Give better error messages when calling overloaded function with invalid types #672
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Also, if we can't give a specific message, we could print out the full signature of the target overloaded function as a note after the message. This would make it easier to see why the call is rejected by mypy. |
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I think just listing argument types and the overloads in a note may be enough. Also protocol notes already contain relevant code for nice compact formatting of overloads. |
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The implementation of protocol notes lives in |
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I'm working on it. |
Michael0x2a
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Resolves python#672 and supercedes python#5054. Currently, if a user calls an overloaded function and mypy is unable to find a match, mypy will display display a warning like 'No overload variant of "func" matches argument types" with no additional context. This pull request will list several matching variants in addition to that message. If possible, mypy will attempt to show only overloads that have a compatible number of arguments. The number of overloads shown is always capped at a maximum of 2. This pull request does *not* attempt to report a custom error when... 1. Union-math fails. Rationale: the pending PR will change how unions are handled dramatically enough to the point where any error handling here would be pointless. 2. Mypy is able to infer what signature the user most likely meant by looking at the erased types. Rationale: I attempted to implement this feature but was unable to make it consistently work without adding several ugly hacks around how mypy records errors so decided to defer implementing this feature.
Michael0x2a
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List possible overload variants when none match Resolves #672 and supersedes #5054. Currently, if a user calls an overloaded function and mypy is unable to find a match, mypy will display display a warning like 'No overload variant of "func" matches argument types" with no additional context. This pull request will list several matching variants in addition to that message. If possible, mypy will attempt to show only overloads that have a compatible number of arguments. The total number of extra lines of output printed is capped at 4 -- this means that the number of overloads shown is typically capped to a max of either 2 or 3. This pull request does *not* attempt to report a custom error when... 1. Union-math fails. Rationale: the pending PR will change how unions are handled dramatically enough to the point where any error handling here would be pointless. 2. Mypy is able to infer what signature the user most likely meant by looking at the erased types. Rationale: I attempted to implement this feature but was unable to make it consistently work without adding several ugly hacks around how mypy records errors so decided to defer implementing this feature.
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Currently when calling an overloaded function, the error message is something like
No overload variant of "foo" matches argument types. Instead, we should try to give a message likeArgument 1 to "foo" has incompatible type "int"; expected "str" or "bytes", which is more informative. This may not be always possible, but we should be able to do it at least most of the time.The text was updated successfully, but these errors were encountered: