handle type aliases higher up

danvk · danvk · commit bacd28d06952 · 2024-08-19T11:49:02.000-04:00
diff --git a/packages/eslint-plugin/src/rules/no-unnecessary-type-parameters.ts b/packages/eslint-plugin/src/rules/no-unnecessary-type-parameters.ts
@@ -258,6 +258,13 @@ function collectTypeParameterUsageCounts(
       }
     }
 
+    // Catch-all: generic type references like `Exclude<T, null>`
+    else if (type.aliasTypeArguments) {
+      // We don't descend into the definition of the type alias, so we don't
+      // know whether it's used multiple times. It's safest to assume it is.
+      visitTypesList(type.aliasTypeArguments, true);
+    }
+
     // Intersections and unions like `0 | 1`
     else if (tsutils.isUnionOrIntersectionType(type)) {
       visitTypesList(type.types, assumeMultipleUses);
@@ -288,9 +295,6 @@ function collectTypeParameterUsageCounts(
     else if (tsutils.isConditionalType(type)) {
       visitType(type.checkType, assumeMultipleUses);
       visitType(type.extendsType, assumeMultipleUses);
-      type.aliasTypeArguments?.forEach(typeArgument =>
-        visitType(typeArgument, false),
-      );
     }
 
     // Catch-all: inferred object types like `{ K: V }`.
@@ -310,10 +314,6 @@ function collectTypeParameterUsageCounts(
         }
       }
 
-      for (const typeArgument of type.aliasTypeArguments ?? []) {
-        visitType(typeArgument, true);
-      }
-
       visitType(type.getNumberIndexType(), true);
       visitType(type.getStringIndexType(), true);
 
@@ -332,11 +332,6 @@ function collectTypeParameterUsageCounts(
     else if (isOperatorType(type)) {
       visitType(type.type, assumeMultipleUses);
     }
-
-    // Catch-all: generic type references like `Exclude<T, null>`
-    else if (type.aliasTypeArguments) {
-      visitTypesList(type.aliasTypeArguments, true);
-    }
   }
 
   function incrementIdentifierCount(

Original file line number	Diff line number	Diff line change
`@@ -258,6 +258,13 @@ function collectTypeParameterUsageCounts(`
`258`	`258`	`}`
`259`	`259`	`}`
`260`	`260`
	`261`	+ // Catch-all: generic type references like `Exclude<T, null>`
	`262`	`+ else if (type.aliasTypeArguments) {`
	`263`	`+ // We don't descend into the definition of the type alias, so we don't`
	`264`	`+ // know whether it's used multiple times. It's safest to assume it is.`
	`265`	`+ visitTypesList(type.aliasTypeArguments, true);`
	`266`	`+ }`
	`267`	`+`
`261`	`268`	// Intersections and unions like `0 \| 1`
`262`	`269`	`else if (tsutils.isUnionOrIntersectionType(type)) {`
`263`	`270`	`visitTypesList(type.types, assumeMultipleUses);`
`@@ -288,9 +295,6 @@ function collectTypeParameterUsageCounts(`
`288`	`295`	`else if (tsutils.isConditionalType(type)) {`
`289`	`296`	`visitType(type.checkType, assumeMultipleUses);`
`290`	`297`	`visitType(type.extendsType, assumeMultipleUses);`
`291`		`- type.aliasTypeArguments?.forEach(typeArgument =>`
`292`		`- visitType(typeArgument, false),`
`293`		`- );`
`294`	`298`	`}`
`295`	`299`
`296`	`300`	// Catch-all: inferred object types like `{ K: V }`.
`@@ -310,10 +314,6 @@ function collectTypeParameterUsageCounts(`
`310`	`314`	`}`
`311`	`315`	`}`
`312`	`316`
`313`		`- for (const typeArgument of type.aliasTypeArguments ?? []) {`
`314`		`- visitType(typeArgument, true);`
`315`		`- }`
`316`		`-`
`317`	`317`	`visitType(type.getNumberIndexType(), true);`
`318`	`318`	`visitType(type.getStringIndexType(), true);`
`319`	`319`
`@@ -332,11 +332,6 @@ function collectTypeParameterUsageCounts(`
`332`	`332`	`else if (isOperatorType(type)) {`
`333`	`333`	`visitType(type.type, assumeMultipleUses);`
`334`	`334`	`}`
`335`		`-`
`336`		- // Catch-all: generic type references like `Exclude<T, null>`
`337`		`- else if (type.aliasTypeArguments) {`
`338`		`- visitTypesList(type.aliasTypeArguments, true);`
`339`		`- }`
`340`	`335`	`}`
`341`	`336`
`342`	`337`	`function incrementIdentifierCount(`