Provide type-only completions at default type argument positions (#56534)

Author: Andarist

src/services/completions.ts

@@ -3943,7 +3943,7 @@ function getCompletionData(
                         isFunctionLikeKind(parentKind);
 
                 case SyntaxKind.EqualsToken:
-                    return parentKind === SyntaxKind.TypeAliasDeclaration;
+                    return parentKind === SyntaxKind.TypeAliasDeclaration || parentKind === SyntaxKind.TypeParameter;
 
                 case SyntaxKind.AsKeyword:
                     return parentKind === SyntaxKind.AsExpression;

tests/cases/fourslash/completionListDefaultTypeArgumentPositionTypeOnly.ts

@@ -0,0 +1,6 @@
+/// <reference path='fourslash.ts'/>
+
+//// const foo = "foo";
+//// function test1<T = /*1*/>() {}
+
+verify.completions({ marker: "1", exact: completion.globalTypes });

tests/cases/fourslash/completionListIsGlobalCompletion.ts

@@ -48,7 +48,7 @@ verify.completions(
     { marker: "7", exact: completion.globalsInsideFunction(x), isGlobalCompletion: true },
     { marker: "9", exact: ["x", "y"], isGlobalCompletion: false },
     { marker: "10", exact: completion.classElementKeywords, isGlobalCompletion: false, isNewIdentifierLocation: true },
-    { marker: "13", exact: globals, isGlobalCompletion: false },
+    { marker: "13", exact: completion.globalTypesPlus(["A", "B", "C"]), isGlobalCompletion: false },
     { marker: "15", exact: globals.filter(name => name !== 'x'), isGlobalCompletion: true, isNewIdentifierLocation: true },
     { marker: "16", unsorted: [...x, completion.globalThisEntry, ...completion.globalsVars, completion.undefinedVarEntry].filter(name => name !== 'user'), isGlobalCompletion: false },
     { marker: "17", exact: completion.globalKeywords, isGlobalCompletion: false },