Adding support for warning when a non-C compatible user-defined type is returned from an extern "C" function.

Fixes bug 6143

llvm-svn: 150128

1 files changed, 11 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index ed8d8a5d71b..3d24c592914 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -5774,6 +5774,17 @@ bool Sema::CheckFunctionDeclaration(Scope *S, FunctionDecl *NewFD,
         Context.BuiltinInfo.ForgetBuiltin(BuiltinID, Context.Idents);
       }
     }
+  
+    // If this function is declared as being extern "C", then check to see if 
+    // the function returns a UDT (class, struct, or union type) that is not C
+    // compatible, and if it does, warn the user.
+    if (NewFD->isExternC()) {
+      QualType R = NewFD->getResultType();
+      if (!R.isPODType(Context) && 
+          !R->isVoidType())
+        Diag( NewFD->getLocation(), diag::warn_return_value_udt ) 
+          << NewFD << R;
+    }
   }
   return Redeclaration;
 }