diff options
author | Richard Trieu <rtrieu@google.com> | 2019-10-19 00:57:23 +0000 |
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committer | Richard Trieu <rtrieu@google.com> | 2019-10-19 00:57:23 +0000 |
commit | a27ae544f30bfd7dc765b8a6080190d39d893b99 (patch) | |
tree | 20f6b66320ee0e421f33e6e54eab73db57932762 /lib/Sema/AnalysisBasedWarnings.cpp | |
parent | 7decfe83555385bebac2e4bed35035f3b0f4d666 (diff) | |
download | clang-a27ae544f30bfd7dc765b8a6080190d39d893b99.tar.gz |
New tautological warning for bitwise-or with non-zero constant always true.
Taking a value and the bitwise-or it with a non-zero constant will always
result in a non-zero value. In a boolean context, this is always true.
if (x | 0x4) {} // always true, intended '&'
This patch creates a new warning group -Wtautological-bitwise-compare for this
warning. It also moves in the existing tautological bitwise comparisons into
this group. A few other changes were needed to the CFGBuilder so that all bool
contexts would be checked. The warnings in -Wtautological-bitwise-compare will
be off by default due to using the CFG.
Fixes: https://bugs.llvm.org/show_bug.cgi?id=42666
Differential Revision: https://reviews.llvm.org/D66046
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@375318 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Sema/AnalysisBasedWarnings.cpp')
-rw-r--r-- | lib/Sema/AnalysisBasedWarnings.cpp | 24 |
1 files changed, 18 insertions, 6 deletions
diff --git a/lib/Sema/AnalysisBasedWarnings.cpp b/lib/Sema/AnalysisBasedWarnings.cpp index 01648fea8d..2c70c0599e 100644 --- a/lib/Sema/AnalysisBasedWarnings.cpp +++ b/lib/Sema/AnalysisBasedWarnings.cpp @@ -159,6 +159,20 @@ public: S.Diag(B->getExprLoc(), diag::warn_comparison_bitwise_always) << DiagRange << isAlwaysTrue; } + + void compareBitwiseOr(const BinaryOperator *B) override { + if (HasMacroID(B)) + return; + + SourceRange DiagRange = B->getSourceRange(); + S.Diag(B->getExprLoc(), diag::warn_comparison_bitwise_or) << DiagRange; + } + + static bool hasActiveDiagnostics(DiagnosticsEngine &Diags, + SourceLocation Loc) { + return !Diags.isIgnored(diag::warn_tautological_overlap_comparison, Loc) || + !Diags.isIgnored(diag::warn_comparison_bitwise_or, Loc); + } }; } // anonymous namespace @@ -2070,10 +2084,9 @@ AnalysisBasedWarnings::IssueWarnings(sema::AnalysisBasedWarnings::Policy P, .setAlwaysAdd(Stmt::AttributedStmtClass); } - // Install the logical handler for -Wtautological-overlap-compare + // Install the logical handler. llvm::Optional<LogicalErrorHandler> LEH; - if (!Diags.isIgnored(diag::warn_tautological_overlap_comparison, - D->getBeginLoc())) { + if (LogicalErrorHandler::hasActiveDiagnostics(Diags, D->getBeginLoc())) { LEH.emplace(S); AC.getCFGBuildOptions().Observer = &*LEH; } @@ -2222,9 +2235,8 @@ AnalysisBasedWarnings::IssueWarnings(sema::AnalysisBasedWarnings::Policy P, checkThrowInNonThrowingFunc(S, FD, AC); // If none of the previous checks caused a CFG build, trigger one here - // for -Wtautological-overlap-compare - if (!Diags.isIgnored(diag::warn_tautological_overlap_comparison, - D->getBeginLoc())) { + // for the logical error handler. + if (LogicalErrorHandler::hasActiveDiagnostics(Diags, D->getBeginLoc())) { AC.getCFG(); } |