Fix false positive in -Wunused-variable when a ctor call make involve cleanups.

llvm-svn: 166625

clang/lib/Sema/SemaDecl.cpp

@@ -1286,6 +1286,8 @@ static bool ShouldDiagnoseUnusedDecl(const NamedDecl *D) {
           return false;
 
         if (const Expr *Init = VD->getInit()) {
+          if (const ExprWithCleanups *Cleanups = dyn_cast<ExprWithCleanups>(Init))
+            Init = Cleanups->getSubExpr();
           const CXXConstructExpr *Construct =
             dyn_cast<CXXConstructExpr>(Init);
           if (Construct && !Construct->isElidable()) {

clang/test/SemaCXX/warn-unused-variables.cpp

@@ -123,3 +123,15 @@ namespace PR11550 {
     S3 z = a; // expected-warning {{unused variable 'z'}}
   }
 }
+
+namespace ctor_with_cleanups {
+  struct S1 {
+    ~S1();
+  };
+  struct S2 {
+    S2(const S1&);
+  };
+  void func() {
+    S2 s((S1()));
+  }
+}