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Stack overflow error when using inline mapped tuplesΒ #53458
Description
Bug Report
π Search Terms
Maximum call stack size exceeded
getMappedType
π Version & Regression Information
- This is a crash
- This changed between versions 4.6.4 and 4.7.4
β― Playground Link
Playground link with relevant code
π» Code
class Foo<Elements extends readonly unknown[]> {
public readonly elements: { [P in keyof Elements]: { bar: Elements[P]; } };
public constructor(...elements: { [P in keyof Elements]: { bar: Elements[P] } }) {
this.elements = elements;
}
public add(): Foo<[...Elements, 'abc']> {
return new Foo<[...Elements, 'abc']>(...this.elements, { bar: 'abc' });
}
}π Actual behavior
The compiler crashes with a stack overflow error
π Expected behavior
Compilation should succeed with no errors. Extracting the inline mapped type to its own type definition achieves this, but the two are logically identical so the stack overflow is unexpected.
Activity
fatcerberus commentedon Mar 23, 2023
You maniac! You blew it up! Damn you!
π
RyanCavanaugh commentedon Mar 23, 2023
Strong contender for the "crash which was oldest at the point it was first found" award of 2023.
Let me know if you're actually blocked by this (sounds like no?) and if so I'll assign it out instead of backlog.
danny-may commentedon Mar 23, 2023
Not blocked by this, giving a name to the mapped type seems to fix this for whatever reason and to be honest ends up being more readable than having it inline. I just noticed this while doing some quick prototyping and was very confused as to why vscode stopped giving me errors all of a sudden.
Andarist commentedon Mar 23, 2023
A more detailed call stack for those who might be interested where this happens :P
danny-may commentedon Mar 23, 2023
Damn, I did some more playing and it looks like this has only been an issue since 4.7.4. Looks like changing versions in the playground doesnt cause errors to appear immediately. There goes my award π’
fatcerberus commentedon Mar 23, 2023
Normally that takes effect immediately, but since this is actually crashing the compiler, it might be taking longer to recover from or something.