27 lines
879 B
Plaintext
27 lines
879 B
Plaintext
==== tests/cases/conformance/classes/members/inheritanceAndOverriding/derivedClassTransitivity.ts (1 errors) ====
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// subclassing is not transitive when you can remove required parameters and add optional parameters
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class C {
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foo(x: number) { }
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}
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class D extends C {
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foo() { } // ok to drop parameters
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}
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class E extends D {
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foo(x?: string) { } // ok to add optional parameters
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}
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var c: C;
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var d: D;
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var e: E;
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c = e;
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~
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!!! Type 'E' is not assignable to type 'C':
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!!! Types of property 'foo' are incompatible:
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!!! Type '(x?: string) => void' is not assignable to type '(x: number) => void':
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!!! Types of parameters 'x' and 'x' are incompatible:
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!!! Type 'string' is not assignable to type 'number'.
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var r = c.foo(1);
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var r2 = e.foo(''); |