '' };
 >b : { [x: number]: string; }
 >x : number
->{ foo: '' } : { [x: number]: undefined; foo: string; }
+>{ foo: '' } : { foo: string; }
 >foo : string
 >'' : string
 
diff --git a/tests/baselines/reference/objectTypesIdentityWithStringIndexers.types b/tests/baselines/reference/objectTypesIdentityWithStringIndexers.types
index a7eeb67250477..8393eaf68a0dd 100644
--- a/tests/baselines/reference/objectTypesIdentityWithStringIndexers.types
+++ b/tests/baselines/reference/objectTypesIdentityWithStringIndexers.types
@@ -50,7 +50,7 @@ var a: {
 var b: { [x: string]: string; } = { foo: '' };
 >b : { [x: string]: string; }
 >x : string
->{ foo: '' } : { [x: string]: string; foo: string; }
+>{ foo: '' } : { foo: string; }
 >foo : string
 >'' : string
 
diff --git a/tests/baselines/reference/objectTypesIdentityWithStringIndexers2.types b/tests/baselines/reference/objectTypesIdentityWithStringIndexers2.types
index d13942521170d..814d0c91814f6 100644
--- a/tests/baselines/reference/objectTypesIdentityWithStringIndexers2.types
+++ b/tests/baselines/reference/objectTypesIdentityWithStringIndexers2.types
@@ -64,7 +64,7 @@ var b: { [x: string]: Derived; } = { foo: <Derived>null };
 >b : { [x: string]: Derived; }
 >x : string
 >Derived : Derived
->{ foo: <Derived>null } : { [x: string]: Derived; foo: Derived; }
+>{ foo: <Derived>null } : { foo: Derived; }
 >foo : Derived
 ><Derived>null : Derived
 >Derived : Derived
diff --git a/tests/baselines/reference/operatorsAndIntersectionTypes.types b/tests/baselines/reference/operatorsAndIntersectionTypes.types
index 70611776fc1cd..6b5987d3a69da 100644
--- a/tests/baselines/reference/operatorsAndIntersectionTypes.types
+++ b/tests/baselines/reference/operatorsAndIntersectionTypes.types
@@ -28,7 +28,7 @@ function createSerialNo() {
 let map1: { [x: string]: number } = {};
 >map1 : { [x: string]: number; }
 >x : string
->{} : { [x: string]: undefined; }
+>{} : {}
 
 let guid = createGuid();
 >guid : string & { $Guid: any; }
@@ -45,7 +45,7 @@ map1[guid] = 123;  // Can with tagged string
 let map2: { [x: number]: string } = {};
 >map2 : { [x: number]: string; }
 >x : number
->{} : { [x: number]: undefined; }
+>{} : {}
 
 let serialNo = createSerialNo();
 >serialNo : number & { $SerialNo: any; }
diff --git a/tests/baselines/reference/restElementWithNullInitializer.errors.txt b/tests/baselines/reference/restElementWithNullInitializer.errors.txt
index 7beb7b9a642ff..4658acc5ff40a 100644
--- a/tests/baselines/reference/restElementWithNullInitializer.errors.txt
+++ b/tests/baselines/reference/restElementWithNullInitializer.errors.txt
@@ -1,6 +1,6 @@
 tests/cases/conformance/es6/destructuring/restElementWithNullInitializer.ts(1,15): error TS2461: Type 'null' is not an array type.
 tests/cases/conformance/es6/destructuring/restElementWithNullInitializer.ts(4,15): error TS2461: Type 'undefined' is not an array type.
-tests/cases/conformance/es6/destructuring/restElementWithNullInitializer.ts(7,15): error TS2461: Type '{ [x: number]: undefined; }' is not an array type.
+tests/cases/conformance/es6/destructuring/restElementWithNullInitializer.ts(7,15): error TS2461: Type '{}' is not an array type.
 
 
 ==== tests/cases/conformance/es6/destructuring/restElementWithNullInitializer.ts (3 errors) ====
@@ -16,7 +16,7 @@ tests/cases/conformance/es6/destructuring/restElementWithNullInitializer.ts(7,15
     
     function foo3([...r] = {}) {
                   ~~~~~~
-!!! error TS2461: Type '{ [x: number]: undefined; }' is not an array type.
+!!! error TS2461: Type '{}' is not an array type.
     }
     
     function foo4([...r] = []) {
diff --git a/tests/baselines/reference/stringIndexerAssignments1.errors.txt b/tests/baselines/reference/stringIndexerAssignments1.errors.txt
index 908371bc7dd0e..ac99b239779af 100644
--- a/tests/baselines/reference/stringIndexerAssignments1.errors.txt
+++ b/tests/baselines/reference/stringIndexerAssignments1.errors.txt
@@ -1,18 +1,13 @@
-tests/cases/compiler/stringIndexerAssignments1.ts(4,1): error TS2322: Type '{ one: string; }' is not assignable to type '{ [index: string]: string; one: string; }'.
-  Index signature is missing in type '{ one: string; }'.
 tests/cases/compiler/stringIndexerAssignments1.ts(5,1): error TS2322: Type '{ one: number; two: string; }' is not assignable to type '{ [index: string]: string; one: string; }'.
   Types of property 'one' are incompatible.
     Type 'number' is not assignable to type 'string'.
 
 
-==== tests/cases/compiler/stringIndexerAssignments1.ts (2 errors) ====
+==== tests/cases/compiler/stringIndexerAssignments1.ts (1 errors) ====
     var x: { [index: string]: string; one: string; };
     var a: { one: string; };
     var b: { one: number; two: string; };
     x = a;
-    ~
-!!! error TS2322: Type '{ one: string; }' is not assignable to type '{ [index: string]: string; one: string; }'.
-!!! error TS2322:   Index signature is missing in type '{ one: string; }'.
     x = b; // error
     ~
 !!! error TS2322: Type '{ one: number; two: string; }' is not assignable to type '{ [index: string]: string; one: string; }'.
diff --git a/tests/baselines/reference/stringIndexerConstrainsPropertyDeclarations.errors.txt b/tests/baselines/reference/stringIndexerConstrainsPropertyDeclarations.errors.txt
index 08881be2a8617..8f4bbe2025a52 100644
--- a/tests/baselines/reference/stringIndexerConstrainsPropertyDeclarations.errors.txt
+++ b/tests/baselines/reference/stringIndexerConstrainsPropertyDeclarations.errors.txt
@@ -22,10 +22,9 @@ tests/cases/conformance/types/objectTypeLiteral/indexSignatures/stringIndexerCon
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/stringIndexerConstrainsPropertyDeclarations.ts(71,5): error TS2411: Property 'foo' of type '() => string' is not assignable to string index type 'string'.
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/stringIndexerConstrainsPropertyDeclarations.ts(73,5): error TS2411: Property '"4.0"' of type 'number' is not assignable to string index type 'string'.
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/stringIndexerConstrainsPropertyDeclarations.ts(74,5): error TS2411: Property 'f' of type 'MyString' is not assignable to string index type 'string'.
-tests/cases/conformance/types/objectTypeLiteral/indexSignatures/stringIndexerConstrainsPropertyDeclarations.ts(78,5): error TS2322: Type '{ [x: string]: string | number | (() => void) | MyString; 1.0: string; 2.0: number; a: string; b: number; c: () => void; "d": string; "e": number; "3.0": string; "4.0": number; f: MyString; X: string; foo(): string; }' is not assignable to type '{ [x: string]: string; }'.
-  Index signatures are incompatible.
-    Type 'string | number | (() => void) | MyString' is not assignable to type 'string'.
-      Type 'number' is not assignable to type 'string'.
+tests/cases/conformance/types/objectTypeLiteral/indexSignatures/stringIndexerConstrainsPropertyDeclarations.ts(78,5): error TS2322: Type '{ 1.0: string; 2.0: number; a: string; b: number; c: () => void; "d": string; "e": number; "3.0": string; "4.0": number; f: MyString; X: string; foo(): string; }' is not assignable to type '{ [x: string]: string; }'.
+  Property '2.0' is incompatible with index signature.
+    Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/stringIndexerConstrainsPropertyDeclarations.ts(90,9): error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/stringIndexerConstrainsPropertyDeclarations.ts(93,9): error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
 
@@ -158,10 +157,9 @@ tests/cases/conformance/types/objectTypeLiteral/indexSignatures/stringIndexerCon
     // error
     var b: { [x: string]: string; } = {
         ~
-!!! error TS2322: Type '{ [x: string]: string | number | (() => void) | MyString; 1.0: string; 2.0: number; a: string; b: number; c: () => void; "d": string; "e": number; "3.0": string; "4.0": number; f: MyString; X: string; foo(): string; }' is not assignable to type '{ [x: string]: string; }'.
-!!! error TS2322:   Index signatures are incompatible.
-!!! error TS2322:     Type 'string | number | (() => void) | MyString' is not assignable to type 'string'.
-!!! error TS2322:       Type 'number' is not assignable to type 'string'.
+!!! error TS2322: Type '{ 1.0: string; 2.0: number; a: string; b: number; c: () => void; "d": string; "e": number; "3.0": string; "4.0": number; f: MyString; X: string; foo(): string; }' is not assignable to type '{ [x: string]: string; }'.
+!!! error TS2322:   Property '2.0' is incompatible with index signature.
+!!! error TS2322:     Type 'number' is not assignable to type 'string'.
         a: '',
         b: 1, 
         c: () => { }, 
diff --git a/tests/baselines/reference/stringIndexerConstrainsPropertyDeclarations2.errors.txt b/tests/baselines/reference/stringIndexerConstrainsPropertyDeclarations2.errors.txt
index faef790545368..dacfb1a522d77 100644
--- a/tests/baselines/reference/stringIndexerConstrainsPropertyDeclarations2.errors.txt
+++ b/tests/baselines/reference/stringIndexerConstrainsPropertyDeclarations2.errors.txt
@@ -4,8 +4,8 @@ tests/cases/conformance/types/objectTypeLiteral/indexSignatures/stringIndexerCon
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/stringIndexerConstrainsPropertyDeclarations2.ts(24,5): error TS2411: Property 'd' of type 'string' is not assignable to string index type 'A'.
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/stringIndexerConstrainsPropertyDeclarations2.ts(31,5): error TS2411: Property 'c' of type 'number' is not assignable to string index type 'A'.
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/stringIndexerConstrainsPropertyDeclarations2.ts(32,5): error TS2411: Property 'd' of type 'string' is not assignable to string index type 'A'.
-tests/cases/conformance/types/objectTypeLiteral/indexSignatures/stringIndexerConstrainsPropertyDeclarations2.ts(36,5): error TS2322: Type '{ [x: string]: typeof A; a: typeof A; b: typeof B; }' is not assignable to type '{ [x: string]: A; }'.
-  Index signatures are incompatible.
+tests/cases/conformance/types/objectTypeLiteral/indexSignatures/stringIndexerConstrainsPropertyDeclarations2.ts(36,5): error TS2322: Type '{ a: typeof A; b: typeof B; }' is not assignable to type '{ [x: string]: A; }'.
+  Property 'a' is incompatible with index signature.
     Type 'typeof A' is not assignable to type 'A'.
       Property 'foo' is missing in type 'typeof A'.
 
@@ -60,8 +60,8 @@ tests/cases/conformance/types/objectTypeLiteral/indexSignatures/stringIndexerCon
     // error
     var b: { [x: string]: A } = {
         ~
-!!! error TS2322: Type '{ [x: string]: typeof A; a: typeof A; b: typeof B; }' is not assignable to type '{ [x: string]: A; }'.
-!!! error TS2322:   Index signatures are incompatible.
+!!! error TS2322: Type '{ a: typeof A; b: typeof B; }' is not assignable to type '{ [x: string]: A; }'.
+!!! error TS2322:   Property 'a' is incompatible with index signature.
 !!! error TS2322:     Type 'typeof A' is not assignable to type 'A'.
 !!! error TS2322:       Property 'foo' is missing in type 'typeof A'.
         a: A,
diff --git a/tests/baselines/reference/stringIndexingResults.types b/tests/baselines/reference/stringIndexingResults.types
index 9f613312e5a7c..1fdc580b1a2cd 100644
--- a/tests/baselines/reference/stringIndexingResults.types
+++ b/tests/baselines/reference/stringIndexingResults.types
@@ -95,7 +95,7 @@ var r9 = a[1];
 var b: { [x: string]: string } = { y: '' }
 >b : { [x: string]: string; }
 >x : string
->{ y: '' } : { [x: string]: string; y: string; }
+>{ y: '' } : { y: string; }
 >y : string
 >'' : string
 
diff --git a/tests/baselines/reference/symbolProperty1.types b/tests/baselines/reference/symbolProperty1.types
index f39d98853d2b1..667e51fda8aaa 100644
--- a/tests/baselines/reference/symbolProperty1.types
+++ b/tests/baselines/reference/symbolProperty1.types
@@ -3,8 +3,8 @@ var s: symbol;
 >s : symbol
 
 var x = {
->x : {}
->{    [s]: 0,    [s]() { },    get [s]() {        return 0;    }} : {}
+>x : { [x: string]: number | (() => void); }
+>{    [s]: 0,    [s]() { },    get [s]() {        return 0;    }} : { [x: string]: number | (() => void); }
 
     [s]: 0,
 >s : symbol
diff --git a/tests/baselines/reference/symbolProperty2.types b/tests/baselines/reference/symbolProperty2.types
index df49130520a2e..7584c6461e8ec 100644
--- a/tests/baselines/reference/symbolProperty2.types
+++ b/tests/baselines/reference/symbolProperty2.types
@@ -5,8 +5,8 @@ var s = Symbol();
 >Symbol : SymbolConstructor
 
 var x = {
->x : {}
->{    [s]: 0,    [s]() { },    get [s]() {        return 0;    }} : {}
+>x : { [x: string]: number | (() => void); }
+>{    [s]: 0,    [s]() { },    get [s]() {        return 0;    }} : { [x: string]: number | (() => void); }
 
     [s]: 0,
 >s : symbol
diff --git a/tests/baselines/reference/symbolProperty4.types b/tests/baselines/reference/symbolProperty4.types
index 93b4417b8ae1b..7bcf3f2339769 100644
--- a/tests/baselines/reference/symbolProperty4.types
+++ b/tests/baselines/reference/symbolProperty4.types
@@ -1,7 +1,7 @@
 === tests/cases/conformance/es6/Symbols/symbolProperty4.ts ===
 var x = {
->x : {}
->{    [Symbol()]: 0,    [Symbol()]() { },    get [Symbol()]() {        return 0;    }} : {}
+>x : { [x: string]: number | (() => void); }
+>{    [Symbol()]: 0,    [Symbol()]() { },    get [Symbol()]() {        return 0;    }} : { [x: string]: number | (() => void); }
 
     [Symbol()]: 0,
 >Symbol() : symbol
diff --git a/tests/baselines/reference/templateStringsArrayTypeDefinedInES5Mode.errors.txt b/tests/baselines/reference/templateStringsArrayTypeDefinedInES5Mode.errors.txt
index e6910840d3992..94ab502864775 100644
--- a/tests/baselines/reference/templateStringsArrayTypeDefinedInES5Mode.errors.txt
+++ b/tests/baselines/reference/templateStringsArrayTypeDefinedInES5Mode.errors.txt
@@ -1,5 +1,5 @@
-tests/cases/compiler/templateStringsArrayTypeDefinedInES5Mode.ts(8,3): error TS2345: Argument of type '{ [x: number]: undefined; }' is not assignable to parameter of type 'TemplateStringsArray'.
-  Property 'raw' is missing in type '{ [x: number]: undefined; }'.
+tests/cases/compiler/templateStringsArrayTypeDefinedInES5Mode.ts(8,3): error TS2345: Argument of type '{}' is not assignable to parameter of type 'TemplateStringsArray'.
+  Property 'raw' is missing in type '{}'.
 
 
 ==== tests/cases/compiler/templateStringsArrayTypeDefinedInES5Mode.ts (1 errors) ====
@@ -12,7 +12,7 @@ tests/cases/compiler/templateStringsArrayTypeDefinedInES5Mode.ts(8,3): error TS2
     
     f({}, 10, 10);
       ~~
-!!! error TS2345: Argument of type '{ [x: number]: undefined; }' is not assignable to parameter of type 'TemplateStringsArray'.
-!!! error TS2345:   Property 'raw' is missing in type '{ [x: number]: undefined; }'.
+!!! error TS2345: Argument of type '{}' is not assignable to parameter of type 'TemplateStringsArray'.
+!!! error TS2345:   Property 'raw' is missing in type '{}'.
     
     f `abcdef${ 1234 }${ 5678 }ghijkl`;
\ No newline at end of file
diff --git a/tests/baselines/reference/templateStringsArrayTypeNotDefinedES5Mode.errors.txt b/tests/baselines/reference/templateStringsArrayTypeNotDefinedES5Mode.errors.txt
index e8bf38c104861..1201c82f4d07b 100644
--- a/tests/baselines/reference/templateStringsArrayTypeNotDefinedES5Mode.errors.txt
+++ b/tests/baselines/reference/templateStringsArrayTypeNotDefinedES5Mode.errors.txt
@@ -1,5 +1,5 @@
-tests/cases/compiler/templateStringsArrayTypeNotDefinedES5Mode.ts(5,3): error TS2345: Argument of type '{ [x: number]: undefined; }' is not assignable to parameter of type 'TemplateStringsArray'.
-  Property 'raw' is missing in type '{ [x: number]: undefined; }'.
+tests/cases/compiler/templateStringsArrayTypeNotDefinedES5Mode.ts(5,3): error TS2345: Argument of type '{}' is not assignable to parameter of type 'TemplateStringsArray'.
+  Property 'raw' is missing in type '{}'.
 
 
 ==== tests/cases/compiler/templateStringsArrayTypeNotDefinedES5Mode.ts (1 errors) ====
@@ -9,7 +9,7 @@ tests/cases/compiler/templateStringsArrayTypeNotDefinedES5Mode.ts(5,3): error TS
     
     f({}, 10, 10);
       ~~
-!!! error TS2345: Argument of type '{ [x: number]: undefined; }' is not assignable to parameter of type 'TemplateStringsArray'.
-!!! error TS2345:   Property 'raw' is missing in type '{ [x: number]: undefined; }'.
+!!! error TS2345: Argument of type '{}' is not assignable to parameter of type 'TemplateStringsArray'.
+!!! error TS2345:   Property 'raw' is missing in type '{}'.
     
     f `abcdef${ 1234 }${ 5678 }ghijkl`;
\ No newline at end of file
diff --git a/tests/baselines/reference/templateStringsArrayTypeRedefinedInES6Mode.errors.txt b/tests/baselines/reference/templateStringsArrayTypeRedefinedInES6Mode.errors.txt
index ac30556a23551..f410d40848231 100644
--- a/tests/baselines/reference/templateStringsArrayTypeRedefinedInES6Mode.errors.txt
+++ b/tests/baselines/reference/templateStringsArrayTypeRedefinedInES6Mode.errors.txt
@@ -1,5 +1,5 @@
-tests/cases/compiler/templateStringsArrayTypeRedefinedInES6Mode.ts(8,3): error TS2345: Argument of type '{ [x: number]: undefined; }' is not assignable to parameter of type 'TemplateStringsArray'.
-  Property 'raw' is missing in type '{ [x: number]: undefined; }'.
+tests/cases/compiler/templateStringsArrayTypeRedefinedInES6Mode.ts(8,3): error TS2345: Argument of type '{}' is not assignable to parameter of type 'TemplateStringsArray'.
+  Property 'raw' is missing in type '{}'.
 
 
 ==== tests/cases/compiler/templateStringsArrayTypeRedefinedInES6Mode.ts (1 errors) ====
@@ -12,7 +12,7 @@ tests/cases/compiler/templateStringsArrayTypeRedefinedInES6Mode.ts(8,3): error T
     
     f({}, 10, 10);
       ~~
-!!! error TS2345: Argument of type '{ [x: number]: undefined; }' is not assignable to parameter of type 'TemplateStringsArray'.
-!!! error TS2345:   Property 'raw' is missing in type '{ [x: number]: undefined; }'.
+!!! error TS2345: Argument of type '{}' is not assignable to parameter of type 'TemplateStringsArray'.
+!!! error TS2345:   Property 'raw' is missing in type '{}'.
     
     f `abcdef${ 1234 }${ 5678 }ghijkl`;
\ No newline at end of file
diff --git a/tests/baselines/reference/typeParameterFixingWithConstraints.types b/tests/baselines/reference/typeParameterFixingWithConstraints.types
index 22d294f9d2edb..1e71f439e5e2b 100644
--- a/tests/baselines/reference/typeParameterFixingWithConstraints.types
+++ b/tests/baselines/reference/typeParameterFixingWithConstraints.types
@@ -31,17 +31,17 @@ var foo: IFoo;
 >IFoo : IFoo
 
 foo.foo({ bar: null }, bar => null, bar => null);
->foo.foo({ bar: null }, bar => null, bar => null) : { [x: string]: any; bar: any; }
+>foo.foo({ bar: null }, bar => null, bar => null) : { bar: any; }
 >foo.foo : <TBar extends IBar>(bar: TBar, bar1: (bar: TBar) => TBar, bar2: (bar: TBar) => TBar) => TBar
 >foo : IFoo
 >foo : <TBar extends IBar>(bar: TBar, bar1: (bar: TBar) => TBar, bar2: (bar: TBar) => TBar) => TBar
->{ bar: null } : { [x: string]: null; bar: null; }
+>{ bar: null } : { bar: null; }
 >bar : null
 >null : null
->bar => null : (bar: { [x: string]: any; bar: any; }) => any
->bar : { [x: string]: any; bar: any; }
+>bar => null : (bar: { bar: any; }) => any
+>bar : { bar: any; }
 >null : null
->bar => null : (bar: { [x: string]: any; bar: any; }) => any
->bar : { [x: string]: any; bar: any; }
+>bar => null : (bar: { bar: any; }) => any
+>bar : { bar: any; }
 >null : null
 
diff --git a/tests/baselines/reference/underscoreTest1.types b/tests/baselines/reference/underscoreTest1.types
index 4d8a05a5c381e..37f3bdb12ab13 100644
--- a/tests/baselines/reference/underscoreTest1.types
+++ b/tests/baselines/reference/underscoreTest1.types
@@ -31,7 +31,7 @@ _.each({ one: 1, two: 2, three: 3 }, (value: number, key?: string) => alert(valu
 >_.each : { <T>(list: T[], iterator: Iterator<T, void>, context?: any): void; <T>(list: Dictionary<T>, iterator: Iterator<T, void>, context?: any): void; }
 >_ : Underscore.Static
 >each : { <T>(list: T[], iterator: Iterator<T, void>, context?: any): void; <T>(list: Dictionary<T>, iterator: Iterator<T, void>, context?: any): void; }
->{ one: 1, two: 2, three: 3 } : { [x: string]: number; one: number; two: number; three: number; }
+>{ one: 1, two: 2, three: 3 } : { one: number; two: number; three: number; }
 >one : number
 >1 : number
 >two : number
@@ -68,7 +68,7 @@ _.map({ one: 1, two: 2, three: 3 }, (value: number, key?: string) => value * 3);
 >_.map : { <T, U>(list: T[], iterator: Iterator<T, U>, context?: any): U[]; <T, U>(list: Dictionary<T>, iterator: Iterator<T, U>, context?: any): U[]; }
 >_ : Underscore.Static
 >map : { <T, U>(list: T[], iterator: Iterator<T, U>, context?: any): U[]; <T, U>(list: Dictionary<T>, iterator: Iterator<T, U>, context?: any): U[]; }
->{ one: 1, two: 2, three: 3 } : { [x: string]: number; one: number; two: number; three: number; }
+>{ one: 1, two: 2, three: 3 } : { one: number; two: number; three: number; }
 >one : number
 >1 : number
 >two : number
@@ -449,7 +449,7 @@ _.size({ one: 1, two: 2, three: 3 });
 >_.size : { <T>(list: T[]): number; <T>(list: Dictionary<T>): number; }
 >_ : Underscore.Static
 >size : { <T>(list: T[]): number; <T>(list: Dictionary<T>): number; }
->{ one: 1, two: 2, three: 3 } : { [x: string]: number; one: number; two: number; three: number; }
+>{ one: 1, two: 2, three: 3 } : { one: number; two: number; three: number; }
 >one : number
 >1 : number
 >two : number
diff --git a/tests/baselines/reference/widenedTypes.errors.txt b/tests/baselines/reference/widenedTypes.errors.txt
index 2277ef6eea75a..beda634c2a6da 100644
--- a/tests/baselines/reference/widenedTypes.errors.txt
+++ b/tests/baselines/reference/widenedTypes.errors.txt
@@ -6,8 +6,8 @@ tests/cases/compiler/widenedTypes.ts(11,1): error TS2322: Type 'string' is not a
 tests/cases/compiler/widenedTypes.ts(18,1): error TS2322: Type 'string' is not assignable to type 'number'.
 tests/cases/compiler/widenedTypes.ts(23,5): error TS2322: Type 'number[]' is not assignable to type 'string[]'.
   Type 'number' is not assignable to type 'string'.
-tests/cases/compiler/widenedTypes.ts(24,5): error TS2322: Type '{ [x: string]: number; x: number; y: null; }' is not assignable to type '{ [x: string]: string; }'.
-  Index signatures are incompatible.
+tests/cases/compiler/widenedTypes.ts(24,5): error TS2322: Type '{ x: number; y: null; }' is not assignable to type '{ [x: string]: string; }'.
+  Property 'x' is incompatible with index signature.
     Type 'number' is not assignable to type 'string'.
 
 
@@ -52,6 +52,6 @@ tests/cases/compiler/widenedTypes.ts(24,5): error TS2322: Type '{ [x: string]: n
 !!! error TS2322:   Type 'number' is not assignable to type 'string'.
     var obj: { [x: string]: string; } = { x: 3, y: null }; // assignable because null is widened, and therefore BCT is any
         ~~~
-!!! error TS2322: Type '{ [x: string]: number; x: number; y: null; }' is not assignable to type '{ [x: string]: string; }'.
-!!! error TS2322:   Index signatures are incompatible.
+!!! error TS2322: Type '{ x: number; y: null; }' is not assignable to type '{ [x: string]: string; }'.
+!!! error TS2322:   Property 'x' is incompatible with index signature.
 !!! error TS2322:     Type 'number' is not assignable to type 'string'.
\ No newline at end of file
diff --git a/tests/baselines/reference/wrappedAndRecursiveConstraints4.errors.txt b/tests/baselines/reference/wrappedAndRecursiveConstraints4.errors.txt
index 60602351b465c..47e8e6ff4f295 100644
--- a/tests/baselines/reference/wrappedAndRecursiveConstraints4.errors.txt
+++ b/tests/baselines/reference/wrappedAndRecursiveConstraints4.errors.txt
@@ -1,4 +1,4 @@
-tests/cases/conformance/types/typeParameters/typeArgumentLists/wrappedAndRecursiveConstraints4.ts(13,12): error TS2345: Argument of type '{ [x: number]: undefined; length: number; charAt: (x: number) => void; }' is not assignable to parameter of type 'string'.
+tests/cases/conformance/types/typeParameters/typeArgumentLists/wrappedAndRecursiveConstraints4.ts(13,12): error TS2345: Argument of type '{ length: number; charAt: (x: number) => void; }' is not assignable to parameter of type 'string'.
 
 
 ==== tests/cases/conformance/types/typeParameters/typeArgumentLists/wrappedAndRecursiveConstraints4.ts (1 errors) ====
@@ -16,4 +16,4 @@ tests/cases/conformance/types/typeParameters/typeArgumentLists/wrappedAndRecursi
     var r = c.foo('');
     var r2 = r({ length: 3, charAt: (x: number) => { '' } }); // error
                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2345: Argument of type '{ [x: number]: undefined; length: number; charAt: (x: number) => void; }' is not assignable to parameter of type 'string'.
\ No newline at end of file
+!!! error TS2345: Argument of type '{ length: number; charAt: (x: number) => void; }' is not assignable to parameter of type 'string'.
\ No newline at end of file
diff --git a/tests/cases/compiler/implicitIndexSignatures.ts b/tests/cases/compiler/implicitIndexSignatures.ts
new file mode 100644
index 0000000000000..2e36a91badab3
--- /dev/null
+++ b/tests/cases/compiler/implicitIndexSignatures.ts
@@ -0,0 +1,45 @@
+type StringMap = { [x: string]: string };
+
+const empty1 = {};
+let empty2: {};
+const names1 = { a: "foo", b: "bar" };
+let names2: { a: string, b: string };
+let map: StringMap;
+map = { x: "xxx", y: "yyy" };
+map = empty1;
+map = empty2;
+map = names1;
+map = names2;
+
+declare function getStringIndexValue<T>(map: { [x: string]: T }): T;
+declare function getNumberIndexValue<T>(map: { [x: number]: T }): T;
+
+function f1() {
+    const o1 = { a: 1, b: 2 };
+    let o2: { a: number, b: number };
+    const v1 = getStringIndexValue(o1);
+    const v2 = getStringIndexValue(o2);
+}
+
+function f2() {
+    const o1 = { a: "1", b: "2" };
+    let o2: { a: string, b: string };
+    const v1 = getStringIndexValue(o1);
+    const v2 = getStringIndexValue(o2);
+}
+
+function f3() {
+    const o1 = { a: 1, b: "2" };
+    let o2: { a: number, b: string };
+    const v1 = getStringIndexValue(o1);
+    const v2 = getStringIndexValue(o2);
+}
+
+function f4() {
+    const o1 = { 0: "0", 1: "1", count: 2 };
+    let o2: { 0: string, 1: string, count: number };    
+    const v1 = getStringIndexValue(o1);
+    const v2 = getStringIndexValue(o2);
+    const v3 = getNumberIndexValue(o1);
+    const v4 = getNumberIndexValue(o2);
+}

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