Suppress -Wunused-value within macros from system headers.

Along the way, move a helper function from SemaChecking.cpp to a more
accessible home in SourceManager.

llvm-svn: 147692

2 files changed, 33 insertions, 0 deletions

diff --git a/clang/test/Sema/Inputs/unused-expr-system-header.h b/clang/test/Sema/Inputs/unused-expr-system-header.h
new file mode 100644
index 00000000000..72b2d95de44
--- /dev/null
+++ b/clang/test/Sema/Inputs/unused-expr-system-header.h
@@ -0,0 +1,23 @@
+// "System header" for testing that -Wunused-value is properly suppressed in
+// certain cases.
+
+#define POSSIBLY_BAD_MACRO(x) \
+  { int i = x; \
+    i; }
+
+#define STATEMENT_EXPR_MACRO(x) \
+  (__extension__ \
+   ({int i = x; \
+     i;}))
+
+#define COMMA_MACRO_1(x, y) \
+  {x, y;}
+
+#define COMMA_MACRO_2(x, y) \
+  if (x) { 1 == 2, y; }
+
+#define COMMA_MACRO_3(x, y) \
+  (x, y)
+
+#define COMMA_MACRO_4(x, y) \
+  ( 1 == 2, y )
diff --git a/clang/test/Sema/unused-expr-system-header.c b/clang/test/Sema/unused-expr-system-header.c
new file mode 100644
index 00000000000..dcc8918970c
--- /dev/null
+++ b/clang/test/Sema/unused-expr-system-header.c
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -isystem %S/Inputs -fsyntax-only -verify %s
+#include <unused-expr-system-header.h>
+void f(int i1, int i2) {
+  POSSIBLY_BAD_MACRO(5);
+  STATEMENT_EXPR_MACRO(5);
+  COMMA_MACRO_1(i1 == i2, f(i1, i2)); // expected-warning {{expression result unused}}
+  COMMA_MACRO_2(i1 == i2, f(i1, i2));
+  COMMA_MACRO_3(i1 == i2, f(i1, i2)); // expected-warning {{expression result unused}}
+  COMMA_MACRO_4(i1 == i2, f(i1, i2));
+}