feat: Feature a "type annotations needed" diagnostic#22144
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ChayimFriedman2 merged 1 commit intorust-lang:masterfrom Apr 24, 2026
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feat: Feature a "type annotations needed" diagnostic#22144ChayimFriedman2 merged 1 commit intorust-lang:masterfrom
ChayimFriedman2 merged 1 commit intorust-lang:masterfrom
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There are two kinds of this diagnostic: 1 Some constructs, like calling or indexing, require the type to be known *immediately*. 2. Otherwise, if we cannot resolve the variable at the end of inference, it's an error. This PR implements only the first kind, which is also simpler to implement. We just need to push an error in `structurally_resolve_type()` (as opposed to `try_structurally_resolve_type()` that never errors) if the type cannot be resolved, and of course also make sure we only call this function where rustc does. The second case needs to track the origin of infer vars, and it's for another time.
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This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed. Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers. |
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There are two kinds of this diagnostic:
1 Some constructs, like calling or indexing, require the type to be known immediately.
2. Otherwise, if we cannot resolve the variable at the end of inference, it's an error.
This PR implements only the first kind, which is also simpler to implement. We just need to push an error in
structurally_resolve_type()(as opposed totry_structurally_resolve_type()that never errors) if the type cannot be resolved, and of course also make sure we only call this function where rustc does.The second case needs to track the origin of infer vars, and it's for another time.
Blocked on #22141.