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Additional tweak to mapped type property modifier propagation #12843

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Merged
merged 3 commits into from
Dec 12, 2016
Merged

Additional tweak to mapped type property modifier propagation #12843

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5229176
Additional tweak to mapped type property modifier propagation
ahejlsberg Dec 12, 2016
cedc53e
Add more tests
ahejlsberg Dec 12, 2016
4898b9e
Accept new baselines
ahejlsberg Dec 12, 2016
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22 changes: 16 additions & 6 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -4577,12 +4577,22 @@ namespace ts {

function getModifiersTypeFromMappedType(type: MappedType) {
if (!type.modifiersType) {
// If the mapped type was declared as { [P in keyof T]: X } or as { [P in K]: X }, where
// K is constrained to 'K extends keyof T', then we will copy property modifiers from T.
const declaredType = <MappedType>getTypeFromMappedTypeNode(type.declaration);
const constraint = getConstraintTypeFromMappedType(declaredType);
const extendedConstraint = constraint.flags & TypeFlags.TypeParameter ? getConstraintOfTypeParameter(<TypeParameter>constraint) : constraint;
type.modifiersType = extendedConstraint.flags & TypeFlags.Index ? instantiateType((<IndexType>extendedConstraint).type, type.mapper || identityMapper) : emptyObjectType;
const constraintDeclaration = type.declaration.typeParameter.constraint;
if (constraintDeclaration.kind === SyntaxKind.TypeOperator) {
// If the constraint declaration is a 'keyof T' node, the modifiers type is T. We check
// AST nodes here because, when T is a non-generic type, the logic below eagerly resolves
// 'keyof T' to a literal union type and we can't recover T from that type.
type.modifiersType = instantiateType(getTypeFromTypeNode((<TypeOperatorNode>constraintDeclaration).type), type.mapper || identityMapper);
}
else {
// Otherwise, get the declared constraint type, and if the constraint type is a type parameter,
// get the constraint of that type parameter. If the resulting type is an indexed type 'keyof T',
// the modifiers type is T. Otherwise, the modifiers type is {}.
const declaredType = <MappedType>getTypeFromMappedTypeNode(type.declaration);
const constraint = getConstraintTypeFromMappedType(declaredType);
const extendedConstraint = constraint.flags & TypeFlags.TypeParameter ? getConstraintOfTypeParameter(<TypeParameter>constraint) : constraint;
type.modifiersType = extendedConstraint.flags & TypeFlags.Index ? instantiateType((<IndexType>extendedConstraint).type, type.mapper || identityMapper) : emptyObjectType;
}
}
return type.modifiersType;
}
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22 changes: 17 additions & 5 deletions tests/baselines/reference/mappedTypeModifiers.js
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Original file line number Diff line number Diff line change
Expand Up @@ -19,19 +19,22 @@ var v01: Pick<Pick<T, keyof T>, keyof T>;
var v02: TP;
var v02: { [P in keyof T]?: T[P] };
var v02: Partial<T>;
var v02: Pick<TP, keyof T>;
var v02: { [P in keyof TP]: TP[P] }
var v02: Pick<TP, keyof TP>;

var v03: TR;
var v03: { readonly [P in keyof T]: T[P] };
var v03: Readonly<T>;
var v03: Pick<TR, keyof T>;
var v03: { [P in keyof TR]: TR[P] }
var v03: Pick<TR, keyof TR>;

var v04: TPR;
var v04: { readonly [P in keyof T]?: T[P] };
var v04: Partial<TR>;
var v04: Readonly<TP>;
var v04: Partial<Readonly<T>>;
var v04: Readonly<Partial<T>>;
var v04: { [P in keyof TPR]: TPR[P] }
var v04: Pick<TPR, keyof T>;

type Boxified<T> = { [P in keyof T]: { x: T[P] } };
Expand All @@ -55,20 +58,23 @@ var b01: Pick<Pick<B, keyof B>, keyof B>;
var b02: BP;
var b02: { [P in keyof B]?: B[P] };
var b02: Partial<B>;
var b02: Pick<BP, keyof B>;
var b02: { [P in keyof BP]: BP[P] }
var b02: Pick<BP, keyof BP>;

var b03: BR;
var b03: { readonly [P in keyof B]: B[P] };
var b03: Readonly<B>;
var b03: Pick<BR, keyof B>;
var b03: { [P in keyof BR]: BR[P] }
var b03: Pick<BR, keyof BR>;

var b04: BPR;
var b04: { readonly [P in keyof B]?: B[P] };
var b04: Partial<BR>;
var b04: Readonly<BP>;
var b04: Partial<Readonly<B>>;
var b04: Readonly<Partial<B>>;
var b04: Pick<BPR, keyof B>;
var b04: { [P in keyof BPR]: BPR[P] }
var b04: Pick<BPR, keyof BPR>;

//// [mappedTypeModifiers.js]
var v00;
Expand All @@ -84,6 +90,8 @@ var v02;
var v02;
var v02;
var v02;
var v02;
var v03;
var v03;
var v03;
var v03;
Expand All @@ -95,6 +103,7 @@ var v04;
var v04;
var v04;
var v04;
var v04;
var b00;
var b00;
var b00;
Expand All @@ -108,6 +117,8 @@ var b02;
var b02;
var b02;
var b02;
var b02;
var b03;
var b03;
var b03;
var b03;
Expand All @@ -119,3 +130,4 @@ var b04;
var b04;
var b04;
var b04;
var b04;
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