3 files changed, 12 insertions, 3 deletions
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index eece90b42a6..cd6f6894d90 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -682,6 +682,8 @@ def warn_redeclaration_without_attribute_prev_attribute_ignored : Warning<
 def warn_attribute_ignored : Warning<"%0 attribute ignored">;
 def warn_attribute_precede_definition : Warning<
   "attribute declaration must precede definition">;
+def warn_attribute_void_function : Warning<
+  "attribute %0 cannot be applied to functions without return value">;
 def warn_attribute_weak_on_field : Warning<
   "__weak attribute cannot be specified on a field declaration">;
 def warn_attribute_weak_on_local : Warning<
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 718db0437f4..e95f479bd8e 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -730,13 +730,18 @@ static void HandleWarnUnusedResult(Decl *D, const AttributeList &Attr, Sema &S)
     return;
   }
 
-  // TODO: could also be applied to methods?
   if (!isFunctionOrMethod(D)) {
     S.Diag(Attr.getLoc(), diag::warn_attribute_wrong_decl_type)
       << Attr.getName() << 0 /*function*/;
     return;
   }
 
+  if (getFunctionType(D)->getResultType()->isVoidType()) {
+    S.Diag(Attr.getLoc(), diag::warn_attribute_void_function)
+      << Attr.getName();
+    return;
+  }
+
   D->addAttr(::new (S.Context) WarnUnusedResultAttr());
 }
 
diff --git a/clang/test/Sema/unused-expr.c b/clang/test/Sema/unused-expr.c
index 284818dc581..30f6aee26b4 100644
--- a/clang/test/Sema/unused-expr.c
+++ b/clang/test/Sema/unused-expr.c
@@ -87,17 +87,19 @@ int fn3() __attribute__ ((const));
 int t6() {
   if (fn1() < 0 || fn2(2,1) < 0 || fn3(2) < 0)  // no warnings
     return -1;
-  
+
   fn1();  // expected-warning {{ignoring return value of function declared with warn_unused_result attribute}}
   fn2(92, 21);  // expected-warning {{ignoring return value of function declared with pure attribute}}
   fn3(42);  // expected-warning {{ignoring return value of function declared with const attribute}}
   return 0;
 }
 
-int t7 __attribute__ ((warn_unused_result)); // expected-warning {{warning: 'warn_unused_result' attribute only applies to function types}}
+int t7 __attribute__ ((warn_unused_result)); // expected-warning {{'warn_unused_result' attribute only applies to function types}}
 
 // PR4010
 int (*fn4)(void) __attribute__ ((warn_unused_result));
 void t8() {
   fn4(); // expected-warning {{ignoring return value of function declared with warn_unused_result attribute}}
 }
+
+void t9() __attribute__((warn_unused_result)); // expected-warning {{attribute 'warn_unused_result' cannot be applied to functions without return value}}