diff options
| -rw-r--r-- | lib/Sema/SemaExpr.cpp | 15 | ||||
| -rw-r--r-- | test/Sema/self-comparison.c | 10 |
2 files changed, 12 insertions, 13 deletions
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp index b907675b96..57b4232294 100644 --- a/lib/Sema/SemaExpr.cpp +++ b/lib/Sema/SemaExpr.cpp @@ -5319,17 +5319,18 @@ QualType Sema::CheckCompareOperands(Expr *&lex, Expr *&rex, SourceLocation Loc, // For non-floating point types, check for self-comparisons of the form // x == x, x != x, x < x, etc. These always evaluate to a constant, and // often indicate logic errors in the program. - // NOTE: Don't warn about comparisons of enum constants. These can arise - // from macro expansions, and are usually quite deliberate. Also don't - // warn about comparisons which are only self comparisons within - // a template specialization. The warnings should catch obvious cases in - // the definition of the template anyways. + // + // NOTE: Don't warn about comparison expressions resulting from macro + // expansion. Also don't warn about comparisons which are only self + // comparisons within a template specialization. The warnings should catch + // obvious cases in the definition of the template anyways. The idea is to + // warn when the typed comparison operator will always evaluate to the same + // result. Expr *LHSStripped = lex->IgnoreParens(); Expr *RHSStripped = rex->IgnoreParens(); if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LHSStripped)) { if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RHSStripped)) { - if (DRL->getDecl() == DRR->getDecl() && - !isa<EnumConstantDecl>(DRL->getDecl()) && + if (DRL->getDecl() == DRR->getDecl() && !Loc.isMacroID() && !IsWithinTemplateSpecialization(DRL->getDecl())) { DiagRuntimeBehavior(Loc, PDiag(diag::warn_comparison_always) << 0 // self- diff --git a/test/Sema/self-comparison.c b/test/Sema/self-comparison.c index 27d1eb3d40..c5c0611e7c 100644 --- a/test/Sema/self-comparison.c +++ b/test/Sema/self-comparison.c @@ -34,12 +34,10 @@ int bar2(float x) { return x != x; // no-warning } -// Motivated by <rdar://problem/6703892>, self-comparisons of enum constants -// should not be warned about. These can be expanded from macros, and thus -// are usually deliberate. -int compare_enum() { - enum { A }; - return A == A; // no-warning +#define IS_THE_ANSWER(x) (x == 42) + +int macro_comparison() { + return IS_THE_ANSWER(42); } // Don't complain in unevaluated contexts. |