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Merged
merged 4 commits into from
Sep 21, 2019
Merged

Less aggressive contextual signature instantiation #33228

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8ffc42f
Don't instantiate-in-context-of when inferring to type variable
ahejlsberg Sep 3, 2019
c02fdaa
Accept new baselines
ahejlsberg Sep 3, 2019
4bd9b62
Add regression tests
ahejlsberg Sep 4, 2019
bbec8b3
Accept new baselines
ahejlsberg Sep 4, 2019
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7 changes: 4 additions & 3 deletions src/compiler/checker.ts
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Expand Up @@ -177,6 +177,7 @@ namespace ts {
const enum ContextFlags {
None = 0,
Signature = 1 << 0, // Obtaining contextual signature
NoConstraints = 1 << 1, // Don't obtain type variable constraints
}

const enum AccessFlags {
Expand Down Expand Up @@ -19193,7 +19194,7 @@ namespace ts {
getContextualTypeForObjectLiteralMethod(node, contextFlags) :
getContextualType(node, contextFlags);
const instantiatedType = instantiateContextualType(contextualType, node, contextFlags);
if (instantiatedType) {
if (instantiatedType && !(contextFlags && contextFlags & ContextFlags.NoConstraints && instantiatedType.flags & TypeFlags.TypeVariable)) {
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In addition to TypeVariable, should this also be looking for Substitution (since that wraps a type variable pretty directly)?

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Can you write an example that would depend on this?

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declare function foo<T extends (x: string) => string>(f: T): T;

type SubstituteOf<T> = T extends {} ? T : never;

const f = foo(<U>(x: SubstituteOf<U>) => x);  // <U>(x: U) => U

still instantiates as string on this PR.

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No, for your example you get what you'd expect with the PR:

const f = foo(<U>(x: SubstituteOf<U>) => x);  // <U>(x: SubstituteOf<U>) => SubstituteOf<U>

The substitution type would need to be in the contextual type (i.e. the parameter's type would need to be a substitution type) for the original question you posed to make sense. I don't see how that could happen which is why I asked for an example.

const apparentType = mapType(instantiatedType, getApparentType, /*noReductions*/ true);
if (apparentType.flags & TypeFlags.Union) {
if (isObjectLiteralExpression(node)) {
Expand Down Expand Up @@ -25098,8 +25099,8 @@ namespace ts {
const constructSignature = getSingleSignature(type, SignatureKind.Construct, /*allowMembers*/ true);
const signature = callSignature || constructSignature;
if (signature && signature.typeParameters) {
const contextualType = getApparentTypeOfContextualType(<Expression>node);
if (contextualType && !isMixinConstructorType(contextualType)) {
const contextualType = getApparentTypeOfContextualType(<Expression>node, ContextFlags.NoConstraints);
if (contextualType) {
const contextualSignature = getSingleSignature(getNonNullableType(contextualType), callSignature ? SignatureKind.Call : SignatureKind.Construct, /*allowMembers*/ false);
if (contextualSignature && !contextualSignature.typeParameters) {
if (checkMode & CheckMode.SkipGenericFunctions) {
Expand Down
29 changes: 29 additions & 0 deletions tests/baselines/reference/contextualSignatureInstantiation4.js
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@@ -0,0 +1,29 @@
//// [contextualSignatureInstantiation4.ts]
// Repros from #32976

declare class Banana<T extends string> { constructor(a: string, property: T) }

declare function fruitFactory1<TFruit>(Fruit: new (...args: any[]) => TFruit): TFruit
const banana1 = fruitFactory1(Banana) // Banana<any>

declare function fruitFactory2<TFruit>(Fruit: new (a: string, ...args: any[]) => TFruit): TFruit
const banana2 = fruitFactory2(Banana) // Banana<any>

declare function fruitFactory3<TFruit>(Fruit: new (a: string, s: "foo", ...args: any[]) => TFruit): TFruit
const banana3 = fruitFactory3(Banana) // Banana<"foo">

declare function fruitFactory4<TFruit>(Fruit: new (a: string, ...args: "foo"[]) => TFruit): TFruit
const banana4 = fruitFactory4(Banana) // Banana<"foo">

declare function fruitFactory5<TFruit>(Fruit: new (...args: "foo"[]) => TFruit): TFruit
const banana5 = fruitFactory5(Banana) // Banana<"foo">


//// [contextualSignatureInstantiation4.js]
"use strict";
// Repros from #32976
var banana1 = fruitFactory1(Banana); // Banana<any>
var banana2 = fruitFactory2(Banana); // Banana<any>
var banana3 = fruitFactory3(Banana); // Banana<"foo">
var banana4 = fruitFactory4(Banana); // Banana<"foo">
var banana5 = fruitFactory5(Banana); // Banana<"foo">
79 changes: 79 additions & 0 deletions tests/baselines/reference/contextualSignatureInstantiation4.symbols
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=== tests/cases/compiler/contextualSignatureInstantiation4.ts ===
// Repros from #32976

declare class Banana<T extends string> { constructor(a: string, property: T) }
>Banana : Symbol(Banana, Decl(contextualSignatureInstantiation4.ts, 0, 0))
>T : Symbol(T, Decl(contextualSignatureInstantiation4.ts, 2, 21))
>a : Symbol(a, Decl(contextualSignatureInstantiation4.ts, 2, 53))
>property : Symbol(property, Decl(contextualSignatureInstantiation4.ts, 2, 63))
>T : Symbol(T, Decl(contextualSignatureInstantiation4.ts, 2, 21))

declare function fruitFactory1<TFruit>(Fruit: new (...args: any[]) => TFruit): TFruit
>fruitFactory1 : Symbol(fruitFactory1, Decl(contextualSignatureInstantiation4.ts, 2, 78))
>TFruit : Symbol(TFruit, Decl(contextualSignatureInstantiation4.ts, 4, 31))
>Fruit : Symbol(Fruit, Decl(contextualSignatureInstantiation4.ts, 4, 39))
>args : Symbol(args, Decl(contextualSignatureInstantiation4.ts, 4, 51))
>TFruit : Symbol(TFruit, Decl(contextualSignatureInstantiation4.ts, 4, 31))
>TFruit : Symbol(TFruit, Decl(contextualSignatureInstantiation4.ts, 4, 31))

const banana1 = fruitFactory1(Banana) // Banana<any>
>banana1 : Symbol(banana1, Decl(contextualSignatureInstantiation4.ts, 5, 5))
>fruitFactory1 : Symbol(fruitFactory1, Decl(contextualSignatureInstantiation4.ts, 2, 78))
>Banana : Symbol(Banana, Decl(contextualSignatureInstantiation4.ts, 0, 0))

declare function fruitFactory2<TFruit>(Fruit: new (a: string, ...args: any[]) => TFruit): TFruit
>fruitFactory2 : Symbol(fruitFactory2, Decl(contextualSignatureInstantiation4.ts, 5, 37))
>TFruit : Symbol(TFruit, Decl(contextualSignatureInstantiation4.ts, 7, 31))
>Fruit : Symbol(Fruit, Decl(contextualSignatureInstantiation4.ts, 7, 39))
>a : Symbol(a, Decl(contextualSignatureInstantiation4.ts, 7, 51))
>args : Symbol(args, Decl(contextualSignatureInstantiation4.ts, 7, 61))
>TFruit : Symbol(TFruit, Decl(contextualSignatureInstantiation4.ts, 7, 31))
>TFruit : Symbol(TFruit, Decl(contextualSignatureInstantiation4.ts, 7, 31))

const banana2 = fruitFactory2(Banana) // Banana<any>
>banana2 : Symbol(banana2, Decl(contextualSignatureInstantiation4.ts, 8, 5))
>fruitFactory2 : Symbol(fruitFactory2, Decl(contextualSignatureInstantiation4.ts, 5, 37))
>Banana : Symbol(Banana, Decl(contextualSignatureInstantiation4.ts, 0, 0))

declare function fruitFactory3<TFruit>(Fruit: new (a: string, s: "foo", ...args: any[]) => TFruit): TFruit
>fruitFactory3 : Symbol(fruitFactory3, Decl(contextualSignatureInstantiation4.ts, 8, 37))
>TFruit : Symbol(TFruit, Decl(contextualSignatureInstantiation4.ts, 10, 31))
>Fruit : Symbol(Fruit, Decl(contextualSignatureInstantiation4.ts, 10, 39))
>a : Symbol(a, Decl(contextualSignatureInstantiation4.ts, 10, 51))
>s : Symbol(s, Decl(contextualSignatureInstantiation4.ts, 10, 61))
>args : Symbol(args, Decl(contextualSignatureInstantiation4.ts, 10, 71))
>TFruit : Symbol(TFruit, Decl(contextualSignatureInstantiation4.ts, 10, 31))
>TFruit : Symbol(TFruit, Decl(contextualSignatureInstantiation4.ts, 10, 31))

const banana3 = fruitFactory3(Banana) // Banana<"foo">
>banana3 : Symbol(banana3, Decl(contextualSignatureInstantiation4.ts, 11, 5))
>fruitFactory3 : Symbol(fruitFactory3, Decl(contextualSignatureInstantiation4.ts, 8, 37))
>Banana : Symbol(Banana, Decl(contextualSignatureInstantiation4.ts, 0, 0))

declare function fruitFactory4<TFruit>(Fruit: new (a: string, ...args: "foo"[]) => TFruit): TFruit
>fruitFactory4 : Symbol(fruitFactory4, Decl(contextualSignatureInstantiation4.ts, 11, 37))
>TFruit : Symbol(TFruit, Decl(contextualSignatureInstantiation4.ts, 13, 31))
>Fruit : Symbol(Fruit, Decl(contextualSignatureInstantiation4.ts, 13, 39))
>a : Symbol(a, Decl(contextualSignatureInstantiation4.ts, 13, 51))
>args : Symbol(args, Decl(contextualSignatureInstantiation4.ts, 13, 61))
>TFruit : Symbol(TFruit, Decl(contextualSignatureInstantiation4.ts, 13, 31))
>TFruit : Symbol(TFruit, Decl(contextualSignatureInstantiation4.ts, 13, 31))

const banana4 = fruitFactory4(Banana) // Banana<"foo">
>banana4 : Symbol(banana4, Decl(contextualSignatureInstantiation4.ts, 14, 5))
>fruitFactory4 : Symbol(fruitFactory4, Decl(contextualSignatureInstantiation4.ts, 11, 37))
>Banana : Symbol(Banana, Decl(contextualSignatureInstantiation4.ts, 0, 0))

declare function fruitFactory5<TFruit>(Fruit: new (...args: "foo"[]) => TFruit): TFruit
>fruitFactory5 : Symbol(fruitFactory5, Decl(contextualSignatureInstantiation4.ts, 14, 37))
>TFruit : Symbol(TFruit, Decl(contextualSignatureInstantiation4.ts, 16, 31))
>Fruit : Symbol(Fruit, Decl(contextualSignatureInstantiation4.ts, 16, 39))
>args : Symbol(args, Decl(contextualSignatureInstantiation4.ts, 16, 51))
>TFruit : Symbol(TFruit, Decl(contextualSignatureInstantiation4.ts, 16, 31))
>TFruit : Symbol(TFruit, Decl(contextualSignatureInstantiation4.ts, 16, 31))

const banana5 = fruitFactory5(Banana) // Banana<"foo">
>banana5 : Symbol(banana5, Decl(contextualSignatureInstantiation4.ts, 17, 5))
>fruitFactory5 : Symbol(fruitFactory5, Decl(contextualSignatureInstantiation4.ts, 14, 37))
>Banana : Symbol(Banana, Decl(contextualSignatureInstantiation4.ts, 0, 0))

67 changes: 67 additions & 0 deletions tests/baselines/reference/contextualSignatureInstantiation4.types
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=== tests/cases/compiler/contextualSignatureInstantiation4.ts ===
// Repros from #32976

declare class Banana<T extends string> { constructor(a: string, property: T) }
>Banana : Banana<T>
>a : string
>property : T

declare function fruitFactory1<TFruit>(Fruit: new (...args: any[]) => TFruit): TFruit
>fruitFactory1 : <TFruit>(Fruit: new (...args: any[]) => TFruit) => TFruit
>Fruit : new (...args: any[]) => TFruit
>args : any[]

const banana1 = fruitFactory1(Banana) // Banana<any>
>banana1 : Banana<any>
>fruitFactory1(Banana) : Banana<any>
>fruitFactory1 : <TFruit>(Fruit: new (...args: any[]) => TFruit) => TFruit
>Banana : typeof Banana

declare function fruitFactory2<TFruit>(Fruit: new (a: string, ...args: any[]) => TFruit): TFruit
>fruitFactory2 : <TFruit>(Fruit: new (a: string, ...args: any[]) => TFruit) => TFruit
>Fruit : new (a: string, ...args: any[]) => TFruit
>a : string
>args : any[]

const banana2 = fruitFactory2(Banana) // Banana<any>
>banana2 : Banana<any>
>fruitFactory2(Banana) : Banana<any>
>fruitFactory2 : <TFruit>(Fruit: new (a: string, ...args: any[]) => TFruit) => TFruit
>Banana : typeof Banana

declare function fruitFactory3<TFruit>(Fruit: new (a: string, s: "foo", ...args: any[]) => TFruit): TFruit
>fruitFactory3 : <TFruit>(Fruit: new (a: string, s: "foo", ...args: any[]) => TFruit) => TFruit
>Fruit : new (a: string, s: "foo", ...args: any[]) => TFruit
>a : string
>s : "foo"
>args : any[]

const banana3 = fruitFactory3(Banana) // Banana<"foo">
>banana3 : Banana<"foo">
>fruitFactory3(Banana) : Banana<"foo">
>fruitFactory3 : <TFruit>(Fruit: new (a: string, s: "foo", ...args: any[]) => TFruit) => TFruit
>Banana : typeof Banana

declare function fruitFactory4<TFruit>(Fruit: new (a: string, ...args: "foo"[]) => TFruit): TFruit
>fruitFactory4 : <TFruit>(Fruit: new (a: string, ...args: "foo"[]) => TFruit) => TFruit
>Fruit : new (a: string, ...args: "foo"[]) => TFruit
>a : string
>args : "foo"[]

const banana4 = fruitFactory4(Banana) // Banana<"foo">
>banana4 : Banana<"foo">
>fruitFactory4(Banana) : Banana<"foo">
>fruitFactory4 : <TFruit>(Fruit: new (a: string, ...args: "foo"[]) => TFruit) => TFruit
>Banana : typeof Banana

declare function fruitFactory5<TFruit>(Fruit: new (...args: "foo"[]) => TFruit): TFruit
>fruitFactory5 : <TFruit>(Fruit: new (...args: "foo"[]) => TFruit) => TFruit
>Fruit : new (...args: "foo"[]) => TFruit
>args : "foo"[]

const banana5 = fruitFactory5(Banana) // Banana<"foo">
>banana5 : Banana<"foo">
>fruitFactory5(Banana) : Banana<"foo">
>fruitFactory5 : <TFruit>(Fruit: new (...args: "foo"[]) => TFruit) => TFruit
>Banana : typeof Banana

4 changes: 2 additions & 2 deletions tests/baselines/reference/functionConstraintSatisfaction2.types
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Expand Up @@ -79,8 +79,8 @@ var r7 = foo2(b);
>b : new (x: string) => string

var r8 = foo2(<U>(x: U) => x); // no error expected
>r8 : (x: string) => string
>foo2(<U>(x: U) => x) : (x: string) => string
>r8 : <U>(x: U) => U
>foo2(<U>(x: U) => x) : <U>(x: U) => U
>foo2 : <T extends (x: string) => string>(x: T) => T
><U>(x: U) => x : <U>(x: U) => U
>x : U
Expand Down
8 changes: 4 additions & 4 deletions tests/baselines/reference/functionConstraintSatisfaction3.types
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Expand Up @@ -103,16 +103,16 @@ var c2: { <T>(x: T): T; <T>(x: T, y: T): T };
>y : T

var r9 = foo(function <U>(x: U) { return x; });
>r9 : (x: string) => string
>foo(function <U>(x: U) { return x; }) : (x: string) => string
>r9 : <U>(x: U) => U
>foo(function <U>(x: U) { return x; }) : <U>(x: U) => U
>foo : <T extends (x: string) => string>(x: T) => T
>function <U>(x: U) { return x; } : <U>(x: U) => U
>x : U
>x : U

var r10 = foo(<U extends string>(x: U) => x);
>r10 : (x: string) => string
>foo(<U extends string>(x: U) => x) : (x: string) => string
>r10 : <U extends string>(x: U) => U
>foo(<U extends string>(x: U) => x) : <U extends string>(x: U) => U
>foo : <T extends (x: string) => string>(x: T) => T
><U extends string>(x: U) => x : <U extends string>(x: U) => U
>x : U
Expand Down
20 changes: 20 additions & 0 deletions tests/cases/compiler/contextualSignatureInstantiation4.ts
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@@ -0,0 +1,20 @@
// @strict: true

// Repros from #32976

declare class Banana<T extends string> { constructor(a: string, property: T) }

declare function fruitFactory1<TFruit>(Fruit: new (...args: any[]) => TFruit): TFruit
const banana1 = fruitFactory1(Banana) // Banana<any>

declare function fruitFactory2<TFruit>(Fruit: new (a: string, ...args: any[]) => TFruit): TFruit
const banana2 = fruitFactory2(Banana) // Banana<any>

declare function fruitFactory3<TFruit>(Fruit: new (a: string, s: "foo", ...args: any[]) => TFruit): TFruit
const banana3 = fruitFactory3(Banana) // Banana<"foo">

declare function fruitFactory4<TFruit>(Fruit: new (a: string, ...args: "foo"[]) => TFruit): TFruit
const banana4 = fruitFactory4(Banana) // Banana<"foo">

declare function fruitFactory5<TFruit>(Fruit: new (...args: "foo"[]) => TFruit): TFruit
const banana5 = fruitFactory5(Banana) // Banana<"foo">