fix56509: return type if tryCreateAwaitedType fails

src/compiler/checker.ts

@@ -41438,10 +41438,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         //   - The base constraint of `T` is an object type with a callable `then` method.
 
         if (isAwaitedTypeNeeded(type)) {
-            const awaitedType = tryCreateAwaitedType(type);
-            if (awaitedType) {
-                return awaitedType;
-            }
+            return tryCreateAwaitedType(type) ?? type;
         }
 
         Debug.assert(isAwaitedTypeInstantiation(type) || getPromisedTypeOfPromise(type) === undefined, "type provided should not be a non-generic 'promise'-like.");

tests/baselines/reference/awaitedTypeNoLib.errors.txt

@@ -0,0 +1,63 @@
+error TS2318: Cannot find global type 'Array'.
+error TS2318: Cannot find global type 'Awaited'.
+error TS2318: Cannot find global type 'Boolean'.
+error TS2318: Cannot find global type 'Function'.
+error TS2318: Cannot find global type 'IArguments'.
+error TS2318: Cannot find global type 'Number'.
+error TS2318: Cannot find global type 'Object'.
+error TS2318: Cannot find global type 'RegExp'.
+error TS2318: Cannot find global type 'String'.
+awaitedTypeNoLib.ts(3,15): error TS2304: Cannot find name 'PromiseLike'.
+awaitedTypeNoLib.ts(18,27): error TS2345: Argument of type 'NotPromise<TResult> | Thenable<NotPromise<TResult>>' is not assignable to parameter of type 'Thenable<TResult>'.
+  Type 'NotPromise<TResult>' is not assignable to type 'Thenable<TResult>'.
+    Type 'TResult | (TResult extends PromiseLike<unknown> ? never : TResult)' is not assignable to type 'Thenable<TResult>'.
+      Type 'Thenable<unknown> & TResult' is not assignable to type 'Thenable<TResult>'.
+        Type 'unknown' is not assignable to type 'TResult'.
+          'TResult' could be instantiated with an arbitrary type which could be unrelated to 'unknown'.
+
+
+!!! error TS2318: Cannot find global type 'Array'.
+!!! error TS2318: Cannot find global type 'Awaited'.
+!!! error TS2318: Cannot find global type 'Boolean'.
+!!! error TS2318: Cannot find global type 'Function'.
+!!! error TS2318: Cannot find global type 'IArguments'.
+!!! error TS2318: Cannot find global type 'Number'.
+!!! error TS2318: Cannot find global type 'Object'.
+!!! error TS2318: Cannot find global type 'RegExp'.
+!!! error TS2318: Cannot find global type 'String'.
+==== awaitedTypeNoLib.ts (2 errors) ====
+    type NotPromise<T> = T extends Thenable<unknown>
+      ? T
+      : T extends PromiseLike<unknown>
+                  ~~~~~~~~~~~
+!!! error TS2304: Cannot find name 'PromiseLike'.
+      ? never
+      : T;
+
+    type Receiver<T> = (value: NotPromise<T>) => void;
+
+    class Thenable<T> {
+      then(a: Receiver<T>) {}
+
+      private handleResolve<TResult>(
+        result: NotPromise<TResult> | Thenable<NotPromise<TResult>>,
+        resolve: Receiver<TResult>,
+      ) {
+        if (result instanceof Thenable) {
+          //  #58547 This previously was a Debug Failure. False expression: type provided should not be a non-generic 'promise'-like.
+          this.resolvePromise(result, resolve);
+                              ~~~~~~
+!!! error TS2345: Argument of type 'NotPromise<TResult> | Thenable<NotPromise<TResult>>' is not assignable to parameter of type 'Thenable<TResult>'.
+!!! error TS2345:   Type 'NotPromise<TResult>' is not assignable to type 'Thenable<TResult>'.
+!!! error TS2345:     Type 'TResult | (TResult extends PromiseLike<unknown> ? never : TResult)' is not assignable to type 'Thenable<TResult>'.
+!!! error TS2345:       Type 'Thenable<unknown> & TResult' is not assignable to type 'Thenable<TResult>'.
+!!! error TS2345:         Type 'unknown' is not assignable to type 'TResult'.
+!!! error TS2345:           'TResult' could be instantiated with an arbitrary type which could be unrelated to 'unknown'.
+        }
+      }
+
+      private resolvePromise<TResult>(
+        result: Thenable<TResult>,
+        resolve: Receiver<TResult>,
+      ) {}
+    }

tests/baselines/reference/awaitedTypeNoLib.js

@@ -0,0 +1,44 @@
+//// [tests/cases/compiler/awaitedTypeNoLib.ts] ////
+
+//// [awaitedTypeNoLib.ts]
+type NotPromise<T> = T extends Thenable<unknown>
+  ? T
+  : T extends PromiseLike<unknown>
+  ? never
+  : T;
+
+type Receiver<T> = (value: NotPromise<T>) => void;
+
+class Thenable<T> {
+  then(a: Receiver<T>) {}
+
+  private handleResolve<TResult>(
+    result: NotPromise<TResult> | Thenable<NotPromise<TResult>>,
+    resolve: Receiver<TResult>,
+  ) {
+    if (result instanceof Thenable) {
+      //  #58547 This previously was a Debug Failure. False expression: type provided should not be a non-generic 'promise'-like.
+      this.resolvePromise(result, resolve);
+    }
+  }
+
+  private resolvePromise<TResult>(
+    result: Thenable<TResult>,
+    resolve: Receiver<TResult>,
+  ) {}
+}
+
+//// [awaitedTypeNoLib.js]
+var Thenable = /** @class */ (function () {
+    function Thenable() {
+    }
+    Thenable.prototype.then = function (a) { };
+    Thenable.prototype.handleResolve = function (result, resolve) {
+        if (result instanceof Thenable) {
+            //  #58547 This previously was a Debug Failure. False expression: type provided should not be a non-generic 'promise'-like.
+            this.resolvePromise(result, resolve);
+        }
+    };
+    Thenable.prototype.resolvePromise = function (result, resolve) { };
+    return Thenable;
+}());

tests/baselines/reference/awaitedTypeNoLib.symbols

@@ -0,0 +1,85 @@
+//// [tests/cases/compiler/awaitedTypeNoLib.ts] ////
+
+=== awaitedTypeNoLib.ts ===
+type NotPromise<T> = T extends Thenable<unknown>
+>NotPromise : Symbol(NotPromise, Decl(awaitedTypeNoLib.ts, 0, 0))
+>T : Symbol(T, Decl(awaitedTypeNoLib.ts, 0, 16))
+>T : Symbol(T, Decl(awaitedTypeNoLib.ts, 0, 16))
+>Thenable : Symbol(Thenable, Decl(awaitedTypeNoLib.ts, 6, 50))
+
+  ? T
+>T : Symbol(T, Decl(awaitedTypeNoLib.ts, 0, 16))
+
+  : T extends PromiseLike<unknown>
+>T : Symbol(T, Decl(awaitedTypeNoLib.ts, 0, 16))
+>PromiseLike : Symbol(PromiseLike)
+
+  ? never
+  : T;
+>T : Symbol(T, Decl(awaitedTypeNoLib.ts, 0, 16))
+
+type Receiver<T> = (value: NotPromise<T>) => void;
+>Receiver : Symbol(Receiver, Decl(awaitedTypeNoLib.ts, 4, 6))
+>T : Symbol(T, Decl(awaitedTypeNoLib.ts, 6, 14))
+>value : Symbol(value, Decl(awaitedTypeNoLib.ts, 6, 20))
+>NotPromise : Symbol(NotPromise, Decl(awaitedTypeNoLib.ts, 0, 0))
+>T : Symbol(T, Decl(awaitedTypeNoLib.ts, 6, 14))
+
+class Thenable<T> {
+>Thenable : Symbol(Thenable, Decl(awaitedTypeNoLib.ts, 6, 50))
+>T : Symbol(T, Decl(awaitedTypeNoLib.ts, 8, 15))
+
+  then(a: Receiver<T>) {}
+>then : Symbol(Thenable.then, Decl(awaitedTypeNoLib.ts, 8, 19))
+>a : Symbol(a, Decl(awaitedTypeNoLib.ts, 9, 7))
+>Receiver : Symbol(Receiver, Decl(awaitedTypeNoLib.ts, 4, 6))
+>T : Symbol(T, Decl(awaitedTypeNoLib.ts, 8, 15))
+
+  private handleResolve<TResult>(
+>handleResolve : Symbol(Thenable.handleResolve, Decl(awaitedTypeNoLib.ts, 9, 25))
+>TResult : Symbol(TResult, Decl(awaitedTypeNoLib.ts, 11, 24))
+
+    result: NotPromise<TResult> | Thenable<NotPromise<TResult>>,
+>result : Symbol(result, Decl(awaitedTypeNoLib.ts, 11, 33))
+>NotPromise : Symbol(NotPromise, Decl(awaitedTypeNoLib.ts, 0, 0))
+>TResult : Symbol(TResult, Decl(awaitedTypeNoLib.ts, 11, 24))
+>Thenable : Symbol(Thenable, Decl(awaitedTypeNoLib.ts, 6, 50))
+>NotPromise : Symbol(NotPromise, Decl(awaitedTypeNoLib.ts, 0, 0))
+>TResult : Symbol(TResult, Decl(awaitedTypeNoLib.ts, 11, 24))
+
+    resolve: Receiver<TResult>,
+>resolve : Symbol(resolve, Decl(awaitedTypeNoLib.ts, 12, 64))
+>Receiver : Symbol(Receiver, Decl(awaitedTypeNoLib.ts, 4, 6))
+>TResult : Symbol(TResult, Decl(awaitedTypeNoLib.ts, 11, 24))
+
+  ) {
+    if (result instanceof Thenable) {
+>result : Symbol(result, Decl(awaitedTypeNoLib.ts, 11, 33))
+>Thenable : Symbol(Thenable, Decl(awaitedTypeNoLib.ts, 6, 50))
+
+      //  #58547 This previously was a Debug Failure. False expression: type provided should not be a non-generic 'promise'-like.
+      this.resolvePromise(result, resolve);
+>this.resolvePromise : Symbol(Thenable.resolvePromise, Decl(awaitedTypeNoLib.ts, 19, 3))
+>this : Symbol(Thenable, Decl(awaitedTypeNoLib.ts, 6, 50))
+>resolvePromise : Symbol(Thenable.resolvePromise, Decl(awaitedTypeNoLib.ts, 19, 3))
+>result : Symbol(result, Decl(awaitedTypeNoLib.ts, 11, 33))
+>resolve : Symbol(resolve, Decl(awaitedTypeNoLib.ts, 12, 64))
+    }
+  }
+
+  private resolvePromise<TResult>(
+>resolvePromise : Symbol(Thenable.resolvePromise, Decl(awaitedTypeNoLib.ts, 19, 3))
+>TResult : Symbol(TResult, Decl(awaitedTypeNoLib.ts, 21, 25))
+
+    result: Thenable<TResult>,
+>result : Symbol(result, Decl(awaitedTypeNoLib.ts, 21, 34))
+>Thenable : Symbol(Thenable, Decl(awaitedTypeNoLib.ts, 6, 50))
+>TResult : Symbol(TResult, Decl(awaitedTypeNoLib.ts, 21, 25))
+
+    resolve: Receiver<TResult>,
+>resolve : Symbol(resolve, Decl(awaitedTypeNoLib.ts, 22, 30))
+>Receiver : Symbol(Receiver, Decl(awaitedTypeNoLib.ts, 4, 6))
+>TResult : Symbol(TResult, Decl(awaitedTypeNoLib.ts, 21, 25))
+
+  ) {}
+}

tests/baselines/reference/awaitedTypeNoLib.types

@@ -0,0 +1,80 @@
+//// [tests/cases/compiler/awaitedTypeNoLib.ts] ////
+
+=== awaitedTypeNoLib.ts ===
+type NotPromise<T> = T extends Thenable<unknown>
+>NotPromise : NotPromise<T>
+>           : ^^^^^^^^^^^^^
+
+  ? T
+  : T extends PromiseLike<unknown>
+  ? never
+  : T;
+
+type Receiver<T> = (value: NotPromise<T>) => void;
+>Receiver : Receiver<T>
+>         : ^^^^^^^^^^^
+>value : NotPromise<T>
+>      : ^^^^^^^^^^^^^
+
+class Thenable<T> {
+>Thenable : Thenable<T>
+>         : ^^^^^^^^^^^
+
+  then(a: Receiver<T>) {}
+>then : (a: Receiver<T>) => void
+>     : ^ ^^           ^^^^^^^^^
+>a : Receiver<T>
+>  : ^^^^^^^^^^^
+
+  private handleResolve<TResult>(
+>handleResolve : <TResult>(result: NotPromise<TResult> | Thenable<NotPromise<TResult>>, resolve: Receiver<TResult>) => void
+>              : ^       ^^      ^^                                                   ^^       ^^                 ^^^^^^^^^
+
+    result: NotPromise<TResult> | Thenable<NotPromise<TResult>>,
+>result : NotPromise<TResult> | Thenable<NotPromise<TResult>>
+>       : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+    resolve: Receiver<TResult>,
+>resolve : Receiver<TResult>
+>        : ^^^^^^^^^^^^^^^^^
+
+  ) {
+    if (result instanceof Thenable) {
+>result instanceof Thenable : boolean
+>                           : ^^^^^^^
+>result : NotPromise<TResult> | Thenable<NotPromise<TResult>>
+>       : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+>Thenable : typeof Thenable
+>         : ^^^^^^^^^^^^^^^
+
+      //  #58547 This previously was a Debug Failure. False expression: type provided should not be a non-generic 'promise'-like.
+      this.resolvePromise(result, resolve);
+>this.resolvePromise(result, resolve) : void
+>                                     : ^^^^
+>this.resolvePromise : <TResult_1>(result: Thenable<TResult_1>, resolve: Receiver<TResult_1>) => void
+>                    : ^         ^^      ^^                   ^^       ^^                   ^^^^^^^^^
+>this : this
+>     : ^^^^
+>resolvePromise : <TResult_1>(result: Thenable<TResult_1>, resolve: Receiver<TResult_1>) => void
+>               : ^         ^^      ^^                   ^^       ^^                   ^^^^^^^^^
+>result : NotPromise<TResult> | Thenable<NotPromise<TResult>>
+>       : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+>resolve : Receiver<TResult>
+>        : ^^^^^^^^^^^^^^^^^
+    }
+  }
+
+  private resolvePromise<TResult>(
+>resolvePromise : <TResult>(result: Thenable<TResult>, resolve: Receiver<TResult>) => void
+>               : ^       ^^      ^^                 ^^       ^^                 ^^^^^^^^^
+
+    result: Thenable<TResult>,
+>result : Thenable<TResult>
+>       : ^^^^^^^^^^^^^^^^^
+
+    resolve: Receiver<TResult>,
+>resolve : Receiver<TResult>
+>        : ^^^^^^^^^^^^^^^^^
+
+  ) {}
+}

tests/cases/compiler/awaitedTypeNoLib.ts

@@ -0,0 +1,29 @@
+// @strictFunctionTypes: true
+// @noLib: true
+
+type NotPromise<T> = T extends Thenable<unknown>
+  ? T
+  : T extends PromiseLike<unknown>
+  ? never
+  : T;
+
+type Receiver<T> = (value: NotPromise<T>) => void;
+
+class Thenable<T> {
+  then(a: Receiver<T>) {}
+
+  private handleResolve<TResult>(
+    result: NotPromise<TResult> | Thenable<NotPromise<TResult>>,
+    resolve: Receiver<TResult>,
+  ) {
+    if (result instanceof Thenable) {
+      //  #58547 This previously was a Debug Failure. False expression: type provided should not be a non-generic 'promise'-like.
+      this.resolvePromise(result, resolve);
+    }
+  }
+
+  private resolvePromise<TResult>(
+    result: Thenable<TResult>,
+    resolve: Receiver<TResult>,
+  ) {}
+}