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Port PR #30877 #30904

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Apr 16, 2019
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4 changes: 2 additions & 2 deletions src/compiler/checker.ts
Original file line number Diff line number Diff line change
@@ -10163,15 +10163,15 @@ namespace ts {

function getConditionalTypeWorker(root: ConditionalRoot, mapper: TypeMapper | undefined, checkType: Type, extendsType: Type, trueType: Type, falseType: Type) {
// Simplifications for types of the form `T extends U ? T : never` and `T extends U ? never : T`.
if (falseType.flags & TypeFlags.Never && isTypeIdenticalTo(getActualTypeVariable(trueType), getActualTypeVariable(checkType))) {
if (falseType.flags & TypeFlags.Never && getActualTypeVariable(trueType) === getActualTypeVariable(checkType)) {
if (checkType.flags & TypeFlags.Any || isTypeAssignableTo(getRestrictiveInstantiation(checkType), getRestrictiveInstantiation(extendsType))) { // Always true
return trueType;
}
else if (isIntersectionEmpty(checkType, extendsType)) { // Always false
return neverType;
}
}
else if (trueType.flags & TypeFlags.Never && isTypeIdenticalTo(getActualTypeVariable(falseType), getActualTypeVariable(checkType))) {
else if (trueType.flags & TypeFlags.Never && getActualTypeVariable(falseType) === getActualTypeVariable(checkType)) {
if (!(checkType.flags & TypeFlags.Any) && isTypeAssignableTo(getRestrictiveInstantiation(checkType), getRestrictiveInstantiation(extendsType))) { // Always true
return neverType;
}
15 changes: 15 additions & 0 deletions tests/baselines/reference/conditionalTypeSimplification.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,15 @@
//// [conditionalTypeSimplification.ts]
// Repro from #30794

interface AbstractSchema<S, V> {
m1<T> (v: T): SchemaType<S, Exclude<V, T>>;
m2<T> (v: T): SchemaType<S, T>;
}

type SchemaType<S, V> = S extends object ? AnySchema<V> : never;
interface AnySchema<V> extends AnySchemaType<AnySchema<undefined>, V> { }
interface AnySchemaType<S extends AbstractSchema<any, any>, V> extends AbstractSchema<S, V> { }


//// [conditionalTypeSimplification.js]
// Repro from #30794
53 changes: 53 additions & 0 deletions tests/baselines/reference/conditionalTypeSimplification.symbols
Original file line number Diff line number Diff line change
@@ -0,0 +1,53 @@
=== tests/cases/compiler/conditionalTypeSimplification.ts ===
// Repro from #30794

interface AbstractSchema<S, V> {
>AbstractSchema : Symbol(AbstractSchema, Decl(conditionalTypeSimplification.ts, 0, 0))
>S : Symbol(S, Decl(conditionalTypeSimplification.ts, 2, 25))
>V : Symbol(V, Decl(conditionalTypeSimplification.ts, 2, 27))

m1<T> (v: T): SchemaType<S, Exclude<V, T>>;
>m1 : Symbol(AbstractSchema.m1, Decl(conditionalTypeSimplification.ts, 2, 32))
>T : Symbol(T, Decl(conditionalTypeSimplification.ts, 3, 5))
>v : Symbol(v, Decl(conditionalTypeSimplification.ts, 3, 9))
>T : Symbol(T, Decl(conditionalTypeSimplification.ts, 3, 5))
>SchemaType : Symbol(SchemaType, Decl(conditionalTypeSimplification.ts, 5, 1))
>S : Symbol(S, Decl(conditionalTypeSimplification.ts, 2, 25))
>Exclude : Symbol(Exclude, Decl(lib.es5.d.ts, --, --))
>V : Symbol(V, Decl(conditionalTypeSimplification.ts, 2, 27))
>T : Symbol(T, Decl(conditionalTypeSimplification.ts, 3, 5))

m2<T> (v: T): SchemaType<S, T>;
>m2 : Symbol(AbstractSchema.m2, Decl(conditionalTypeSimplification.ts, 3, 45))
>T : Symbol(T, Decl(conditionalTypeSimplification.ts, 4, 5))
>v : Symbol(v, Decl(conditionalTypeSimplification.ts, 4, 9))
>T : Symbol(T, Decl(conditionalTypeSimplification.ts, 4, 5))
>SchemaType : Symbol(SchemaType, Decl(conditionalTypeSimplification.ts, 5, 1))
>S : Symbol(S, Decl(conditionalTypeSimplification.ts, 2, 25))
>T : Symbol(T, Decl(conditionalTypeSimplification.ts, 4, 5))
}

type SchemaType<S, V> = S extends object ? AnySchema<V> : never;
>SchemaType : Symbol(SchemaType, Decl(conditionalTypeSimplification.ts, 5, 1))
>S : Symbol(S, Decl(conditionalTypeSimplification.ts, 7, 16))
>V : Symbol(V, Decl(conditionalTypeSimplification.ts, 7, 18))
>S : Symbol(S, Decl(conditionalTypeSimplification.ts, 7, 16))
>AnySchema : Symbol(AnySchema, Decl(conditionalTypeSimplification.ts, 7, 64))
>V : Symbol(V, Decl(conditionalTypeSimplification.ts, 7, 18))

interface AnySchema<V> extends AnySchemaType<AnySchema<undefined>, V> { }
>AnySchema : Symbol(AnySchema, Decl(conditionalTypeSimplification.ts, 7, 64))
>V : Symbol(V, Decl(conditionalTypeSimplification.ts, 8, 20))
>AnySchemaType : Symbol(AnySchemaType, Decl(conditionalTypeSimplification.ts, 8, 73))
>AnySchema : Symbol(AnySchema, Decl(conditionalTypeSimplification.ts, 7, 64))
>V : Symbol(V, Decl(conditionalTypeSimplification.ts, 8, 20))

interface AnySchemaType<S extends AbstractSchema<any, any>, V> extends AbstractSchema<S, V> { }
>AnySchemaType : Symbol(AnySchemaType, Decl(conditionalTypeSimplification.ts, 8, 73))
>S : Symbol(S, Decl(conditionalTypeSimplification.ts, 9, 24))
>AbstractSchema : Symbol(AbstractSchema, Decl(conditionalTypeSimplification.ts, 0, 0))
>V : Symbol(V, Decl(conditionalTypeSimplification.ts, 9, 59))
>AbstractSchema : Symbol(AbstractSchema, Decl(conditionalTypeSimplification.ts, 0, 0))
>S : Symbol(S, Decl(conditionalTypeSimplification.ts, 9, 24))
>V : Symbol(V, Decl(conditionalTypeSimplification.ts, 9, 59))

19 changes: 19 additions & 0 deletions tests/baselines/reference/conditionalTypeSimplification.types
Original file line number Diff line number Diff line change
@@ -0,0 +1,19 @@
=== tests/cases/compiler/conditionalTypeSimplification.ts ===
// Repro from #30794

interface AbstractSchema<S, V> {
m1<T> (v: T): SchemaType<S, Exclude<V, T>>;
>m1 : <T>(v: T) => SchemaType<S, Exclude<V, T>>
>v : T

m2<T> (v: T): SchemaType<S, T>;
>m2 : <T>(v: T) => SchemaType<S, T>
>v : T
}

type SchemaType<S, V> = S extends object ? AnySchema<V> : never;
>SchemaType : SchemaType<S, V>

interface AnySchema<V> extends AnySchemaType<AnySchema<undefined>, V> { }
interface AnySchemaType<S extends AbstractSchema<any, any>, V> extends AbstractSchema<S, V> { }

10 changes: 10 additions & 0 deletions tests/cases/compiler/conditionalTypeSimplification.ts
Original file line number Diff line number Diff line change
@@ -0,0 +1,10 @@
// Repro from #30794

interface AbstractSchema<S, V> {
m1<T> (v: T): SchemaType<S, Exclude<V, T>>;
m2<T> (v: T): SchemaType<S, T>;
}

type SchemaType<S, V> = S extends object ? AnySchema<V> : never;
interface AnySchema<V> extends AnySchemaType<AnySchema<undefined>, V> { }
interface AnySchemaType<S extends AbstractSchema<any, any>, V> extends AbstractSchema<S, V> { }