Fix structural inequivalency of forward EnumDecl

Summary:
Currently we consider one forward declared RecordDecl and another with a
definition equal. We have to do the same in case of enums.

Reviewers: a_sidorin, r.stahl, xazax.hun

Subscribers: rnkovacs, dkrupp, cfe-commits

Differential Revision: https://reviews.llvm.org/D50444

llvm-svn: 339336

1 files changed, 8 insertions, 0 deletions

diff --git a/clang/lib/AST/ASTStructuralEquivalence.cpp b/clang/lib/AST/ASTStructuralEquivalence.cpp
index 7fc3239b03d..1a3fb4063b9 100644
--- a/clang/lib/AST/ASTStructuralEquivalence.cpp
+++ b/clang/lib/AST/ASTStructuralEquivalence.cpp
@@ -1178,6 +1178,14 @@ static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
 /// Determine structural equivalence of two enums.
 static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
                                      EnumDecl *D1, EnumDecl *D2) {
+
+  // Compare the definitions of these two enums. If either or both are
+  // incomplete (i.e. forward declared), we assume that they are equivalent.
+  D1 = D1->getDefinition();
+  D2 = D2->getDefinition();
+  if (!D1 || !D2)
+    return true;
+
   EnumDecl::enumerator_iterator EC2 = D2->enumerator_begin(),
                                 EC2End = D2->enumerator_end();
   for (EnumDecl::enumerator_iterator EC1 = D1->enumerator_begin(),