Add MA0201 for zero-valued enum flag checks#1163
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Add a new warning rule to detect constant enum flag checks when the checked flag value is 0, including ==, !=, is, is not, HasFlag, and HasFlags patterns. Also update MA0192 to skip zero-valued flags and refresh tests/documentation/config entries. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Resolve System.Enum.HasFlag during compilation start and report invocation diagnostics only for that method symbol. Custom extension methods such as HasFlags are no longer considered. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Resolve Enum.HasFlag with DocumentationCommentId directly in the CompilationStart callback and remove the extra lookup helper. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Move zero-valued enum flag diagnostics into the MA0192 analyzer class, remove the standalone MA0201 analyzer file, and keep both diagnostics in one analyzer class with dedicated tests and source documentation updates. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Consolidate zero-valued flag rule tests into UseHasFlagMethodAnalyzerTests and use explicit {|ruleid:code|} markers for expected diagnostics.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Drop MA0192_SeverityAndDefault and MA0201_SeverityAndDefault from UseHasFlagMethodAnalyzerTests per review feedback. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Updated [Meziantou.Analyzer](https://github.com/meziantou/Meziantou.Analyzer) from 3.0.85 to 3.0.89. <details> <summary>Release notes</summary> _Sourced from [Meziantou.Analyzer's releases](https://github.com/meziantou/Meziantou.Analyzer/releases)._ ## 3.0.89 NuGet package: <https://www.nuget.org/packages/Meziantou.Analyzer/3.0.89> ## What's Changed * Add opt-in MA0134 reporting for discarded awaitables by @meziantou in meziantou/Meziantou.Analyzer#1164 **Full Changelog**: meziantou/Meziantou.Analyzer@3.0.88...3.0.89 ## 3.0.88 NuGet package: <https://www.nuget.org/packages/Meziantou.Analyzer/3.0.88> ## What's Changed * Add MA0201 for zero-valued enum flag checks by @meziantou in meziantou/Meziantou.Analyzer#1163 **Full Changelog**: meziantou/Meziantou.Analyzer@3.0.87...3.0.88 ## 3.0.87 NuGet package: <https://www.nuget.org/packages/Meziantou.Analyzer/3.0.87> ## What's Changed * Fix MA0194 merge with existing and-patterns by @meziantou in meziantou/Meziantou.Analyzer#1162 **Full Changelog**: meziantou/Meziantou.Analyzer@3.0.86...3.0.87 ## 3.0.86 NuGet package: <https://www.nuget.org/packages/Meziantou.Analyzer/3.0.86> ## What's Changed * Improve MA0192 HasFlag detection for zero comparisons by @meziantou in meziantou/Meziantou.Analyzer#1161 **Full Changelog**: meziantou/Meziantou.Analyzer@3.0.85...3.0.86 Commits viewable in [compare view](meziantou/Meziantou.Analyzer@3.0.85...3.0.89). </details> [](https://docs.github.com/en/github/managing-security-vulnerabilities/about-dependabot-security-updates#about-compatibility-scores) Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting `@dependabot rebase`. [//]: # (dependabot-automerge-start) [//]: # (dependabot-automerge-end) --- <details> <summary>Dependabot commands and options</summary> <br /> You can trigger Dependabot actions by commenting on this PR: - `@dependabot rebase` will rebase this PR - `@dependabot recreate` will recreate this PR, overwriting any edits that have been made to it - `@dependabot show <dependency name> ignore conditions` will show all of the ignore conditions of the specified dependency - `@dependabot ignore this major version` will close this PR and stop Dependabot creating any more for this major version (unless you reopen the PR or upgrade to it yourself) - `@dependabot ignore this minor version` will close this PR and stop Dependabot creating any more for this minor version (unless you reopen the PR or upgrade to it yourself) - `@dependabot ignore this dependency` will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself) </details> Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
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Zero-valued enum members (
None = 0) make flag checks constant, but we did not have a dedicated rule to catch this. This adds a warning rule for these cases so users are alerted when the condition is always true or always false.What changed
MA0201(DoNotUseZeroValuedEnumFlagsInFlagChecks) as aUsagerule, warning severity, enabled by default.(value & flag) == ...(value & flag) != ...(value & flag) is ...(value & flag) is not ...value.HasFlag(...)when the checked flag value is zero.
System.Enum.HasFlagduring compilation start and reports diagnostics only for that exact method symbol. Custom extension methods are intentionally not analyzed.MA0192(UseHasFlagMethodAnalyzer) so it no longer reports zero-valued flag checks, avoiding conflicting guidance.MA0192interaction.docs/Rules/MA0201.mdRuleIdentifiers.editorconfigfilesREADME.mdanddocs/README.mdentries.