Add MA0194 to merge repeated is-pattern checks#1107
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Introduce MA0194 with analyzer and fixer to merge repeated is-pattern checks on the same expression into combined patterns where valid. Add focused tests and regenerate rule documentation and generated rule tables/configuration. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Set MA0194 to be enabled by default at suggestion severity and add a rule metadata test. Regenerate documentation and default editorconfig outputs to reflect the new default. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
This was referenced Apr 29, 2026
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This was referenced May 1, 2026
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Why
Pattern checks like
value is A || value is Bare harder to read and maintain than a single combined pattern. This change adds a dedicated rule to encourage the more idiomatic C# pattern-combinator form when both checks target the same value.What changed
MA0194(MergeIsPatternChecks) inRuleIdentifiers.MergeIsPatternChecksAnalyzerto detect mergeable logical chains ofischecks on the same expression.MergeIsPatternChecksFixerto rewrite mergeable chains into combinedor/and/notpatterns while preserving precedence.MergeIsPatternChecksAnalyzerTestscovering:||merges&&merges includingnotdocs/Rules/MA0194.mdand regenerated generated documentation/config files (README.md,docs/README.md, and pack editorconfig files).Notes for reviewers
&&chains of only positive constant patterns (for examplevalue is A && value is B), the rule still reports, but the code fix intentionally does not merge that specific case because the directandrewrite is rejected by the compiler (CS8518).