Merge pull request #18207 from Microsoft/recursive-type-reference-cache

Expand type references recursively in cache key

Author: sandersn

src/compiler/checker.ts

@@ -9781,15 +9781,15 @@ namespace ts {
             return type.flags & TypeFlags.TypeParameter && !getConstraintFromTypeParameter(<TypeParameter>type);
         }
 
-        function isTypeReferenceWithGenericArguments(type: Type) {
-            return getObjectFlags(type) & ObjectFlags.Reference && some((<TypeReference>type).typeArguments, isUnconstrainedTypeParameter);
+        function isTypeReferenceWithGenericArguments(type: Type): boolean {
+            return getObjectFlags(type) & ObjectFlags.Reference && some((<TypeReference>type).typeArguments, t => isUnconstrainedTypeParameter(t) || isTypeReferenceWithGenericArguments(t));
         }
 
         /**
          * getTypeReferenceId(A<T, number, U>) returns "111=0-12=1"
          *   where A.id=111 and number.id=12
          */
-        function getTypeReferenceId(type: TypeReference, typeParameters: Type[]) {
+        function getTypeReferenceId(type: TypeReference, typeParameters: Type[], depth = 0) {
             let result = "" + type.target.id;
             for (const t of type.typeArguments) {
                 if (isUnconstrainedTypeParameter(t)) {
@@ -9800,6 +9800,9 @@ namespace ts {
                     }
                     result += "=" + index;
                 }
+                else if (depth < 4 && isTypeReferenceWithGenericArguments(t)) {
+                    result += "<" + getTypeReferenceId(t as TypeReference, typeParameters, depth + 1) + ">";
+                }
                 else {
                     result += "-" + t.id;
                 }