Comments (11)
The actual behavior here matches the spec. It appears to be by design.
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Another interesting example where we don't error, but probably should:
var v: { [s: string]: string} = {
p: 3, // Expect an error here
q: null
}
This is a result of best common type losing information, and the nontransitivity of assignability.
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What's the action here? If we're aligned to spec, shouldn't this just be closed as by design?
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As I recall from discussion, the spec needs to be updated to align with the current behavior. Specifically, I think section 3.8.1 needs to not pull in call/construct/index signatures for the augmented types.
And it is a breaking change.
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I'm confused. You mention earlier that the "actual behavior here matches the spec. It appears to be by design." If so, is there a spec change?
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Yeah my previous comments were wrong because I misunderstood what was going on. Ignore those. It needs a spec change per my recent comment.
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Before we make this change, please confirm that the change does not impact real world code before we make the spec change.
from typescript.
Reopening this because the validation on real world code was not done yet.
from typescript.
Doesn't break any real world code we know of.
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Is this fixed, or by design?
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Fixed, in that it is a change from the old compiler. Spec has been updated to reflect behavior of the new compiler.
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Related Issues (20)
- Type guard fails to determine non null tuple property HOT 1
- Type discrimination bug with string literal tuple. HOT 4
- Native node TestContext.assert is not typed correctly HOT 4
- `"importHelpers": true` combined with `"module": "preserve"` results in undefined helper usage HOT 1
- Variance annotations in type aliases for interfaces do not affect assignability HOT 1
- Array.forEach args type error HOT 10
- `@deprecated` nested namespace handling is buggy HOT 2
- JSDoc @import statement for side effects HOT 5
- Alias import is moved incorrectly when moving code to another file
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- Find all references in TS is off by 1 line in this specific case HOT 4
- TS2454 Variable is used before being assigned with strictNullChecks when variable is clearly assigned but can be undefined
- Type PermissionName for Permission API doesn't contain microphone and camera devices HOT 2
- RangeError in Array destructuring assignment HOT 2
- Library method redefinition stopped working from 5.4 to 5.5 HOT 1
- Design Meeting Notes, 8/30/2024
- `this` becomes any inside function within object when using generic method types that `extends` + syntax highlighting breaks
- Inferred type incomplete, when inferring parameters type on surcharged constructors. HOT 11
- A mixin class must have a constructor with a single rest parameter of type any[] => this is wrong HOT 2
- Introduce "must-infer" generics to restrict user-specified type overrides HOT 5
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