As Eli pointed out, it is possible that a namespace lookup is ambiguous!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@67932 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 7 insertions, 2 deletions

diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index 7f8a69e5f3..67c8777e34 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -1627,7 +1627,6 @@ Sema::DeclTy *Sema::ActOnUsingDirective(Scope *S,
   // Lookup namespace name.
   LookupResult R = LookupParsedName(S, &SS, NamespcName,
                                     LookupNamespaceName, false);
-  // FIXME: Can the result of a namespace lookup ever be ambiguous?
   if (R.isAmbiguous()) {
     DiagnoseAmbiguousLookup(R, NamespcName, IdentLoc);
     return 0;
@@ -1697,7 +1696,6 @@ Sema::DeclTy *Sema::ActOnNamespaceAliasDef(Scope *S,
   // Lookup the namespace name.
   LookupResult R = LookupParsedName(S, &SS, NamespaceName,
                                     LookupNamespaceName, false);
-  // FIXME: Can the result of a namespace lookup ever be ambiguous?
   if (R.isAmbiguous()) {
     DiagnoseAmbiguousLookup(R, NamespaceName, NamespaceLoc);
     return 0;
diff --git a/test/SemaCXX/namespace-alias.cpp b/test/SemaCXX/namespace-alias.cpp
index 7d46d08678..b05db5ffe0 100644
--- a/test/SemaCXX/namespace-alias.cpp
+++ b/test/SemaCXX/namespace-alias.cpp
@@ -14,3 +14,10 @@ int i;
 namespace D = i; // expected-error {{expected namespace name}}
 
 namespace E = N::Foo; // expected-error {{expected namespace name}}
+
+namespace F {
+  namespace A { namespace B { } } // expected-note {{candidate found by name lookup is 'F::A::B'}}
+  namespace B { } // expected-note {{candidate found by name lookup is 'F::B'}}
+  using namespace A;
+  namespace D = B; // expected-error {{reference to 'B' is ambiguous}}
+}