Typedefs can be redeclared. That seems like something we should record in

the AST lest we run into some crazy canonicalization bug like PR5874.

llvm-svn: 92283

2 files changed, 14 insertions, 3 deletions

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 9ed4fba66e5..0a80f45f43e 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -696,9 +696,8 @@ void Sema::MergeTypeDefDecl(TypedefDecl *New, LookupResult &OldDecls) {
   }
 
   // Verify the old decl was also a type.
-  TypeDecl *Old = 0;
-  if (!OldDecls.isSingleResult() ||
-      !(Old = dyn_cast<TypeDecl>(OldDecls.getFoundDecl()))) {
+  TypeDecl *Old = OldDecls.getAsSingle<TypeDecl>();
+  if (!Old) {
     Diag(New->getLocation(), diag::err_redefinition_different_kind)
       << New->getDeclName();
 
@@ -733,6 +732,13 @@ void Sema::MergeTypeDefDecl(TypedefDecl *New, LookupResult &OldDecls) {
     return New->setInvalidDecl();
   }
 
+  // The types match.  Link up the redeclaration chain if the old
+  // declaration was a typedef.
+  // FIXME: this is a potential source of wierdness if the type
+  // spellings don't match exactly.
+  if (isa<TypedefDecl>(Old))
+    New->setPreviousDeclaration(cast<TypedefDecl>(Old));
+
   if (getLangOptions().Microsoft)
     return;
 
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 1ec91bd55ec..e909c4f0b9b 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -145,6 +145,11 @@ Decl *TemplateDeclInstantiator::VisitTypedefDecl(TypedefDecl *D) {
   if (Invalid)
     Typedef->setInvalidDecl();
 
+  if (TypedefDecl *Prev = D->getPreviousDeclaration()) {
+    NamedDecl *InstPrev = SemaRef.FindInstantiatedDecl(Prev, TemplateArgs);
+    Typedef->setPreviousDeclaration(cast<TypedefDecl>(InstPrev));
+  }
+
   Owner->addDecl(Typedef);
 
   return Typedef;