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Merge pull request microsoft#3239 from Microsoft/cyclicTypeInstantiation
Detect cycles during type instantiation
2 parents 2859ccb + ebcdd85 commit 8918c8a

6 files changed

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‎src/compiler/checker.ts‎

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@@ -3866,6 +3866,18 @@ module ts {
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}
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function instantiateAnonymousType(type: ObjectType, mapper: TypeMapper): ObjectType {
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// If this type has already been instantiated using this mapper, returned the cached result. This guards against
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// infinite instantiations of cyclic types, e.g. "var x: { a: T, b: typeof x };"
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if (mapper.mappings) {
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let cached = <ObjectType>mapper.mappings[type.id];
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if (cached) {
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return cached;
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}
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}
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else {
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mapper.mappings = {};
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}
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// Instantiate the given type using the given mapper and cache the result
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let result = <ResolvedType>createObjectType(TypeFlags.Anonymous, type.symbol);
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result.properties = instantiateList(getPropertiesOfObjectType(type), mapper, instantiateSymbol);
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result.members = createSymbolTable(result.properties);
@@ -3875,6 +3887,7 @@ module ts {
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let numberIndexType = getIndexTypeOfType(type, IndexKind.Number);
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if (stringIndexType) result.stringIndexType = instantiateType(stringIndexType, mapper);
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if (numberIndexType) result.numberIndexType = instantiateType(numberIndexType, mapper);
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mapper.mappings[type.id] = result;
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return result;
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}
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‎src/compiler/types.ts‎

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@@ -1589,6 +1589,7 @@ module ts {
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/* @internal */
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export interface TypeMapper {
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(t: TypeParameter): Type;
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mappings?: Map<Type>; // Type mapping cache
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}
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/* @internal */

‎tests/baselines/reference/cyclicTypeInstantiation.js‎

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//// [cyclicTypeInstantiation.ts]
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function foo<T>() {
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var x: {
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a: T;
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b: typeof x;
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};
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return x;
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}
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function bar<T>() {
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var x: {
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a: T;
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b: typeof x;
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};
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return x;
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}
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var a = foo<string>();
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var b = bar<string>();
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// Relating types of a and b produces instantiations of the cyclic anonymous types in foo and bar
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a = b;
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//// [cyclicTypeInstantiation.js]
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function foo() {
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var x;
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return x;
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}
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function bar() {
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var x;
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return x;
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}
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var a = foo();
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var b = bar();
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// Relating types of a and b produces instantiations of the cyclic anonymous types in foo and bar
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a = b;

‎tests/baselines/reference/cyclicTypeInstantiation.symbols‎

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=== tests/cases/compiler/cyclicTypeInstantiation.ts ===
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function foo<T>() {
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>foo : Symbol(foo, Decl(cyclicTypeInstantiation.ts, 0, 0))
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>T : Symbol(T, Decl(cyclicTypeInstantiation.ts, 0, 13))
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var x: {
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>x : Symbol(x, Decl(cyclicTypeInstantiation.ts, 1, 7))
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a: T;
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>a : Symbol(a, Decl(cyclicTypeInstantiation.ts, 1, 12))
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>T : Symbol(T, Decl(cyclicTypeInstantiation.ts, 0, 13))
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b: typeof x;
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>b : Symbol(b, Decl(cyclicTypeInstantiation.ts, 2, 13))
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>x : Symbol(x, Decl(cyclicTypeInstantiation.ts, 1, 7))
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};
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return x;
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>x : Symbol(x, Decl(cyclicTypeInstantiation.ts, 1, 7))
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}
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function bar<T>() {
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>bar : Symbol(bar, Decl(cyclicTypeInstantiation.ts, 6, 1))
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>T : Symbol(T, Decl(cyclicTypeInstantiation.ts, 8, 13))
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var x: {
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>x : Symbol(x, Decl(cyclicTypeInstantiation.ts, 9, 7))
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a: T;
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>a : Symbol(a, Decl(cyclicTypeInstantiation.ts, 9, 12))
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>T : Symbol(T, Decl(cyclicTypeInstantiation.ts, 8, 13))
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b: typeof x;
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>b : Symbol(b, Decl(cyclicTypeInstantiation.ts, 10, 13))
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>x : Symbol(x, Decl(cyclicTypeInstantiation.ts, 9, 7))
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};
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return x;
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>x : Symbol(x, Decl(cyclicTypeInstantiation.ts, 9, 7))
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}
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var a = foo<string>();
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>a : Symbol(a, Decl(cyclicTypeInstantiation.ts, 16, 3))
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>foo : Symbol(foo, Decl(cyclicTypeInstantiation.ts, 0, 0))
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var b = bar<string>();
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>b : Symbol(b, Decl(cyclicTypeInstantiation.ts, 17, 3))
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>bar : Symbol(bar, Decl(cyclicTypeInstantiation.ts, 6, 1))
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// Relating types of a and b produces instantiations of the cyclic anonymous types in foo and bar
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a = b;
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>a : Symbol(a, Decl(cyclicTypeInstantiation.ts, 16, 3))
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>b : Symbol(b, Decl(cyclicTypeInstantiation.ts, 17, 3))
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‎tests/baselines/reference/cyclicTypeInstantiation.types‎

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=== tests/cases/compiler/cyclicTypeInstantiation.ts ===
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function foo<T>() {
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>foo : <T>() => { a: T; b: any; }
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>T : T
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var x: {
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>x : { a: T; b: any; }
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a: T;
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>a : T
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>T : T
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b: typeof x;
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>b : { a: T; b: any; }
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>x : { a: T; b: any; }
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};
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return x;
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>x : { a: T; b: any; }
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}
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function bar<T>() {
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>bar : <T>() => { a: T; b: any; }
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>T : T
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var x: {
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>x : { a: T; b: any; }
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a: T;
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>a : T
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>T : T
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b: typeof x;
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>b : { a: T; b: any; }
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>x : { a: T; b: any; }
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};
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return x;
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>x : { a: T; b: any; }
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}
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var a = foo<string>();
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>a : { a: string; b: any; }
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>foo<string>() : { a: string; b: any; }
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>foo : <T>() => { a: T; b: any; }
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var b = bar<string>();
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>b : { a: string; b: any; }
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>bar<string>() : { a: string; b: any; }
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>bar : <T>() => { a: T; b: any; }
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// Relating types of a and b produces instantiations of the cyclic anonymous types in foo and bar
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a = b;
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>a = b : { a: string; b: any; }
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>a : { a: string; b: any; }
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>b : { a: string; b: any; }
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‎tests/cases/compiler/cyclicTypeInstantiation.ts‎

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function foo<T>() {
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var x: {
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a: T;
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b: typeof x;
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};
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return x;
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}
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function bar<T>() {
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var x: {
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a: T;
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b: typeof x;
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};
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return x;
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}
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var a = foo<string>();
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var b = bar<string>();
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// Relating types of a and b produces instantiations of the cyclic anonymous types in foo and bar
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a = b;

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