Revert microsoft#54477 but keep the tests

Discovered in microsoft#57117

The implementation should not `couldContainTypeVariables`--it's not
intended a fast path, and should not be used in places where its
unreliability can be observed.

The tests stay, but with a note added that they should pass but do not.

src/compiler/checker.ts

@@ -39347,20 +39347,17 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         }
     }
 
-    function getNonGenericReturnTypeOfSingleCallSignature(funcType: Type) {
+    function getReturnTypeOfSingleNonGenericCallSignature(funcType: Type) {
         const signature = getSingleCallSignature(funcType);
-        if (signature) {
-            const returnType = getReturnTypeOfSignature(signature);
-            if (!signature.typeParameters || !couldContainTypeVariables(returnType)) {
-                return returnType;
-            }
+        if (signature && !signature.typeParameters) {
+            return getReturnTypeOfSignature(signature);
         }
     }
 
     function getReturnTypeOfSingleNonGenericSignatureOfCallChain(expr: CallChain) {
         const funcType = checkExpression(expr.expression);
         const nonOptionalType = getOptionalExpressionType(funcType, expr.expression);
-        const returnType = getNonGenericReturnTypeOfSingleCallSignature(funcType);
+        const returnType = getReturnTypeOfSingleNonGenericCallSignature(funcType);
         return returnType && propagateOptionalTypeMarker(returnType, expr, nonOptionalType !== funcType);
     }
 
@@ -39409,7 +39406,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         // signature where we can just fetch the return type without checking the arguments.
         if (isCallExpression(expr) && expr.expression.kind !== SyntaxKind.SuperKeyword && !isRequireCall(expr, /*requireStringLiteralLikeArgument*/ true) && !isSymbolOrSymbolForCall(expr)) {
             return isCallChain(expr) ? getReturnTypeOfSingleNonGenericSignatureOfCallChain(expr) :
-                getNonGenericReturnTypeOfSingleCallSignature(checkNonNullExpression(expr.expression));
+                getReturnTypeOfSingleNonGenericCallSignature(checkNonNullExpression(expr.expression));
         }
         else if (isAssertionExpression(expr) && !isConstTypeReference(expr.type)) {
             return getTypeFromTypeNode((expr as TypeAssertion).type);

tests/baselines/reference/arrayFrom.types

@@ -31,7 +31,7 @@ const inputALike: ArrayLike<A> = { length: 0 };
 const inputARand = getEither(inputA, inputALike);
 >inputARand : ArrayLike<A> | Iterable<A>
 >getEither(inputA, inputALike) : ArrayLike<A> | Iterable<A>
->getEither : <T>(in1: Iterable<T>, in2: ArrayLike<T>) => Iterable<T> | ArrayLike<T>
+>getEither : <T>(in1: Iterable<T>, in2: ArrayLike<T>) => ArrayLike<T> | Iterable<T>
 >inputA : A[]
 >inputALike : ArrayLike<A>
 
@@ -163,12 +163,12 @@ const result11: B[] = Array.from(inputASet, ({ a }): B => ({ b: a }));
 // the ?: as always taking the false branch, narrowing to ArrayLike<T>,
 // even when the type is written as : Iterable<T>|ArrayLike<T>
 function getEither<T> (in1: Iterable<T>, in2: ArrayLike<T>) {
->getEither : <T>(in1: Iterable<T>, in2: ArrayLike<T>) => Iterable<T> | ArrayLike<T>
+>getEither : <T>(in1: Iterable<T>, in2: ArrayLike<T>) => ArrayLike<T> | Iterable<T>
 >in1 : Iterable<T>
 >in2 : ArrayLike<T>
 
   return Math.random() > 0.5 ? in1 : in2;
->Math.random() > 0.5 ? in1 : in2 : Iterable<T> | ArrayLike<T>
+>Math.random() > 0.5 ? in1 : in2 : ArrayLike<T> | Iterable<T>
 >Math.random() > 0.5 : boolean
 >Math.random() : number
 >Math.random : () => number

tests/baselines/reference/circularReferenceInReturnType.errors.txt

@@ -0,0 +1,19 @@
+circularReferenceInReturnType.ts(3,7): error TS7022: 'res1' implicitly has type 'any' because it does not have a type annotation and is referenced directly or indirectly in its own initializer.
+circularReferenceInReturnType.ts(9,7): error TS7022: 'res3' implicitly has type 'any' because it does not have a type annotation and is referenced directly or indirectly in its own initializer.
+
+
+==== circularReferenceInReturnType.ts (2 errors) ====
+    // inference fails for res1 and res2, but ideally should not
+    declare function fn1<T>(cb: () => T): string;
+    const res1 = fn1(() => res1);
+          ~~~~
+!!! error TS7022: 'res1' implicitly has type 'any' because it does not have a type annotation and is referenced directly or indirectly in its own initializer.
+
+    declare function fn2<T>(): (cb: () => any) => (a: T) => void;
+    const res2 = fn2()(() => res2);
+
+    declare function fn3<T>(): <T2>(cb: (arg: T2) => any) => (a: T) => void;
+    const res3 = fn3()(() => res3);
+          ~~~~
+!!! error TS7022: 'res3' implicitly has type 'any' because it does not have a type annotation and is referenced directly or indirectly in its own initializer.
+

tests/baselines/reference/circularReferenceInReturnType.symbols

@@ -1,41 +1,42 @@
 //// [tests/cases/compiler/circularReferenceInReturnType.ts] ////
 
 === circularReferenceInReturnType.ts ===
+// inference fails for res1 and res2, but ideally should not
 declare function fn1<T>(cb: () => T): string;
 >fn1 : Symbol(fn1, Decl(circularReferenceInReturnType.ts, 0, 0))
->T : Symbol(T, Decl(circularReferenceInReturnType.ts, 0, 21))
->cb : Symbol(cb, Decl(circularReferenceInReturnType.ts, 0, 24))
->T : Symbol(T, Decl(circularReferenceInReturnType.ts, 0, 21))
+>T : Symbol(T, Decl(circularReferenceInReturnType.ts, 1, 21))
+>cb : Symbol(cb, Decl(circularReferenceInReturnType.ts, 1, 24))
+>T : Symbol(T, Decl(circularReferenceInReturnType.ts, 1, 21))
 
 const res1 = fn1(() => res1);
->res1 : Symbol(res1, Decl(circularReferenceInReturnType.ts, 1, 5))
+>res1 : Symbol(res1, Decl(circularReferenceInReturnType.ts, 2, 5))
 >fn1 : Symbol(fn1, Decl(circularReferenceInReturnType.ts, 0, 0))
->res1 : Symbol(res1, Decl(circularReferenceInReturnType.ts, 1, 5))
+>res1 : Symbol(res1, Decl(circularReferenceInReturnType.ts, 2, 5))
 
 declare function fn2<T>(): (cb: () => any) => (a: T) => void;
->fn2 : Symbol(fn2, Decl(circularReferenceInReturnType.ts, 1, 29))
->T : Symbol(T, Decl(circularReferenceInReturnType.ts, 3, 21))
->cb : Symbol(cb, Decl(circularReferenceInReturnType.ts, 3, 28))
->a : Symbol(a, Decl(circularReferenceInReturnType.ts, 3, 47))
->T : Symbol(T, Decl(circularReferenceInReturnType.ts, 3, 21))
+>fn2 : Symbol(fn2, Decl(circularReferenceInReturnType.ts, 2, 29))
+>T : Symbol(T, Decl(circularReferenceInReturnType.ts, 4, 21))
+>cb : Symbol(cb, Decl(circularReferenceInReturnType.ts, 4, 28))
+>a : Symbol(a, Decl(circularReferenceInReturnType.ts, 4, 47))
+>T : Symbol(T, Decl(circularReferenceInReturnType.ts, 4, 21))
 
 const res2 = fn2()(() => res2);
->res2 : Symbol(res2, Decl(circularReferenceInReturnType.ts, 4, 5))
->fn2 : Symbol(fn2, Decl(circularReferenceInReturnType.ts, 1, 29))
->res2 : Symbol(res2, Decl(circularReferenceInReturnType.ts, 4, 5))
+>res2 : Symbol(res2, Decl(circularReferenceInReturnType.ts, 5, 5))
+>fn2 : Symbol(fn2, Decl(circularReferenceInReturnType.ts, 2, 29))
+>res2 : Symbol(res2, Decl(circularReferenceInReturnType.ts, 5, 5))
 
 declare function fn3<T>(): <T2>(cb: (arg: T2) => any) => (a: T) => void;
->fn3 : Symbol(fn3, Decl(circularReferenceInReturnType.ts, 4, 31))
->T : Symbol(T, Decl(circularReferenceInReturnType.ts, 6, 21))
->T2 : Symbol(T2, Decl(circularReferenceInReturnType.ts, 6, 28))
->cb : Symbol(cb, Decl(circularReferenceInReturnType.ts, 6, 32))
->arg : Symbol(arg, Decl(circularReferenceInReturnType.ts, 6, 37))
->T2 : Symbol(T2, Decl(circularReferenceInReturnType.ts, 6, 28))
->a : Symbol(a, Decl(circularReferenceInReturnType.ts, 6, 58))
->T : Symbol(T, Decl(circularReferenceInReturnType.ts, 6, 21))
+>fn3 : Symbol(fn3, Decl(circularReferenceInReturnType.ts, 5, 31))
+>T : Symbol(T, Decl(circularReferenceInReturnType.ts, 7, 21))
+>T2 : Symbol(T2, Decl(circularReferenceInReturnType.ts, 7, 28))
+>cb : Symbol(cb, Decl(circularReferenceInReturnType.ts, 7, 32))
+>arg : Symbol(arg, Decl(circularReferenceInReturnType.ts, 7, 37))
+>T2 : Symbol(T2, Decl(circularReferenceInReturnType.ts, 7, 28))
+>a : Symbol(a, Decl(circularReferenceInReturnType.ts, 7, 58))
+>T : Symbol(T, Decl(circularReferenceInReturnType.ts, 7, 21))
 
 const res3 = fn3()(() => res3);
->res3 : Symbol(res3, Decl(circularReferenceInReturnType.ts, 7, 5))
->fn3 : Symbol(fn3, Decl(circularReferenceInReturnType.ts, 4, 31))
->res3 : Symbol(res3, Decl(circularReferenceInReturnType.ts, 7, 5))
+>res3 : Symbol(res3, Decl(circularReferenceInReturnType.ts, 8, 5))
+>fn3 : Symbol(fn3, Decl(circularReferenceInReturnType.ts, 5, 31))
+>res3 : Symbol(res3, Decl(circularReferenceInReturnType.ts, 8, 5))
 

tests/baselines/reference/circularReferenceInReturnType.types

@@ -1,16 +1,17 @@
 //// [tests/cases/compiler/circularReferenceInReturnType.ts] ////
 
 === circularReferenceInReturnType.ts ===
+// inference fails for res1 and res2, but ideally should not
 declare function fn1<T>(cb: () => T): string;
 >fn1 : <T>(cb: () => T) => string
 >cb : () => T
 
 const res1 = fn1(() => res1);
->res1 : string
+>res1 : any
 >fn1(() => res1) : string
 >fn1 : <T>(cb: () => T) => string
->() => res1 : () => string
->res1 : string
+>() => res1 : () => any
+>res1 : any
 
 declare function fn2<T>(): (cb: () => any) => (a: T) => void;
 >fn2 : <T>() => (cb: () => any) => (a: T) => void
@@ -32,10 +33,10 @@ declare function fn3<T>(): <T2>(cb: (arg: T2) => any) => (a: T) => void;
 >a : T
 
 const res3 = fn3()(() => res3);
->res3 : (a: unknown) => void
+>res3 : any
 >fn3()(() => res3) : (a: unknown) => void
 >fn3() : <T2>(cb: (arg: T2) => any) => (a: unknown) => void
 >fn3 : <T>() => <T2>(cb: (arg: T2) => any) => (a: T) => void
->() => res3 : () => (a: unknown) => void
->res3 : (a: unknown) => void
+>() => res3 : () => any
+>res3 : any
 

tests/baselines/reference/circularReferenceInReturnType2.errors.txt

@@ -0,0 +1,58 @@
+circularReferenceInReturnType2.ts(39,7): error TS7022: 'A' implicitly has type 'any' because it does not have a type annotation and is referenced directly or indirectly in its own initializer.
+
+
+==== circularReferenceInReturnType2.ts (1 errors) ====
+    type ObjectType<Source> = {
+      kind: "object";
+      __source: (source: Source) => void;
+    };
+
+    type Field<Source, Key extends string> = {
+      __key: (key: Key) => void;
+      __source: (source: Source) => void;
+    };
+
+    declare const object: <Source>() => <
+      Fields extends {
+        [Key in keyof Fields]: Field<Source, Key & string>;
+      }
+    >(config: {
+      name: string;
+      fields: Fields | (() => Fields);
+    }) => ObjectType<Source>;
+
+    type InferValueFromObjectType<Type extends ObjectType<any>> =
+      Type extends ObjectType<infer Source> ? Source : never;
+
+    type FieldResolver<Source, TType extends ObjectType<any>> = (
+      source: Source
+    ) => InferValueFromObjectType<TType>;
+
+    type FieldFuncArgs<Source, Type extends ObjectType<any>> = {
+      type: Type;
+      resolve: FieldResolver<Source, Type>;
+    };
+
+    declare const field: <Source, Type extends ObjectType<any>, Key extends string>(
+      field: FieldFuncArgs<Source, Type>
+    ) => Field<Source, Key>;
+
+    type Something = { foo: number };
+
+    // inference fails here, but ideally should not
+    const A = object<Something>()({
+          ~
+!!! error TS7022: 'A' implicitly has type 'any' because it does not have a type annotation and is referenced directly or indirectly in its own initializer.
+      name: "A",
+      fields: () => ({
+        a: field({
+          type: A,
+          resolve() {
+            return {
+              foo: 100,
+            };
+          },
+        }),
+      }),
+    });
+

tests/baselines/reference/circularReferenceInReturnType2.symbols

@@ -126,31 +126,32 @@ type Something = { foo: number };
 >Something : Symbol(Something, Decl(circularReferenceInReturnType2.ts, 33, 24))
 >foo : Symbol(foo, Decl(circularReferenceInReturnType2.ts, 35, 18))
 
+// inference fails here, but ideally should not
 const A = object<Something>()({
->A : Symbol(A, Decl(circularReferenceInReturnType2.ts, 37, 5))
+>A : Symbol(A, Decl(circularReferenceInReturnType2.ts, 38, 5))
 >object : Symbol(object, Decl(circularReferenceInReturnType2.ts, 10, 13))
 >Something : Symbol(Something, Decl(circularReferenceInReturnType2.ts, 33, 24))
 
   name: "A",
->name : Symbol(name, Decl(circularReferenceInReturnType2.ts, 37, 31))
+>name : Symbol(name, Decl(circularReferenceInReturnType2.ts, 38, 31))
 
   fields: () => ({
->fields : Symbol(fields, Decl(circularReferenceInReturnType2.ts, 38, 12))
+>fields : Symbol(fields, Decl(circularReferenceInReturnType2.ts, 39, 12))
 
     a: field({
->a : Symbol(a, Decl(circularReferenceInReturnType2.ts, 39, 18))
+>a : Symbol(a, Decl(circularReferenceInReturnType2.ts, 40, 18))
 >field : Symbol(field, Decl(circularReferenceInReturnType2.ts, 31, 13))
 
       type: A,
->type : Symbol(type, Decl(circularReferenceInReturnType2.ts, 40, 14))
->A : Symbol(A, Decl(circularReferenceInReturnType2.ts, 37, 5))
+>type : Symbol(type, Decl(circularReferenceInReturnType2.ts, 41, 14))
+>A : Symbol(A, Decl(circularReferenceInReturnType2.ts, 38, 5))
 
       resolve() {
->resolve : Symbol(resolve, Decl(circularReferenceInReturnType2.ts, 41, 14))
+>resolve : Symbol(resolve, Decl(circularReferenceInReturnType2.ts, 42, 14))
 
         return {
           foo: 100,
->foo : Symbol(foo, Decl(circularReferenceInReturnType2.ts, 43, 16))
+>foo : Symbol(foo, Decl(circularReferenceInReturnType2.ts, 44, 16))
 
         };
       },

tests/baselines/reference/circularReferenceInReturnType2.types

@@ -79,8 +79,9 @@ type Something = { foo: number };
 >Something : { foo: number; }
 >foo : number
 
+// inference fails here, but ideally should not
 const A = object<Something>()({
->A : ObjectType<Something>
+>A : any
 >object<Something>()({  name: "A",  fields: () => ({    a: field({      type: A,      resolve() {        return {          foo: 100,        };      },    }),  }),}) : ObjectType<Something>
 >object<Something>() : <Fields extends { [Key in keyof Fields]: Field<Something, Key & string>; }>(config: { name: string; fields: Fields | (() => Fields); }) => ObjectType<Something>
 >object : <Source>() => <Fields extends { [Key in keyof Fields]: Field<Source, Key & string>; }>(config: { name: string; fields: Fields | (() => Fields); }) => ObjectType<Source>
@@ -100,11 +101,11 @@ const A = object<Something>()({
 >a : Field<Something, "a">
 >field({      type: A,      resolve() {        return {          foo: 100,        };      },    }) : Field<Something, "a">
 >field : <Source, Type extends ObjectType<any>, Key extends string>(field: FieldFuncArgs<Source, Type>) => Field<Source, Key>
->{      type: A,      resolve() {        return {          foo: 100,        };      },    } : { type: ObjectType<Something>; resolve(): { foo: number; }; }
+>{      type: A,      resolve() {        return {          foo: 100,        };      },    } : { type: any; resolve(): { foo: number; }; }
 
       type: A,
->type : ObjectType<Something>
->A : ObjectType<Something>
+>type : any
+>A : any
 
       resolve() {
 >resolve : () => { foo: number; }

tests/cases/compiler/circularReferenceInReturnType.ts

@@ -1,6 +1,7 @@
 // @strict: true
 // @noEmit: true
 
+// inference fails for res1 and res2, but ideally should not
 declare function fn1<T>(cb: () => T): string;
 const res1 = fn1(() => res1);
 

tests/cases/compiler/circularReferenceInReturnType2.ts

@@ -38,6 +38,7 @@ declare const field: <Source, Type extends ObjectType<any>, Key extends string>(
 
 type Something = { foo: number };
 
+// inference fails here, but ideally should not
 const A = object<Something>()({
   name: "A",
   fields: () => ({