7c89e389d0
Support HIR wf checking for function signatures During function type-checking, we normalize any associated types in the function signature (argument types + return type), and then create WF obligations for each of the normalized types. The HIR wf code does not currently support this case, so any errors that we get have imprecise spans. This commit extends `ObligationCauseCode::WellFormed` to support recording a function parameter, allowing us to get the corresponding HIR type if an error occurs. Function typechecking is modified to pass this information during signature normalization and WF checking. The resulting code is fairly verbose, due to the fact that we can no longer normalize the entire signature with a single function call. As part of the refactoring, we now perform HIR-based WF checking for several other 'typed items' (statics, consts, and inherent impls). As a result, WF and projection errors in a function signature now have a precise span, which points directly at the responsible type. If a function signature is constructed via a macro, this will allow the error message to point at the code 'most responsible' for the error (e.g. a user-supplied macro argument). |
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| Cargo.toml | ||
| README.md | ||
For high-level intro to how type checking works in rustc, see the type checking chapter of the rustc dev guide.