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Readonly vs. litteral type breaking change? #12148
Description
TypeScript Version: 2.1.1
Code
class A {
readonly n = 0;
constructor() {
this.n = 1; // Type '1' is not assignable to type '0'
}
}
class B {
constructor(readonly n = 0) {}
}
class C extends B {
constructor() {
super(1); // Argument of type '1' is not assignable to parameter of type '0 | undefined'.
}
}Expected behavior:
Is this behavior expected (breaking change vs 2.0.8)?
To me this should be valid, particularly the 2nd case.
Actual behavior:
Errors displayed in comments.
Activity
falsandtru commentedon Nov 10, 2016
#11409
mhegazy commentedon Nov 14, 2016
All parameter initializes should be widened to their base (e.g. class
B), property initializes (e.g. classA) are intentional breaking change.sandersn commentedon Nov 16, 2016
Fix is up at #12312