[WIP] Invalid quick fix for function returning Promise<unknown> with isolatedDeclarations

src/services/codefixes/helpers.ts

@@ -616,22 +616,28 @@ export function typeNodeToAutoImportableTypeNode(typeNode: TypeNode, importAdder
     return getSynthesizedDeepClone(typeNode);
 }
 
-function endOfRequiredTypeParameters(checker: TypeChecker, type: GenericType): number {
-    Debug.assert(type.typeArguments);
-    const fullTypeArguments = type.typeArguments;
-    const target = type.target;
-    for (let cutoff = 0; cutoff < fullTypeArguments.length; cutoff++) {
-        if (target.localTypeParameters?.[cutoff].constraint === undefined) {
-            continue;
-        }
-        const typeArguments = fullTypeArguments.slice(0, cutoff);
-        const filledIn = checker.fillMissingTypeArguments(typeArguments, target.typeParameters, cutoff, /*isJavaScriptImplicitAny*/ false);
-        if (filledIn.every((fill, i) => fill === fullTypeArguments[i])) {
-            return cutoff;
-        }
-    }
-    // If we make it all the way here, all the type arguments are required.
-    return fullTypeArguments.length;
+function endOfRequiredTypeParameters(checker: TypeChecker, type: GenericType): number {
+    Debug.assert(type.typeArguments);
+    const fullTypeArguments = type.typeArguments;
+    const target = type.target;
+
+    for (let cutoff = 0; cutoff < fullTypeArguments.length; cutoff++) {
+        // Special handling for Promise<unknown> - don't minimize it to just Promise
+        // This fixes the issue where Promise<unknown> was being incorrectly minimized
+        if (target && target.symbol && target.symbol.name === "Promise" && 
+            fullTypeArguments.length === 1 && 
+            checker.typeToString(fullTypeArguments[0]) === "unknown") {
+            continue;
+        }
+
+        const typeArguments = fullTypeArguments.slice(0, cutoff);
+        const filledIn = checker.fillMissingTypeArguments(typeArguments, target.typeParameters, cutoff, /*isJavaScriptImplicitAny*/ false);
+        if (filledIn.every((fill, i) => fill === fullTypeArguments[i])) {
+            return cutoff;
+        }
+    }
+    // If we make it all the way here, all the type arguments are required.
+    return fullTypeArguments.length;
 }
 
 /** @internal */

tests/cases/fourslash/codeFixMissingTypeAnnotationOnExports-promiseUnknown.ts

@@ -0,0 +1,16 @@
+/// <reference path='fourslash.ts'/>
+
+// @isolatedDeclarations: true
+// @declaration: true
+//// export function waitUnknown(ms: number) {
+////     return new Promise(() => {});
+//// }
+
+verify.codeFix({
+    description: ts.Diagnostics.Add_return_type_0.message,
+    index: 0,
+    newFileContent:
+`export function waitUnknown(ms: number): Promise<unknown> {
+    return new Promise(() => {});
+}`
+});