Fix MergeDeep in TypeScript 5.4
#806
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After the change in microsoft/TypeScript#56004 the `PickRestType` was causing some types to be considered theoretically infinite in their recursion. I can't wrap my mind around exactly why right now, but I can see how `PickRestType` on a crazy long tuple will cause a very deep recursion, so I decided to simply cap its recursion and return `unknown[]` if it goes past that point and that solved the errors. Side effects: - In practice: rarely any I believe - In theory: some merged types will regress to `unknown[]` in TypeScript versions older than 5.4 Considerations: Is the `DepthTracker extends Array<true> = []` + `PickRestTypeMaxDepth extends DepthTracker['length']` a good way to track depth? I know I have done a depth check previous times but can't remember what solution I picked then. Fixes #784
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Here's a canary run on this branch that shows that it fixes the problem: https://github.com/sindresorhus/type-fest/actions/runs/7697319193 |
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sorry not enough time to go further but #807 seems to fix the bug and improve performance |
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After the change in microsoft/TypeScript#56004 the
PickRestTypewas causing some types to be considered theoretically infinite in their recursion.I can't wrap my mind around exactly why right now, but I can see how
PickRestTypeon a crazy long tuple will cause a very deep recursion, so I decided to simply cap its recursion and returnunknown[]if it goes past that point and that solved the errors.Side effects:
unknown[]in TypeScript versions older than 5.4Considerations:
Is the
DepthTracker extends Array<true> = []+PickRestTypeMaxDepth extends DepthTracker['length']a good way to track depth? I know I have done a depth check previous times but can't remember what solution I picked then.Fixes #784