Merge pull request #31354 from microsoft/deferConditionalTypes

Defer resolution of true and false branches in conditional types
microsoft · May 14, 2019 · fb6ae38 · fb6ae38
2 parents 70950cb + 066e4b6
commit fb6ae38
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Showing 11 changed files with 226 additions and 208 deletions.
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
@@ -3966,6 +3966,8 @@ namespace ts {
         StructuredOrInstantiable = StructuredType | Instantiable,
         /* @internal */
         ObjectFlagsType = Nullable | Never | Object | Union | Intersection,
+        /* @internal */
+        Simplifiable = IndexedAccess | Conditional | Substitution,
         // 'Narrowable' types are types where narrowing actually narrows.
         // This *should* be every type other than null, undefined, void, and never
         Narrowable = Any | Unknown | StructuredOrInstantiable | StringLike | NumberLike | BigIntLike | BooleanLike | ESSymbol | UniqueESSymbol | NonPrimitive,
@@ -4338,8 +4340,8 @@ namespace ts {
         root: ConditionalRoot;
         checkType: Type;
         extendsType: Type;
-        trueType: Type;
-        falseType: Type;
+        resolvedTrueType: Type;
+        resolvedFalseType: Type;
         /* @internal */
         resolvedInferredTrueType?: Type; // The `trueType` instantiated with the `combinedMapper`, if present
         /* @internal */

diff --git a/tests/baselines/reference/api/tsserverlibrary.d.ts b/tests/baselines/reference/api/tsserverlibrary.d.ts
@@ -2390,8 +2390,8 @@ declare namespace ts {
         root: ConditionalRoot;
         checkType: Type;
         extendsType: Type;
-        trueType: Type;
-        falseType: Type;
+        resolvedTrueType: Type;
+        resolvedFalseType: Type;
     }
     interface SubstitutionType extends InstantiableType {
         typeVariable: TypeVariable;

diff --git a/tests/baselines/reference/api/typescript.d.ts b/tests/baselines/reference/api/typescript.d.ts
@@ -2390,8 +2390,8 @@ declare namespace ts {
         root: ConditionalRoot;
         checkType: Type;
         extendsType: Type;
-        trueType: Type;
-        falseType: Type;
+        resolvedTrueType: Type;
+        resolvedFalseType: Type;
     }
     interface SubstitutionType extends InstantiableType {
         typeVariable: TypeVariable;

diff --git a/...rcularlyConstrainedMappedTypeContainingConditionalNoInfiniteInstantiationDepth.errors.txt b/...rcularlyConstrainedMappedTypeContainingConditionalNoInfiniteInstantiationDepth.errors.txt
diff --git a/tests/baselines/reference/conditionalTypes1.js b/tests/baselines/reference/conditionalTypes1.js
@@ -645,7 +645,7 @@ declare type T82 = Eq2<false, true>;
 declare type T83 = Eq2<false, false>;
 declare type Foo<T> = T extends string ? boolean : number;
 declare type Bar<T> = T extends string ? boolean : number;
-declare const convert: <U>(value: Foo<U>) => Foo<U>;
+declare const convert: <U>(value: Foo<U>) => Bar<U>;
 declare type Baz<T> = Foo<T>;
 declare const convert2: <T>(value: Foo<T>) => Foo<T>;
 declare function f31<T>(): void;

diff --git a/tests/baselines/reference/conditionalTypes1.types b/tests/baselines/reference/conditionalTypes1.types
@@ -779,8 +779,8 @@ type Bar<T> = T extends string ? boolean : number;
 >Bar : Bar<T>
 
 const convert = <U>(value: Foo<U>): Bar<U> => value;
->convert : <U>(value: Foo<U>) => Foo<U>
-><U>(value: Foo<U>): Bar<U> => value : <U>(value: Foo<U>) => Foo<U>
+>convert : <U>(value: Foo<U>) => Bar<U>
+><U>(value: Foo<U>): Bar<U> => value : <U>(value: Foo<U>) => Bar<U>
 >value : Foo<U>
 >value : Foo<U>
 
@@ -832,7 +832,7 @@ function f33<T, U>() {
 >T1 : Foo<T & U>
 
     type T2 = Bar<T & U>;
->T2 : Foo<T & U>
+>T2 : Bar<T & U>
 
     var z: T1;
 >z : Foo<T & U>

diff --git a/tests/baselines/reference/conditionalTypes2.errors.txt b/tests/baselines/reference/conditionalTypes2.errors.txt
@@ -10,13 +10,13 @@ tests/cases/conformance/types/conditional/conditionalTypes2.ts(24,5): error TS23
       Type 'keyof B' is not assignable to type 'keyof A'.
         Type 'string | number | symbol' is not assignable to type 'keyof A'.
           Type 'string' is not assignable to type 'keyof A'.
-            Type 'string' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
-              Type 'keyof B' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
-                Type 'string | number | symbol' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
-                  Type 'string' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
-                    Type 'keyof B' is not assignable to type '"valueOf"'.
-                      Type 'string | number | symbol' is not assignable to type '"valueOf"'.
-                        Type 'string' is not assignable to type '"valueOf"'.
+            Type 'string' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf" | keyof A'.
+              Type 'keyof B' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf" | keyof A'.
+                Type 'string | number | symbol' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf" | keyof A'.
+                  Type 'string' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf" | keyof A'.
+                    Type 'keyof B' is not assignable to type 'keyof A'.
+                      Type 'string | number | symbol' is not assignable to type 'keyof A'.
+                        Type 'string' is not assignable to type 'keyof A'.
 tests/cases/conformance/types/conditional/conditionalTypes2.ts(25,5): error TS2322: Type 'Invariant<A>' is not assignable to type 'Invariant<B>'.
   Types of property 'foo' are incompatible.
     Type 'A extends string ? keyof A : A' is not assignable to type 'B extends string ? keyof B : B'.
@@ -73,13 +73,13 @@ tests/cases/conformance/types/conditional/conditionalTypes2.ts(75,12): error TS2
 !!! error TS2322:       Type 'keyof B' is not assignable to type 'keyof A'.
 !!! error TS2322:         Type 'string | number | symbol' is not assignable to type 'keyof A'.
 !!! error TS2322:           Type 'string' is not assignable to type 'keyof A'.
-!!! error TS2322:             Type 'string' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
-!!! error TS2322:               Type 'keyof B' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
-!!! error TS2322:                 Type 'string | number | symbol' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
-!!! error TS2322:                   Type 'string' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
-!!! error TS2322:                     Type 'keyof B' is not assignable to type '"valueOf"'.
-!!! error TS2322:                       Type 'string | number | symbol' is not assignable to type '"valueOf"'.
-!!! error TS2322:                         Type 'string' is not assignable to type '"valueOf"'.
+!!! error TS2322:             Type 'string' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf" | keyof A'.
+!!! error TS2322:               Type 'keyof B' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf" | keyof A'.
+!!! error TS2322:                 Type 'string | number | symbol' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf" | keyof A'.
+!!! error TS2322:                   Type 'string' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf" | keyof A'.
+!!! error TS2322:                     Type 'keyof B' is not assignable to type 'keyof A'.
+!!! error TS2322:                       Type 'string | number | symbol' is not assignable to type 'keyof A'.
+!!! error TS2322:                         Type 'string' is not assignable to type 'keyof A'.
         b = a;  // Error
         ~
 !!! error TS2322: Type 'Invariant<A>' is not assignable to type 'Invariant<B>'.

diff --git a/tests/baselines/reference/conditionalTypesSimplifyWhenTrivial.types b/tests/baselines/reference/conditionalTypesSimplifyWhenTrivial.types
@@ -1,49 +1,49 @@
 === tests/cases/compiler/conditionalTypesSimplifyWhenTrivial.ts ===
 const fn1 = <Params>(
->fn1 : <Params>(params: Pick<Params, keyof Params>) => Params
-><Params>(    params: Pick<Params, Exclude<keyof Params, never>>,): Params => params : <Params>(params: Pick<Params, keyof Params>) => Params
+>fn1 : <Params>(params: Pick<Params, Exclude<keyof Params, never>>) => Params
+><Params>(    params: Pick<Params, Exclude<keyof Params, never>>,): Params => params : <Params>(params: Pick<Params, Exclude<keyof Params, never>>) => Params
 
     params: Pick<Params, Exclude<keyof Params, never>>,
->params : Pick<Params, keyof Params>
+>params : Pick<Params, Exclude<keyof Params, never>>
 
 ): Params => params;
->params : Pick<Params, keyof Params>
+>params : Pick<Params, Exclude<keyof Params, never>>
 
 function fn2<T>(x: Exclude<T, never>) {
->fn2 : <T>(x: T) => void
->x : T
+>fn2 : <T>(x: Exclude<T, never>) => void
+>x : Exclude<T, never>
 
     var y: T = x;
 >y : T
->x : T
+>x : Exclude<T, never>
 
     x = y;
 >x = y : T
->x : T
+>x : Exclude<T, never>
 >y : T
 }
 
 const fn3 = <Params>(
->fn3 : <Params>(params: Pick<Params, keyof Params>) => Params
-><Params>(    params: Pick<Params, Extract<keyof Params, keyof Params>>,): Params => params : <Params>(params: Pick<Params, keyof Params>) => Params
+>fn3 : <Params>(params: Pick<Params, Extract<keyof Params, keyof Params>>) => Params
+><Params>(    params: Pick<Params, Extract<keyof Params, keyof Params>>,): Params => params : <Params>(params: Pick<Params, Extract<keyof Params, keyof Params>>) => Params
 
     params: Pick<Params, Extract<keyof Params, keyof Params>>,
->params : Pick<Params, keyof Params>
+>params : Pick<Params, Extract<keyof Params, keyof Params>>
 
 ): Params => params;
->params : Pick<Params, keyof Params>
+>params : Pick<Params, Extract<keyof Params, keyof Params>>
 
 function fn4<T>(x: Extract<T, T>) {
->fn4 : <T>(x: T) => void
->x : T
+>fn4 : <T>(x: Extract<T, T>) => void
+>x : Extract<T, T>
 
     var y: T = x;
 >y : T
->x : T
+>x : Extract<T, T>
 
     x = y;
 >x = y : T
->x : T
+>x : Extract<T, T>
 >y : T
 }
 
@@ -57,101 +57,101 @@ type ExcludeWithDefault<T, U, D = never> = T extends U ? D : T;
 >ExcludeWithDefault : ExcludeWithDefault<T, U, D>
 
 const fn5 = <Params>(
->fn5 : <Params>(params: Pick<Params, keyof Params>) => Params
-><Params>(    params: Pick<Params, ExcludeWithDefault<keyof Params, never>>,): Params => params : <Params>(params: Pick<Params, keyof Params>) => Params
+>fn5 : <Params>(params: Pick<Params, ExcludeWithDefault<keyof Params, never, never>>) => Params
+><Params>(    params: Pick<Params, ExcludeWithDefault<keyof Params, never>>,): Params => params : <Params>(params: Pick<Params, ExcludeWithDefault<keyof Params, never, never>>) => Params
 
     params: Pick<Params, ExcludeWithDefault<keyof Params, never>>,
->params : Pick<Params, keyof Params>
+>params : Pick<Params, ExcludeWithDefault<keyof Params, never, never>>
 
 ): Params => params;
->params : Pick<Params, keyof Params>
+>params : Pick<Params, ExcludeWithDefault<keyof Params, never, never>>
 
 function fn6<T>(x: ExcludeWithDefault<T, never>) {
->fn6 : <T>(x: T) => void
->x : T
+>fn6 : <T>(x: ExcludeWithDefault<T, never, never>) => void
+>x : ExcludeWithDefault<T, never, never>
 
     var y: T = x;
 >y : T
->x : T
+>x : ExcludeWithDefault<T, never, never>
 
     x = y;
 >x = y : T
->x : T
+>x : ExcludeWithDefault<T, never, never>
 >y : T
 }
 
 const fn7 = <Params>(
->fn7 : <Params>(params: Pick<Params, keyof Params>) => Params
-><Params>(    params: Pick<Params, ExtractWithDefault<keyof Params, keyof Params>>,): Params => params : <Params>(params: Pick<Params, keyof Params>) => Params
+>fn7 : <Params>(params: Pick<Params, ExtractWithDefault<keyof Params, keyof Params, never>>) => Params
+><Params>(    params: Pick<Params, ExtractWithDefault<keyof Params, keyof Params>>,): Params => params : <Params>(params: Pick<Params, ExtractWithDefault<keyof Params, keyof Params, never>>) => Params
 
     params: Pick<Params, ExtractWithDefault<keyof Params, keyof Params>>,
->params : Pick<Params, keyof Params>
+>params : Pick<Params, ExtractWithDefault<keyof Params, keyof Params, never>>
 
 ): Params => params;
->params : Pick<Params, keyof Params>
+>params : Pick<Params, ExtractWithDefault<keyof Params, keyof Params, never>>
 
 function fn8<T>(x: ExtractWithDefault<T, T>) {
->fn8 : <T>(x: T) => void
->x : T
+>fn8 : <T>(x: ExtractWithDefault<T, T, never>) => void
+>x : ExtractWithDefault<T, T, never>
 
     var y: T = x;
 >y : T
->x : T
+>x : ExtractWithDefault<T, T, never>
 
     x = y;
 >x = y : T
->x : T
+>x : ExtractWithDefault<T, T, never>
 >y : T
 }
 
 type TemplatedConditional<TCheck, TExtends, TTrue, TFalse> = TCheck extends TExtends ? TTrue : TFalse;
 >TemplatedConditional : TemplatedConditional<TCheck, TExtends, TTrue, TFalse>
 
 const fn9 = <Params>(
->fn9 : <Params>(params: Pick<Params, keyof Params>) => Params
-><Params>(    params: Pick<Params, TemplatedConditional<keyof Params, never, never, keyof Params>>,): Params => params : <Params>(params: Pick<Params, keyof Params>) => Params
+>fn9 : <Params>(params: Pick<Params, TemplatedConditional<keyof Params, never, never, keyof Params>>) => Params
+><Params>(    params: Pick<Params, TemplatedConditional<keyof Params, never, never, keyof Params>>,): Params => params : <Params>(params: Pick<Params, TemplatedConditional<keyof Params, never, never, keyof Params>>) => Params
 
     params: Pick<Params, TemplatedConditional<keyof Params, never, never, keyof Params>>,
->params : Pick<Params, keyof Params>
+>params : Pick<Params, TemplatedConditional<keyof Params, never, never, keyof Params>>
 
 ): Params => params;
->params : Pick<Params, keyof Params>
+>params : Pick<Params, TemplatedConditional<keyof Params, never, never, keyof Params>>
 
 function fn10<T>(x: TemplatedConditional<T, never, never, T>) {
->fn10 : <T>(x: T) => void
->x : T
+>fn10 : <T>(x: TemplatedConditional<T, never, never, T>) => void
+>x : TemplatedConditional<T, never, never, T>
 
     var y: T = x;
 >y : T
->x : T
+>x : TemplatedConditional<T, never, never, T>
 
     x = y;
 >x = y : T
->x : T
+>x : TemplatedConditional<T, never, never, T>
 >y : T
 }
 
 const fn11 = <Params>(
->fn11 : <Params>(params: Pick<Params, keyof Params>) => Params
-><Params>(    params: Pick<Params, TemplatedConditional<keyof Params, keyof Params, keyof Params, never>>,): Params => params : <Params>(params: Pick<Params, keyof Params>) => Params
+>fn11 : <Params>(params: Pick<Params, TemplatedConditional<keyof Params, keyof Params, keyof Params, never>>) => Params
+><Params>(    params: Pick<Params, TemplatedConditional<keyof Params, keyof Params, keyof Params, never>>,): Params => params : <Params>(params: Pick<Params, TemplatedConditional<keyof Params, keyof Params, keyof Params, never>>) => Params
 
     params: Pick<Params, TemplatedConditional<keyof Params, keyof Params, keyof Params, never>>,
->params : Pick<Params, keyof Params>
+>params : Pick<Params, TemplatedConditional<keyof Params, keyof Params, keyof Params, never>>
 
 ): Params => params;
->params : Pick<Params, keyof Params>
+>params : Pick<Params, TemplatedConditional<keyof Params, keyof Params, keyof Params, never>>
 
 function fn12<T>(x: TemplatedConditional<T, T, T, never>) {
->fn12 : <T>(x: T) => void
->x : T
+>fn12 : <T>(x: TemplatedConditional<T, T, T, never>) => void
+>x : TemplatedConditional<T, T, T, never>
 
     var y: T = x;
 >y : T
->x : T
+>x : TemplatedConditional<T, T, T, never>
 
     x = y;
 >x = y : T
->x : T
+>x : TemplatedConditional<T, T, T, never>
 >y : T
 }
 

diff --git a/tests/baselines/reference/inlinedAliasAssignableToConstraintSameAsAlias.types b/tests/baselines/reference/inlinedAliasAssignableToConstraintSameAsAlias.types
@@ -31,7 +31,7 @@ class A {
 >z : A[]
 
   whereRelated< // Works // Type is same as A1, but is not assignable to type A
->whereRelated : <RF extends RelationFields = RelationFields, N extends "x" | "y" | "z" = "x" | "y" | "z", A1 extends A = RF[N] extends A[] ? RF[N][0] : never, A2 extends A = RF[N] extends A[] ? RF[N][0] : never>() => number
+>whereRelated : <RF extends RelationFields = RelationFields, N extends "x" | "y" | "z" = "x" | "y" | "z", A1 extends A = RF[N] extends A[] ? RF[N][0] : never, A2 extends A = ShouldA<RF, N>>() => number
 
     RF extends RelationFields = RelationFields,
     N extends Name = Name,