diff options
| -rw-r--r-- | lib/Sema/SemaStmt.cpp | 7 | ||||
| -rw-r--r-- | test/Frontend/macros.c | 8 |
2 files changed, 15 insertions, 0 deletions
diff --git a/lib/Sema/SemaStmt.cpp b/lib/Sema/SemaStmt.cpp index c885d484e7..76410e20ac 100644 --- a/lib/Sema/SemaStmt.cpp +++ b/lib/Sema/SemaStmt.cpp @@ -160,6 +160,13 @@ void Sema::DiagnoseUnusedExprResult(const Stmt *S) { !E->isUnusedResultAWarning(WarnExpr, Loc, R1, R2, Context)) return; + // If this is a GNU statement expression expanded from a macro, it is probably + // unused because it is a function-like macro that can be used as either an + // expression or statement. Don't warn, because it is almost certainly a + // false positive. + if (isa<StmtExpr>(E) && Loc.isMacroID()) + return; + // Okay, we have an unused result. Depending on what the base expression is, // we might want to make a more specific diagnostic. Check for one of these // cases now. diff --git a/test/Frontend/macros.c b/test/Frontend/macros.c index 317079709c..828c762840 100644 --- a/test/Frontend/macros.c +++ b/test/Frontend/macros.c @@ -2,3 +2,11 @@ int a[(B A) == 1 ? 1 : -1]; + +// PR13747 - Don't warn about unused results with statement exprs in macros. +void stuff(int,int,int); +#define memset(x,y,z) ({ stuff(x,y,z); x; }) + +void foo(int a, int b, int c) { + memset(a,b,c); // No warning! +} |