[Modules TS] Module ownership semantics for redeclarations.

When declaring an entity in the "purview" of a module, it's never a
redeclaration of an entity in the purview of a default module or in no module
("in the global module"). Don't consider those other declarations as possible
redeclaration targets if they're not visible, and reject any cases where we
pick a prior visible declaration that violates this rule.

This reinstates r315251 and r315256, reverted in r315309 and r315308
respectively, tweaked to avoid triggering a linkage calculation when declaring
implicit special members (this exposed our pre-existing issue with typedef
names for linkage changing the linkage of types whose linkage has already been
computed and cached in more cases). A testcase for that regression has been
added in r315366.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@315379 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 2 insertions, 3 deletions

diff --git a/lib/AST/DeclBase.cpp b/lib/AST/DeclBase.cpp
index 42f0ba0bd7..1e15ee98bb 100644
--- a/lib/AST/DeclBase.cpp
+++ b/lib/AST/DeclBase.cpp
@@ -315,12 +315,11 @@ bool Decl::isLexicallyWithinFunctionOrMethod() const {
 }
 
 bool Decl::isInAnonymousNamespace() const {
-  const DeclContext *DC = getDeclContext();
-  do {
+  for (const DeclContext *DC = getDeclContext(); DC; DC = DC->getParent()) {
     if (const NamespaceDecl *ND = dyn_cast<NamespaceDecl>(DC))
       if (ND->isAnonymousNamespace())
         return true;
-  } while ((DC = DC->getParent()));
+  }
 
   return false;
 }