Improve diagnostic when failing to synthesize implicit member due to dllexport (PR22591)

This is only a problem in C++03 mode targeting MS ABI (MinGW doesn't
export inline methods, and C++11 marks these methods implicitly
deleted).

Since targeting the MS ABI in pre-C++11 mode is a rare configuration,
this will probably not get fixed, but we can at least have a better
error message.

llvm-svn: 230115

1 files changed, 6 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 33f8c91691f..4d2e87798fb 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -4821,7 +4821,13 @@ static void checkDLLAttribute(Sema &S, CXXRecordDecl *Class) {
         // defaulted methods, and the copy and move assignment operators. The
         // latter are exported even if they are trivial, because the address of
         // an operator can be taken and should compare equal accross libraries.
+        DiagnosticErrorTrap Trap(S.Diags);
         S.MarkFunctionReferenced(Class->getLocation(), MD);
+        if (Trap.hasErrorOccurred()) {
+          S.Diag(ClassAttr->getLocation(), diag::note_due_to_dllexported_class)
+              << Class->getName() << !S.getLangOpts().CPlusPlus11;
+          break;
+        }
 
         // There is no later point when we will see the definition of this
         // function, so pass it to the consumer now.