Attempt a couple type error improvements#5837
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This tweaks to type checking aspects to attempt to get nicer errors. 1. Remove the `InMatch` scope from the _checking_ path. This causes the error extractor that reports incoherent branch types from triggering, so that you don't get the error when _annotating_ the match with a different type. This is similar to how if statements are set up, which didn't seem subject to the same problem. 2. Add an `InActionRestriction` scope to the checker and use it around subtyping checks against `Unit` in blocks. This allows us to match the extra scope information and report a customized error. This allows circumventing another situation where the block failure would be reported as a "branches have different types" error when it happened inside a match, even though that makes no sense.
aryairani
approved these changes
Aug 14, 2025
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Oh gosh. Github's auto-merge doesn't wait for CI. What a useless feature. |
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Author
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So, wait, are there still CI failures from this? |
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@dolio Yes; looks like probably a merge issue with trunk and the transcript. |
aryairani
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Aug 14, 2025
Missing transcript update from #5837
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There's some way to tweak those settings; it works great in |
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This tweaks to type checking aspects to attempt to get nicer errors.
Remove the
InMatchscope from the checking path. This causes the error extractor that reports incoherent branch types from triggering, so that you don't get the error when annotating the match with a different type. This is similar to how if statements are set up, which didn't seem subject to the same problem.Add an
InActionRestrictionscope to the checker and use it around subtyping checks againstUnitin blocks. This allows us to match the extra scope information and report a customized error.This allows circumventing another situation where the block failure would be reported as a "branches have different types" error when it happened inside a match, even though that makes no sense.
Fixes #5283 and #5217