Introduce __has_feature(attribute_unused_on_fields) to determine whether

the current version of clang understands __attribute__((unused)) on
fields.

llvm-svn: 159252

2 files changed, 8 insertions, 0 deletions

diff --git a/clang/lib/Lex/PPMacroExpansion.cpp b/clang/lib/Lex/PPMacroExpansion.cpp
index c6aabde03e0..a46e31af446 100644
--- a/clang/lib/Lex/PPMacroExpansion.cpp
+++ b/clang/lib/Lex/PPMacroExpansion.cpp
@@ -632,6 +632,7 @@ static bool HasFeature(const Preprocessor &PP, const IdentifierInfo *II) {
            .Case("attribute_objc_method_family", true)
            .Case("attribute_overloadable", true)
            .Case("attribute_unavailable_with_message", true)
+           .Case("attribute_unused_on_fields", true)
            .Case("blocks", LangOpts.Blocks)
            .Case("cxx_exceptions", LangOpts.Exceptions)
            .Case("cxx_rtti", LangOpts.RTTI)
diff --git a/clang/test/SemaCXX/warn-unused-member.cpp b/clang/test/SemaCXX/warn-unused-member.cpp
index cabc9b6cd6a..6a7922e8e55 100644
--- a/clang/test/SemaCXX/warn-unused-member.cpp
+++ b/clang/test/SemaCXX/warn-unused-member.cpp
@@ -144,6 +144,13 @@ class EverythingUsed {
   int by_initializer_;
 };
 
+class HasFeatureTest {
+#if __has_feature(attribute_unused_on_fields)
+  int unused_; // expected-warning{{private field 'unused_' is not used}}
+  int unused2_ __attribute__((unused)); // no-warning
+#endif
+};
+
 namespace templates {
 class B {
   template <typename T> void f(T t);