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Merged
ahejlsberg merged 4 commits into from
Aug 1, 2016
Merged

Use "best choice type" for || and ?: operators #10069

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fc85bc5
Use "best choice type" for || and ?: operators
ahejlsberg Jul 31, 2016
47f6bb2
Add test
ahejlsberg Aug 1, 2016
aa8c6c8
Add test baselines
ahejlsberg Aug 1, 2016
c7d2e59
Accept new baselines
ahejlsberg Aug 1, 2016
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12 changes: 10 additions & 2 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -12896,6 +12896,14 @@ namespace ts {
return (target.flags & TypeFlags.Nullable) !== 0 || isTypeComparableTo(source, target);
}

function getBestChoiceType(type1: Type, type2: Type): Type {
const firstAssignableToSecond = isTypeAssignableTo(type1, type2);
const secondAssignableToFirst = isTypeAssignableTo(type2, type1);
return secondAssignableToFirst && !firstAssignableToSecond ? type1 :
firstAssignableToSecond && !secondAssignableToFirst ? type2 :
getUnionType([type1, type2], /*subtypeReduction*/ true);
}

function checkBinaryExpression(node: BinaryExpression, contextualMapper?: TypeMapper) {
return checkBinaryLikeExpression(node.left, node.operatorToken, node.right, contextualMapper, node);
}
Expand Down Expand Up @@ -13039,7 +13047,7 @@ namespace ts {
leftType;
case SyntaxKind.BarBarToken:
return getTypeFacts(leftType) & TypeFacts.Falsy ?
getUnionType([removeDefinitelyFalsyTypes(leftType), rightType], /*subtypeReduction*/ true) :
getBestChoiceType(removeDefinitelyFalsyTypes(leftType), rightType) :
leftType;
case SyntaxKind.EqualsToken:
checkAssignmentOperator(rightType);
Expand Down Expand Up @@ -13166,7 +13174,7 @@ namespace ts {
checkExpression(node.condition);
const type1 = checkExpression(node.whenTrue, contextualMapper);
const type2 = checkExpression(node.whenFalse, contextualMapper);
return getUnionType([type1, type2], /*subtypeReduction*/ true);
return getBestChoiceType(type1, type2);
}

function typeContainsLiteralFromEnum(type: Type, enumType: EnumType) {
Expand Down
35 changes: 35 additions & 0 deletions tests/baselines/reference/bestChoiceType.js
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@@ -0,0 +1,35 @@
//// [bestChoiceType.ts]

// Repro from #10041

(''.match(/ /) || []).map(s => s.toLowerCase());

// Similar cases

function f1() {
let x = ''.match(/ /);
let y = x || [];
let z = y.map(s => s.toLowerCase());
}

function f2() {
let x = ''.match(/ /);
let y = x ? x : [];
let z = y.map(s => s.toLowerCase());
}


//// [bestChoiceType.js]
// Repro from #10041
(''.match(/ /) || []).map(function (s) { return s.toLowerCase(); });
// Similar cases
function f1() {
var x = ''.match(/ /);
var y = x || [];
var z = y.map(function (s) { return s.toLowerCase(); });
}
function f2() {
var x = ''.match(/ /);
var y = x ? x : [];
var z = y.map(function (s) { return s.toLowerCase(); });
}
63 changes: 63 additions & 0 deletions tests/baselines/reference/bestChoiceType.symbols
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@@ -0,0 +1,63 @@
=== tests/cases/compiler/bestChoiceType.ts ===

// Repro from #10041

(''.match(/ /) || []).map(s => s.toLowerCase());
>(''.match(/ /) || []).map : Symbol(Array.map, Decl(lib.d.ts, --, --))
>''.match : Symbol(String.match, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
>match : Symbol(String.match, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
>map : Symbol(Array.map, Decl(lib.d.ts, --, --))
>s : Symbol(s, Decl(bestChoiceType.ts, 3, 26))
>s.toLowerCase : Symbol(String.toLowerCase, Decl(lib.d.ts, --, --))
>s : Symbol(s, Decl(bestChoiceType.ts, 3, 26))
>toLowerCase : Symbol(String.toLowerCase, Decl(lib.d.ts, --, --))

// Similar cases

function f1() {
>f1 : Symbol(f1, Decl(bestChoiceType.ts, 3, 48))

let x = ''.match(/ /);
>x : Symbol(x, Decl(bestChoiceType.ts, 8, 7))
>''.match : Symbol(String.match, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
>match : Symbol(String.match, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))

let y = x || [];
>y : Symbol(y, Decl(bestChoiceType.ts, 9, 7))
>x : Symbol(x, Decl(bestChoiceType.ts, 8, 7))

let z = y.map(s => s.toLowerCase());
>z : Symbol(z, Decl(bestChoiceType.ts, 10, 7))
>y.map : Symbol(Array.map, Decl(lib.d.ts, --, --))
>y : Symbol(y, Decl(bestChoiceType.ts, 9, 7))
>map : Symbol(Array.map, Decl(lib.d.ts, --, --))
>s : Symbol(s, Decl(bestChoiceType.ts, 10, 18))
>s.toLowerCase : Symbol(String.toLowerCase, Decl(lib.d.ts, --, --))
>s : Symbol(s, Decl(bestChoiceType.ts, 10, 18))
>toLowerCase : Symbol(String.toLowerCase, Decl(lib.d.ts, --, --))
}

function f2() {
>f2 : Symbol(f2, Decl(bestChoiceType.ts, 11, 1))

let x = ''.match(/ /);
>x : Symbol(x, Decl(bestChoiceType.ts, 14, 7))
>''.match : Symbol(String.match, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
>match : Symbol(String.match, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))

let y = x ? x : [];
>y : Symbol(y, Decl(bestChoiceType.ts, 15, 7))
>x : Symbol(x, Decl(bestChoiceType.ts, 14, 7))
>x : Symbol(x, Decl(bestChoiceType.ts, 14, 7))

let z = y.map(s => s.toLowerCase());
>z : Symbol(z, Decl(bestChoiceType.ts, 16, 7))
>y.map : Symbol(Array.map, Decl(lib.d.ts, --, --))
>y : Symbol(y, Decl(bestChoiceType.ts, 15, 7))
>map : Symbol(Array.map, Decl(lib.d.ts, --, --))
>s : Symbol(s, Decl(bestChoiceType.ts, 16, 18))
>s.toLowerCase : Symbol(String.toLowerCase, Decl(lib.d.ts, --, --))
>s : Symbol(s, Decl(bestChoiceType.ts, 16, 18))
>toLowerCase : Symbol(String.toLowerCase, Decl(lib.d.ts, --, --))
}

88 changes: 88 additions & 0 deletions tests/baselines/reference/bestChoiceType.types
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@@ -0,0 +1,88 @@
=== tests/cases/compiler/bestChoiceType.ts ===

// Repro from #10041

(''.match(/ /) || []).map(s => s.toLowerCase());
>(''.match(/ /) || []).map(s => s.toLowerCase()) : string[]
>(''.match(/ /) || []).map : <U>(callbackfn: (value: string, index: number, array: string[]) => U, thisArg?: any) => U[]
>(''.match(/ /) || []) : RegExpMatchArray
>''.match(/ /) || [] : RegExpMatchArray
>''.match(/ /) : RegExpMatchArray | null
>''.match : { (regexp: string): RegExpMatchArray | null; (regexp: RegExp): RegExpMatchArray | null; }
>'' : string
>match : { (regexp: string): RegExpMatchArray | null; (regexp: RegExp): RegExpMatchArray | null; }
>/ / : RegExp
>[] : never[]
>map : <U>(callbackfn: (value: string, index: number, array: string[]) => U, thisArg?: any) => U[]
>s => s.toLowerCase() : (s: string) => string
>s : string
>s.toLowerCase() : string
>s.toLowerCase : () => string
>s : string
>toLowerCase : () => string

// Similar cases

function f1() {
>f1 : () => void

let x = ''.match(/ /);
>x : RegExpMatchArray | null
>''.match(/ /) : RegExpMatchArray | null
>''.match : { (regexp: string): RegExpMatchArray | null; (regexp: RegExp): RegExpMatchArray | null; }
>'' : string
>match : { (regexp: string): RegExpMatchArray | null; (regexp: RegExp): RegExpMatchArray | null; }
>/ / : RegExp

let y = x || [];
>y : RegExpMatchArray
>x || [] : RegExpMatchArray
>x : RegExpMatchArray | null
>[] : never[]

let z = y.map(s => s.toLowerCase());
>z : string[]
>y.map(s => s.toLowerCase()) : string[]
>y.map : <U>(callbackfn: (value: string, index: number, array: string[]) => U, thisArg?: any) => U[]
>y : RegExpMatchArray
>map : <U>(callbackfn: (value: string, index: number, array: string[]) => U, thisArg?: any) => U[]
>s => s.toLowerCase() : (s: string) => string
>s : string
>s.toLowerCase() : string
>s.toLowerCase : () => string
>s : string
>toLowerCase : () => string
}

function f2() {
>f2 : () => void

let x = ''.match(/ /);
>x : RegExpMatchArray | null
>''.match(/ /) : RegExpMatchArray | null
>''.match : { (regexp: string): RegExpMatchArray | null; (regexp: RegExp): RegExpMatchArray | null; }
>'' : string
>match : { (regexp: string): RegExpMatchArray | null; (regexp: RegExp): RegExpMatchArray | null; }
>/ / : RegExp

let y = x ? x : [];
>y : RegExpMatchArray
>x ? x : [] : RegExpMatchArray
>x : RegExpMatchArray | null
>x : RegExpMatchArray
>[] : never[]

let z = y.map(s => s.toLowerCase());
>z : string[]
>y.map(s => s.toLowerCase()) : string[]
>y.map : <U>(callbackfn: (value: string, index: number, array: string[]) => U, thisArg?: any) => U[]
>y : RegExpMatchArray
>map : <U>(callbackfn: (value: string, index: number, array: string[]) => U, thisArg?: any) => U[]
>s => s.toLowerCase() : (s: string) => string
>s : string
>s.toLowerCase() : string
>s.toLowerCase : () => string
>s : string
>toLowerCase : () => string
}

4 changes: 2 additions & 2 deletions tests/baselines/reference/nonContextuallyTypedLogicalOr.symbols
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Expand Up @@ -28,8 +28,8 @@ var e: Ellement;
>Ellement : Symbol(Ellement, Decl(nonContextuallyTypedLogicalOr.ts, 3, 1))

(c || e).dummy;
>(c || e).dummy : Symbol(dummy, Decl(nonContextuallyTypedLogicalOr.ts, 0, 22), Decl(nonContextuallyTypedLogicalOr.ts, 5, 20))
>(c || e).dummy : Symbol(Contextual.dummy, Decl(nonContextuallyTypedLogicalOr.ts, 0, 22))
>c : Symbol(c, Decl(nonContextuallyTypedLogicalOr.ts, 10, 3))
>e : Symbol(e, Decl(nonContextuallyTypedLogicalOr.ts, 11, 3))
>dummy : Symbol(dummy, Decl(nonContextuallyTypedLogicalOr.ts, 0, 22), Decl(nonContextuallyTypedLogicalOr.ts, 5, 20))
>dummy : Symbol(Contextual.dummy, Decl(nonContextuallyTypedLogicalOr.ts, 0, 22))

4 changes: 2 additions & 2 deletions tests/baselines/reference/nonContextuallyTypedLogicalOr.types
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Expand Up @@ -29,8 +29,8 @@ var e: Ellement;

(c || e).dummy;
>(c || e).dummy : any
>(c || e) : Contextual | Ellement
>c || e : Contextual | Ellement
>(c || e) : Contextual
>c || e : Contextual
>c : Contextual
>e : Ellement
>dummy : any
Expand Down
4 changes: 2 additions & 2 deletions tests/baselines/reference/subtypingWithObjectMembersOptionality3.types
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Expand Up @@ -69,8 +69,8 @@ var b: { Foo2: Derived; }
>Derived : Derived

var r = true ? a : b; // ok
>r : { Foo?: Base; } | { Foo2: Derived; }
>true ? a : b : { Foo?: Base; } | { Foo2: Derived; }
>r : { Foo?: Base; }
>true ? a : b : { Foo?: Base; }
>true : boolean
>a : { Foo?: Base; }
>b : { Foo2: Derived; }
Expand Down
4 changes: 2 additions & 2 deletions tests/baselines/reference/subtypingWithObjectMembersOptionality4.types
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Expand Up @@ -69,8 +69,8 @@ var b: { Foo2?: Derived; }
>Derived : Derived

var r = true ? a : b; // ok
>r : { Foo: Base; } | { Foo2?: Derived; }
>true ? a : b : { Foo: Base; } | { Foo2?: Derived; }
>r : { Foo2?: Derived; }
>true ? a : b : { Foo2?: Derived; }
>true : boolean
>a : { Foo: Base; }
>b : { Foo2?: Derived; }
Expand Down
19 changes: 19 additions & 0 deletions tests/cases/compiler/bestChoiceType.ts
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@@ -0,0 +1,19 @@
// @strictNullChecks: true

// Repro from #10041

(''.match(/ /) || []).map(s => s.toLowerCase());

// Similar cases

function f1() {
let x = ''.match(/ /);
let y = x || [];
let z = y.map(s => s.toLowerCase());
}

function f2() {
let x = ''.match(/ /);
let y = x ? x : [];
let z = y.map(s => s.toLowerCase());
}