40 lines
1.3 KiB
Plaintext
40 lines
1.3 KiB
Plaintext
==== tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithObjectTypeArgsAndConstraints3.ts (1 errors) ====
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// Generic call with constraints infering type parameter from object member properties
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class Base {
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x: string;
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}
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class Derived extends Base {
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y: string;
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}
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class Derived2 extends Base {
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z: string;
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}
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function f<T extends Base>(a: { x: T; y: T }) {
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var r: T;
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return r;
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}
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var r1 = f({ x: new Derived(), y: new Derived2() }); // ok, both extend Base
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function f2<T extends Base, U extends { x: T; y: T }>(a: U) {
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~~~~~~~~~~~~~~~~~~~~~~~~
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!!! Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
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var r: T;
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return r;
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}
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var r2 = f2({ x: new Derived(), y: new Derived2() }); // ok
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var r3 = f2({ x: new Derived(), y: new Derived2() }); // ok
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function f3<T extends Base>(y: (a: T) => T, x: T) {
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return y(null);
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}
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// all ok - T gets fixed too early, but then defaults to Base and everything works out
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var r4 = f3(x => x, new Base());
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var r5 = f3(x => x, new Derived());
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var r6 = f3(x => x, null);
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