Fixed a symbol display crash on expando members write locations (#55478)

Andarist · web-flow · commit 89c572ca0cbe · 2025-04-01T13:40:59.000-07:00
diff --git a/src/services/symbolDisplay.ts b/src/services/symbolDisplay.ts
@@ -1,4 +1,5 @@
 import {
+    AccessorDeclaration,
     addRange,
     arrayFrom,
     BinaryExpression,
@@ -16,7 +17,6 @@ import {
     first,
     firstDefined,
     forEach,
-    GetAccessorDeclaration,
     getCombinedLocalAndExportSymbolFlags,
     getDeclarationOfKind,
     getExternalModuleImportEqualsDeclarationExpression,
@@ -83,7 +83,6 @@ import {
     ScriptElementKind,
     ScriptElementKindModifier,
     SemanticMeaning,
-    SetAccessorDeclaration,
     Signature,
     SignatureDeclaration,
     SignatureFlags,
@@ -276,7 +275,14 @@ function getSymbolDisplayPartsDocumentationAndSymbolKindWorker(typeChecker: Type
     if (symbolKind !== ScriptElementKind.unknown || symbolFlags & SymbolFlags.Class || symbolFlags & SymbolFlags.Alias) {
         // If symbol is accessor, they are allowed only if location is at declaration identifier of the accessor
         if (symbolKind === ScriptElementKind.memberGetAccessorElement || symbolKind === ScriptElementKind.memberSetAccessorElement) {
-            const declaration = find(symbol.declarations as ((GetAccessorDeclaration | SetAccessorDeclaration | PropertyDeclaration)[]), declaration => declaration.name === location);
+            const declaration = find(
+                symbol.declarations as (AccessorDeclaration | PropertyDeclaration | PropertyAccessExpression)[],
+                (declaration): declaration is AccessorDeclaration | PropertyDeclaration =>
+                    declaration.name === location
+                    // an expando member could have been added to an object with a set accessor
+                    // we need to ignore such write location as it shouldn't be displayed as `(setter)` anyway
+                    && declaration.kind !== SyntaxKind.PropertyAccessExpression,
+            );
             if (declaration) {
                 switch (declaration.kind) {
                     case SyntaxKind.GetAccessor:
diff --git a/tests/cases/fourslash/quickInfoOnExpandoLikePropertyWithSetterDeclarationJs1.ts b/tests/cases/fourslash/quickInfoOnExpandoLikePropertyWithSetterDeclarationJs1.ts
@@ -0,0 +1,16 @@
+/// <reference path="fourslash.ts" />
+
+// @strict: true
+// @checkJs: true
+// @filename: index.js
+
+//// const x = {};
+////
+//// Object.defineProperty(x, "foo", {
+////   /** @param {number} v */
+////   set(v) {},
+//// });
+////
+//// x.foo/**/ = 1;
+
+verify.quickInfoAt("", "(property) x.foo: number");
diff --git a/tests/cases/fourslash/quickInfoOnExpandoLikePropertyWithSetterDeclarationJs2.ts b/tests/cases/fourslash/quickInfoOnExpandoLikePropertyWithSetterDeclarationJs2.ts
@@ -0,0 +1,19 @@
+/// <reference path="fourslash.ts" />
+
+// @strict: true
+// @checkJs: true
+// @filename: index.js
+
+//// const obj = {};
+//// let val = 10;
+//// Object.defineProperty(obj, "a", {
+////   configurable: true,
+////   enumerable: true,
+////   set(v) {
+////     val = v;
+////   },
+//// });
+////
+//// obj.a/**/ = 100;
+
+verify.quickInfoAt("", "(property) obj.a: any");
