Add analyzer for identical conditional compilation branches#1169
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Add MA0202 to detect identical code across #if/#elif/#else branches in the same conditional compilation block, with tests and generated documentation/configuration updates. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
This was referenced May 23, 2026
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Why
Conditional compilation blocks can easily accumulate duplicated branches (for example
#ifand#elifwith the same body), which adds noise and can hide unnecessary conditions. This change adds an explicit analyzer rule to surface those duplicates.What changed
MA0202and a new analyzer:ConditionalCompilationBranchesAreIdenticalAnalyzer.#if ... #endifdirective groups and compares branch bodies (#if,#elif,#else) using token-based signatures so trivia differences (whitespace/comments) do not prevent detection.#ifvs#elifduplicates#ifvs#elseduplicatesdocs/Rules/MA0202.md) and regenerated rule listings/editorconfig outputs.Validation
dotnet builddotnet test --filter "FullyQualifiedName~ConditionalCompilationBranchesAreIdenticalAnalyzerTests"dotnet test /p:RoslynVersion=roslyn4.2 --filter "FullyQualifiedName~ConditionalCompilationBranchesAreIdenticalAnalyzerTests"dotnet test /p:RoslynVersion=roslyn4.14 --filter "FullyQualifiedName~ConditionalCompilationBranchesAreIdenticalAnalyzerTests"