[ASTImporter] Fix redecl chain of classes and class templates

Summary:
The crux of the issue that is being fixed is that lookup could not find
previous decls of a friend class. The solution involves making the
friend declarations visible in their decl context (i.e. adding them to
the lookup table).
Also, we simplify `VisitRecordDecl` greatly.

This fix involves two other repairs (without these the unittests fail):
(1) We could not handle the addition of injected class types properly
when a redecl chain was involved, now this is fixed.
(2) DeclContext::removeDecl failed if the lookup table in Vector form
did not contain the to be removed element. This caused troubles in
ASTImporter::ImportDeclContext. This is also fixed.

Reviewers: a_sidorin, balazske, a.sidorin

Subscribers: rnkovacs, dkrupp, Szelethus, cfe-commits

Differential Revision: https://reviews.llvm.org/D53655

llvm-svn: 349349

1 files changed, 3 insertions, 1 deletions

diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
index 95babf79179..66dfa53314e 100644
--- a/clang/lib/AST/DeclBase.cpp
+++ b/clang/lib/AST/DeclBase.cpp
@@ -1463,7 +1463,9 @@ void DeclContext::removeDecl(Decl *D) {
       if (Map) {
         StoredDeclsMap::iterator Pos = Map->find(ND->getDeclName());
         assert(Pos != Map->end() && "no lookup entry for decl");
-        if (Pos->second.getAsVector() || Pos->second.getAsDecl() == ND)
+        // Remove the decl only if it is contained.
+        StoredDeclsList::DeclsTy *Vec = Pos->second.getAsVector();
+        if ((Vec && is_contained(*Vec, ND)) || Pos->second.getAsDecl() == ND)
           Pos->second.remove(ND);
       }
     } while (DC->isTransparentContext() && (DC = DC->getParent()));