Don't emit -Wunused-value warnings from macro expansions.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@166522 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 11 insertions, 0 deletions

diff --git a/lib/AST/Expr.cpp b/lib/AST/Expr.cpp
index 3c8cbb56a0..68bce4b6f6 100644
--- a/lib/AST/Expr.cpp
+++ b/lib/AST/Expr.cpp
@@ -2026,6 +2026,10 @@ bool Expr::isUnusedResultAWarning(const Expr *&WarnE, SourceLocation &Loc,
   }
   case CXXFunctionalCastExprClass:
   case CStyleCastExprClass: {
+    // Ignore casts within macro expansions.
+    if (getExprLoc().isMacroID())
+      return false;
+
     // Ignore an explicit cast to void unless the operand is a non-trivial
     // volatile lvalue.
     const CastExpr *CE = cast<CastExpr>(this);
diff --git a/test/Sema/unused-expr.c b/test/Sema/unused-expr.c
index 056d09a871..6677e48300 100644
--- a/test/Sema/unused-expr.c
+++ b/test/Sema/unused-expr.c
@@ -122,3 +122,10 @@ void f(int i, ...) {
 
 // PR8371
 int fn5() __attribute__ ((__const));
+
+// OpenSSL has some macros like this.
+#define M(a, b) (long)foo((a), (b))
+void t11(int i, int j) {
+  M(i, j);  // no warning
+}
+#undef M