Create type aliases for unresolved type symbols (#45976)

* Create type aliases for unresolved type symbols

* Accept new baselines

* Update fourslash tests

* Unresolved import aliases create tagged unresolved symbols

* Add comments

* Accept new baselines

* Add fourslash tests

Author: ahejlsberg

src/compiler/checker.ts

@@ -4957,6 +4957,7 @@ namespace ts {
         HasNeverType      = 1 << 17,        // Synthetic property with at least one never type in constituents
         Mapped            = 1 << 18,        // Property of mapped type
         StripOptional     = 1 << 19,        // Strip optionality in mapped property
+        Unresolved        = 1 << 20,        // Unresolved type alias symbol
         Synthetic = SyntheticProperty | SyntheticMethod,
         Discriminant = HasNonUniformType | HasLiteralType,
         Partial = ReadPartial | WritePartial

src/compiler/types.ts

@@ -2,5 +2,6 @@
 var v = (a: ) => {
 >v : Symbol(v, Decl(ArrowFunction1.ts, 0, 3))
 >a : Symbol(a, Decl(ArrowFunction1.ts, 0, 9))
+> : Symbol(unknown)
 
 };

tests/baselines/reference/ArrowFunction1.symbols

@@ -19,6 +19,7 @@ module clodule1 {
     function f(x: T) { }
 >f : Symbol(f, Decl(ClassAndModuleThatMergeWithModuleMemberThatUsesClassTypeParameter.ts, 8, 17))
 >x : Symbol(x, Decl(ClassAndModuleThatMergeWithModuleMemberThatUsesClassTypeParameter.ts, 9, 15))
+>T : Symbol(T)
 }
 
 class clodule2<T>{
@@ -38,10 +39,12 @@ module clodule2 {
 
     var x: T;
 >x : Symbol(x, Decl(ClassAndModuleThatMergeWithModuleMemberThatUsesClassTypeParameter.ts, 19, 7))
+>T : Symbol(T)
 
     class D<U extends T>{
 >D : Symbol(D, Decl(ClassAndModuleThatMergeWithModuleMemberThatUsesClassTypeParameter.ts, 19, 13))
 >U : Symbol(U, Decl(ClassAndModuleThatMergeWithModuleMemberThatUsesClassTypeParameter.ts, 21, 12))
+>T : Symbol(T)
 
         id: string;
 >id : Symbol(D.id, Decl(ClassAndModuleThatMergeWithModuleMemberThatUsesClassTypeParameter.ts, 21, 25))
@@ -92,6 +95,7 @@ module clodule4 {
 
         name: T;
 >name : Symbol(D.name, Decl(ClassAndModuleThatMergeWithModuleMemberThatUsesClassTypeParameter.ts, 44, 13))
+>T : Symbol(T)
     }
 }
 

tests/baselines/reference/ClassAndModuleThatMergeWithModuleMemberThatUsesClassTypeParameter.symbols

@@ -15,8 +15,8 @@ module clodule1 {
 >clodule1 : typeof clodule1
 
     function f(x: T) { }
->f : (x: any) => void
->x : any
+>f : (x: T) => void
+>x : T
 }
 
 class clodule2<T>{
@@ -33,7 +33,7 @@ module clodule2 {
 >clodule2 : typeof clodule2
 
     var x: T;
->x : any
+>x : T
 
     class D<U extends T>{
 >D : D<U>
@@ -83,7 +83,7 @@ module clodule4 {
 >D : D
 
         name: T;
->name : any
+>name : T
     }
 }
 

tests/baselines/reference/ClassAndModuleThatMergeWithModuleMemberThatUsesClassTypeParameter.types

@@ -5,5 +5,6 @@ function * foo() {
    // Legal to use 'yield' in a type context.
    var v: yield;
 >v : Symbol(v, Decl(FunctionDeclaration13_es6.ts, 2, 6))
+>yield : Symbol(yield)
 }
 

tests/baselines/reference/FunctionDeclaration13_es6.symbols

@@ -4,6 +4,6 @@ function * foo() {
 
    // Legal to use 'yield' in a type context.
    var v: yield;
->v : any
+>v : yield
 }
 

tests/baselines/reference/FunctionDeclaration13_es6.types

@@ -2,4 +2,5 @@
 function A(): (public B) => C {
 >A : Symbol(A, Decl(ParameterList5.ts, 0, 0))
 >B : Symbol(B, Decl(ParameterList5.ts, 0, 15))
+>C : Symbol(C)
 }

tests/baselines/reference/ParameterList5.symbols

@@ -1,5 +1,5 @@
 === tests/cases/compiler/ParameterList5.ts ===
 function A(): (public B) => C {
->A : () => (B: any) => any
+>A : () => (B: any) => C
 >B : any
 }

tests/baselines/reference/ParameterList5.types

@@ -1,4 +1,5 @@
 === tests/cases/conformance/parser/ecmascript5/TupleTypes/TupleType6.ts ===
 var v: [number,,]
 >v : Symbol(v, Decl(TupleType6.ts, 0, 3))
+> : Symbol(unknown)
 

tests/baselines/reference/TupleType6.symbols

@@ -48,6 +48,7 @@ export module A {
     // collision with 'Origin' var in other part of merged module
     export var Origin: Point = { x: 0, y: 0 };
 >Origin : Symbol(Origin, Decl(part2.ts, 2, 14))
+>Point : Symbol(Point)
 >x : Symbol(x, Decl(part2.ts, 2, 32))
 >y : Symbol(y, Decl(part2.ts, 2, 38))
 
@@ -59,7 +60,9 @@ export module A {
 
             constructor(public tl: Point, public br: Point) { }
 >tl : Symbol(Plane.tl, Decl(part2.ts, 6, 24))
+>Point : Symbol(Point)
 >br : Symbol(Plane.br, Decl(part2.ts, 6, 41))
+>Point : Symbol(Point)
         }
     }
 }

tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedLocalVarsOfTheSameName.symbols

@@ -45,7 +45,7 @@ export module A {
 
     // collision with 'Origin' var in other part of merged module
     export var Origin: Point = { x: 0, y: 0 };
->Origin : any
+>Origin : Point
 >{ x: 0, y: 0 } : { x: number; y: number; }
 >x : number
 >0 : 0
@@ -59,8 +59,8 @@ export module A {
 >Plane : Plane
 
             constructor(public tl: Point, public br: Point) { }
->tl : any
->br : any
+>tl : Point
+>br : Point
         }
     }
 }

tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedLocalVarsOfTheSameName.types

@@ -5,4 +5,5 @@ export class Q {
     set bet(arg: DoesNotExist) {}
 >bet : Symbol(Q.bet, Decl(accessorDeclarationEmitVisibilityErrors.ts, 0, 16))
 >arg : Symbol(arg, Decl(accessorDeclarationEmitVisibilityErrors.ts, 1, 12))
+>DoesNotExist : Symbol(DoesNotExist)
 }

tests/baselines/reference/accessorDeclarationEmitVisibilityErrors.symbols

@@ -3,6 +3,6 @@ export class Q {
 >Q : Q
 
     set bet(arg: DoesNotExist) {}
->bet : any
->arg : any
+>bet : DoesNotExist
+>arg : DoesNotExist
 }

tests/baselines/reference/accessorDeclarationEmitVisibilityErrors.types

@@ -44,6 +44,7 @@ function use() {
   var p3:booz.bar;
 >p3 : Symbol(p3, Decl(aliasBug.ts, 15, 5))
 >booz : Symbol(booz, Decl(aliasBug.ts, 7, 21))
+>bar : Symbol(booz.bar)
 
   var p22 = new provide.Provide();
 >p22 : Symbol(p22, Decl(aliasBug.ts, 16, 5))

tests/baselines/reference/aliasBug.symbols

@@ -41,7 +41,7 @@ function use() {
 >foo : any
 
   var p3:booz.bar;
->p3 : any
+>p3 : booz.bar
 >booz : any
 
   var p22 = new provide.Provide();

tests/baselines/reference/aliasBug.types

@@ -74,6 +74,7 @@ function use() {
   var p3:booz.bar;
 >p3 : Symbol(p3, Decl(aliasErrors.ts, 25, 5))
 >booz : Symbol(booz, Decl(aliasErrors.ts, 6, 21))
+>bar : Symbol(booz.bar)
 
   var p22 = new provide.Provide();
 >p22 : Symbol(p22, Decl(aliasErrors.ts, 26, 5))

tests/baselines/reference/aliasErrors.symbols

@@ -81,7 +81,7 @@ function use() {
 >foo : any
 
   var p3:booz.bar;
->p3 : any
+>p3 : booz.bar
 >booz : any
 
   var p22 = new provide.Provide();

tests/baselines/reference/aliasErrors.types

@@ -47,5 +47,6 @@ originalZZZ;
 
 const y: originalZZZ = x;
 >y : Symbol(y, Decl(index.ts, 8, 5))
+>originalZZZ : Symbol(originalZZZ)
 >x : Symbol(x, Decl(index.ts, 2, 5))
 

tests/baselines/reference/allowImportClausesToMergeWithTypes.symbols

@@ -48,6 +48,6 @@ originalZZZ;
 >originalZZZ : 123
 
 const y: originalZZZ = x;
->y : any
+>y : originalZZZ
 >x : zzz
 

tests/baselines/reference/allowImportClausesToMergeWithTypes.types

@@ -17,7 +17,7 @@ declare module "OuterModule" {
         public x: m2.c;
 >x : Symbol(SubModule.x, Decl(ambientExternalModuleWithRelativeExternalImportDeclaration.ts, 4, 35))
 >m2 : Symbol(m2, Decl(ambientExternalModuleWithRelativeExternalImportDeclaration.ts, 0, 30))
->c : Symbol(m2)
+>c : Symbol(m2.c)
 
         constructor();
     }

tests/baselines/reference/ambientExternalModuleWithRelativeExternalImportDeclaration.symbols

@@ -15,7 +15,7 @@ declare module "OuterModule" {
 >InstanceVar : number
 
         public x: m2.c;
->x : any
+>x : m2.c
 >m2 : any
 
         constructor();

tests/baselines/reference/ambientExternalModuleWithRelativeExternalImportDeclaration.types

@@ -44,6 +44,7 @@ assertEqual(animal.type, 'cat' as const);
 >animal.type : Symbol(type, Decl(assertionFunctionsCanNarrowByDiscriminant.ts, 0, 15), Decl(assertionFunctionsCanNarrowByDiscriminant.ts, 5, 15))
 >animal : Symbol(animal, Decl(assertionFunctionsCanNarrowByDiscriminant.ts, 14, 5))
 >type : Symbol(type, Decl(assertionFunctionsCanNarrowByDiscriminant.ts, 0, 15), Decl(assertionFunctionsCanNarrowByDiscriminant.ts, 5, 15))
+>const : Symbol(const)
 
 animal.canMeow; // since is cat, should not be an error
 >animal.canMeow : Symbol(Cat.canMeow, Decl(assertionFunctionsCanNarrowByDiscriminant.ts, 1, 16))
@@ -61,6 +62,7 @@ assertEqual(animalOrUndef?.type, 'cat' as const);
 >animalOrUndef?.type : Symbol(type, Decl(assertionFunctionsCanNarrowByDiscriminant.ts, 0, 15), Decl(assertionFunctionsCanNarrowByDiscriminant.ts, 5, 15))
 >animalOrUndef : Symbol(animalOrUndef, Decl(assertionFunctionsCanNarrowByDiscriminant.ts, 19, 5))
 >type : Symbol(type, Decl(assertionFunctionsCanNarrowByDiscriminant.ts, 0, 15), Decl(assertionFunctionsCanNarrowByDiscriminant.ts, 5, 15))
+>const : Symbol(const)
 
 animalOrUndef.canMeow; // since is cat, should not be an error
 >animalOrUndef.canMeow : Symbol(Cat.canMeow, Decl(assertionFunctionsCanNarrowByDiscriminant.ts, 1, 16))

tests/baselines/reference/assertionFunctionsCanNarrowByDiscriminant.symbols

@@ -17,6 +17,7 @@ interface Derived2 extends Derived { baz: string; }
 
 var a: A;
 >a : Symbol(a, Decl(assignmentCompatWithStringIndexer3.ts, 6, 3))
+>A : Symbol(A)
 
 var b1: { [x: string]: string; }
 >b1 : Symbol(b1, Decl(assignmentCompatWithStringIndexer3.ts, 7, 3))

tests/baselines/reference/assignmentCompatWithStringIndexer3.symbols

@@ -11,21 +11,21 @@ interface Derived2 extends Derived { baz: string; }
 >baz : string
 
 var a: A;
->a : any
+>a : A
 
 var b1: { [x: string]: string; }
 >b1 : { [x: string]: string; }
 >x : string
 
 a = b1; // error
 >a = b1 : { [x: string]: string; }
->a : any
+>a : A
 >b1 : { [x: string]: string; }
 
 b1 = a; // error
->b1 = a : any
+>b1 = a : A
 >b1 : { [x: string]: string; }
->a : any
+>a : A
 
 module Generics {
 >Generics : typeof Generics

tests/baselines/reference/assignmentCompatWithStringIndexer3.types

@@ -6,5 +6,6 @@ var foo = async (): Promise<void> => {
    // Legal to use 'await' in a type context.
    var v: await;
 >v : Symbol(v, Decl(asyncArrowFunction10_es2017.ts, 2, 6))
+>await : Symbol(await)
 }
 

tests/baselines/reference/asyncArrowFunction10_es2017.symbols

@@ -5,6 +5,6 @@ var foo = async (): Promise<void> => {
 
    // Legal to use 'await' in a type context.
    var v: await;
->v : any
+>v : await
 }
 

tests/baselines/reference/asyncArrowFunction10_es2017.types

@@ -6,5 +6,6 @@ var foo = async (): Promise<void> => {
    // Legal to use 'await' in a type context.
    var v: await;
 >v : Symbol(v, Decl(asyncArrowFunction10_es5.ts, 2, 6))
+>await : Symbol(await)
 }
 

tests/baselines/reference/asyncArrowFunction10_es5.symbols

@@ -5,6 +5,6 @@ var foo = async (): Promise<void> => {
 
    // Legal to use 'await' in a type context.
    var v: await;
->v : any
+>v : await
 }
 

tests/baselines/reference/asyncArrowFunction10_es5.types

@@ -6,5 +6,6 @@ var foo = async (): Promise<void> => {
    // Legal to use 'await' in a type context.
    var v: await;
 >v : Symbol(v, Decl(asyncArrowFunction10_es6.ts, 2, 6))
+>await : Symbol(await)
 }
 

tests/baselines/reference/asyncArrowFunction10_es6.symbols

@@ -5,6 +5,6 @@ var foo = async (): Promise<void> => {
 
    // Legal to use 'await' in a type context.
    var v: await;
->v : any
+>v : await
 }