Add unreachable-match-patterns message and new checker.
#10424
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Codecov ReportAll modified and coverable lines are covered by tests β
Additional details and impacted files@@ Coverage Diff @@
## main #10424 +/- ##
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Coverage 95.86% 95.87%
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Files 175 177 +2
Lines 19074 19153 +79
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+ Hits 18286 18363 +77
- Misses 788 790 +2
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``unreachable-match-patterns``. This will emit an error message when a name capture pattern is used in a match statement which would make the remaining patterns unreachable. This code is a SyntaxError at runtime. Closes pylint-dev#7128
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remaining-patterns-unreachable checker.unreachable-match-patterns message and new checker.
| and case.pattern.pattern is None | ||
| and isinstance(case.pattern.name, nodes.AssignName) | ||
| and idx < len(node.cases) - 1 | ||
| and self._py310_plus |
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Why check the version? Shouldn't this always be checked if we find these patterns?
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Why check the version?
My mistake. We shouldn't check it. I must have been thinking that this line would prevent an error from occurring if Pylint was run in an environment using Python 3.9 or lower since the match statement (and the ast.Match node) is only available in Python 3.10 and higher.
The solution would be to remove this line and wait until Python 3.9 is end of life before considering a merge?
| Match Statements checker Messages | ||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
| :unreachable-match-patterns (E5000): *The name capture `case %s` makes the remaining patterns unreachable. Use a dotted name(for example an enum) to fix this* | ||
| Emitted when a name capture pattern in a match statement is used and there |
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| Emitted when a name capture pattern in a match statement is used and there | |
| Emitted when a name capture pattern is used in a match statement and there |
| msgs = { | ||
| "E5000": ( | ||
| "The name capture `case %s` makes the remaining patterns unreachable. " | ||
| "Use a dotted name(for example an enum) to fix this", |
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| "Use a dotted name(for example an enum) to fix this", | |
| "Use a dotted name (for example an enum) to fix this.", |
| case red: # [unreachable-match-patterns] | ||
| print("I see red!") | ||
| case green: # [unreachable-match-patterns] | ||
| print("Grass is green") | ||
| case blue: | ||
| print("I'm feeling the blues :(") |
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I'm a little torn, but I guess I would expect to see this message on the second and third cases, not the first and second, since it's the second and third that are unreachable. We don't know if the fix is to alter the name capture or to remove the extra cases.
Type of Changes
Description
This will emit an error message when a name capture pattern is used in a match statement which would make the remaining patterns unreachable. This code is a SyntaxError at runtime.
Closes #7128