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Fix inference for generic-typed constructor parameter when no explicit constructor is present (#47750)
* assume signature is from constructor if declaration is undefined * add tests and baselines
1 parent 67172e4 commit 1e60c87

5 files changed

+277
-2
lines changed

‎src/compiler/checker.ts

Lines changed: 5 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -13077,8 +13077,11 @@ namespace ts {
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// object type literal or interface (using the new keyword). Each way of declaring a constructor
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// will result in a different declaration kind.
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if (!signature.isolatedSignatureType) {
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const kind = signature.declaration ? signature.declaration.kind : SyntaxKind.Unknown;
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const isConstructor = kind === SyntaxKind.Constructor || kind === SyntaxKind.ConstructSignature || kind === SyntaxKind.ConstructorType;
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const kind = signature.declaration?.kind;
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// If declaration is undefined, it is likely to be the signature of the default constructor.
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const isConstructor = kind === undefined || kind === SyntaxKind.Constructor || kind === SyntaxKind.ConstructSignature || kind === SyntaxKind.ConstructorType;
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const type = createObjectType(ObjectFlags.Anonymous);
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type.members = emptySymbols;
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type.properties = emptyArray;

‎tests/baselines/reference/inferringReturnTypeFromConstructSignatureGeneric.js

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//// [inferringReturnTypeFromConstructSignatureGeneric.ts]
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class GenericObject<T extends {} = {}> {
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give(value: T) {
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return value;
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}
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}
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class GenericNumber<T extends number> {
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give(value: T) {
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return value;
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}
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}
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class GenericNumberOrString<T extends number | string> {
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give(value: T) {
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return value;
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}
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}
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function g<T>(type: new () => T): T {
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return new type();
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}
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const g1 = g(GenericObject);
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g1.give({});
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const g2 = g(GenericNumber);
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g2.give(1);
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const g3 = g(GenericNumberOrString);
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g3.give(1);
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g3.give('1');
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//// [inferringReturnTypeFromConstructSignatureGeneric.js]
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var GenericObject = /** @class */ (function () {
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function GenericObject() {
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}
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GenericObject.prototype.give = function (value) {
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return value;
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};
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return GenericObject;
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}());
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var GenericNumber = /** @class */ (function () {
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function GenericNumber() {
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}
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GenericNumber.prototype.give = function (value) {
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return value;
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};
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return GenericNumber;
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}());
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var GenericNumberOrString = /** @class */ (function () {
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function GenericNumberOrString() {
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}
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GenericNumberOrString.prototype.give = function (value) {
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return value;
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};
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return GenericNumberOrString;
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}());
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function g(type) {
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return new type();
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}
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var g1 = g(GenericObject);
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g1.give({});
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var g2 = g(GenericNumber);
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g2.give(1);
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var g3 = g(GenericNumberOrString);
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g3.give(1);
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g3.give('1');

‎tests/baselines/reference/inferringReturnTypeFromConstructSignatureGeneric.symbols

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=== tests/cases/compiler/inferringReturnTypeFromConstructSignatureGeneric.ts ===
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class GenericObject<T extends {} = {}> {
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>GenericObject : Symbol(GenericObject, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 0, 0))
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>T : Symbol(T, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 0, 20))
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give(value: T) {
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>give : Symbol(GenericObject.give, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 0, 40))
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>value : Symbol(value, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 1, 7))
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>T : Symbol(T, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 0, 20))
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return value;
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>value : Symbol(value, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 1, 7))
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}
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}
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class GenericNumber<T extends number> {
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>GenericNumber : Symbol(GenericNumber, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 4, 1))
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>T : Symbol(T, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 5, 20))
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give(value: T) {
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>give : Symbol(GenericNumber.give, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 5, 39))
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>value : Symbol(value, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 6, 7))
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>T : Symbol(T, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 5, 20))
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return value;
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>value : Symbol(value, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 6, 7))
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}
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}
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class GenericNumberOrString<T extends number | string> {
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>GenericNumberOrString : Symbol(GenericNumberOrString, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 9, 1))
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>T : Symbol(T, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 10, 28))
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give(value: T) {
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>give : Symbol(GenericNumberOrString.give, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 10, 56))
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>value : Symbol(value, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 11, 7))
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>T : Symbol(T, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 10, 28))
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return value;
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>value : Symbol(value, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 11, 7))
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}
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}
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function g<T>(type: new () => T): T {
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>g : Symbol(g, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 14, 1))
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>T : Symbol(T, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 16, 11))
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>type : Symbol(type, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 16, 14))
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>T : Symbol(T, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 16, 11))
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>T : Symbol(T, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 16, 11))
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return new type();
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>type : Symbol(type, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 16, 14))
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}
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const g1 = g(GenericObject);
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>g1 : Symbol(g1, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 20, 5))
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>g : Symbol(g, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 14, 1))
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>GenericObject : Symbol(GenericObject, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 0, 0))
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g1.give({});
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>g1.give : Symbol(GenericObject.give, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 0, 40))
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>g1 : Symbol(g1, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 20, 5))
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>give : Symbol(GenericObject.give, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 0, 40))
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const g2 = g(GenericNumber);
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>g2 : Symbol(g2, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 23, 5))
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>g : Symbol(g, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 14, 1))
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>GenericNumber : Symbol(GenericNumber, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 4, 1))
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g2.give(1);
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>g2.give : Symbol(GenericNumber.give, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 5, 39))
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>g2 : Symbol(g2, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 23, 5))
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>give : Symbol(GenericNumber.give, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 5, 39))
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const g3 = g(GenericNumberOrString);
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>g3 : Symbol(g3, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 26, 5))
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>g : Symbol(g, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 14, 1))
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>GenericNumberOrString : Symbol(GenericNumberOrString, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 9, 1))
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g3.give(1);
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>g3.give : Symbol(GenericNumberOrString.give, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 10, 56))
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>g3 : Symbol(g3, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 26, 5))
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>give : Symbol(GenericNumberOrString.give, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 10, 56))
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g3.give('1');
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>g3.give : Symbol(GenericNumberOrString.give, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 10, 56))
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>g3 : Symbol(g3, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 26, 5))
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>give : Symbol(GenericNumberOrString.give, Decl(inferringReturnTypeFromConstructSignatureGeneric.ts, 10, 56))
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‎tests/baselines/reference/inferringReturnTypeFromConstructSignatureGeneric.types

Lines changed: 90 additions & 0 deletions
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@@ -0,0 +1,90 @@
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=== tests/cases/compiler/inferringReturnTypeFromConstructSignatureGeneric.ts ===
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class GenericObject<T extends {} = {}> {
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>GenericObject : GenericObject<T>
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give(value: T) {
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>give : (value: T) => T
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>value : T
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return value;
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>value : T
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}
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}
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class GenericNumber<T extends number> {
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>GenericNumber : GenericNumber<T>
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give(value: T) {
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>give : (value: T) => T
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>value : T
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return value;
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>value : T
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}
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}
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class GenericNumberOrString<T extends number | string> {
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>GenericNumberOrString : GenericNumberOrString<T>
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give(value: T) {
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>give : (value: T) => T
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>value : T
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return value;
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>value : T
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}
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}
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function g<T>(type: new () => T): T {
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>g : <T>(type: new () => T) => T
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>type : new () => T
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return new type();
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>new type() : T
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>type : new () => T
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}
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const g1 = g(GenericObject);
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>g1 : GenericObject<{}>
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>g(GenericObject) : GenericObject<{}>
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>g : <T>(type: new () => T) => T
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>GenericObject : typeof GenericObject
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g1.give({});
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>g1.give({}) : {}
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>g1.give : (value: {}) => {}
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>g1 : GenericObject<{}>
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>give : (value: {}) => {}
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>{} : {}
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const g2 = g(GenericNumber);
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>g2 : GenericNumber<number>
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>g(GenericNumber) : GenericNumber<number>
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>g : <T>(type: new () => T) => T
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>GenericNumber : typeof GenericNumber
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g2.give(1);
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>g2.give(1) : number
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>g2.give : (value: number) => number
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>g2 : GenericNumber<number>
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>give : (value: number) => number
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>1 : 1
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const g3 = g(GenericNumberOrString);
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>g3 : GenericNumberOrString<string | number>
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>g(GenericNumberOrString) : GenericNumberOrString<string | number>
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>g : <T>(type: new () => T) => T
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>GenericNumberOrString : typeof GenericNumberOrString
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g3.give(1);
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>g3.give(1) : string | number
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>g3.give : (value: string | number) => string | number
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>g3 : GenericNumberOrString<string | number>
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>give : (value: string | number) => string | number
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>1 : 1
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g3.give('1');
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>g3.give('1') : string | number
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>g3.give : (value: string | number) => string | number
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>g3 : GenericNumberOrString<string | number>
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>give : (value: string | number) => string | number
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>'1' : "1"
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‎tests/cases/compiler/inferringReturnTypeFromConstructSignatureGeneric.ts

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class GenericObject<T extends {} = {}> {
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give(value: T) {
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return value;
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}
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}
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class GenericNumber<T extends number> {
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give(value: T) {
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return value;
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}
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}
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class GenericNumberOrString<T extends number | string> {
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give(value: T) {
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return value;
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}
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}
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function g<T>(type: new () => T): T {
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return new type();
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}
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const g1 = g(GenericObject);
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g1.give({});
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const g2 = g(GenericNumber);
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g2.give(1);
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const g3 = g(GenericNumberOrString);
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g3.give(1);
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g3.give('1');

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