r316965 - [modules] Retain multiple using-directives in the same scope even if they name the same namespace.

[Richard Smith via cfe-commits]

Author: rsmith
Date: Mon Oct 30 15:38:20 2017
New Revision: 316965

URL: http://llvm.org/viewvc/llvm-project?rev=316965&view=rev
Log:
[modules] Retain multiple using-directives in the same scope even if they name the same namespace.

They might have different visibility, and thus discarding all but one of them
can result in rejecting valid code. Also fix name lookup to cope with multiple
using-directives being found that denote the same namespace, where some are not
visible -- don't cache an "already visited" state for a using-directive that we
didn't visit because it was hidden.

Added:
    cfe/trunk/test/Modules/using-directive-redecl.cpp
Modified:
    cfe/trunk/lib/AST/Decl.cpp
    cfe/trunk/lib/Sema/SemaLookup.cpp

Modified: cfe/trunk/lib/AST/Decl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/Decl.cpp?rev=316965&r1=316964&r2=316965&view=diff
==============================================================================
--- cfe/trunk/lib/AST/Decl.cpp (original)
+++ cfe/trunk/lib/AST/Decl.cpp Mon Oct 30 15:38:20 2017
@@ -1597,14 +1597,6 @@ bool NamedDecl::declarationReplaces(Name
                         cast<UnresolvedUsingValueDecl>(OldD)->getQualifier());
   }
 
-  // UsingDirectiveDecl's are not really NamedDecl's, and all have same name.
-  // They can be replaced if they nominate the same namespace.
-  // FIXME: Is this true even if they have different module visibility?
-  if (auto *UD = dyn_cast<UsingDirectiveDecl>(this))
-    return UD->getNominatedNamespace()->getOriginalNamespace() ==
-           cast<UsingDirectiveDecl>(OldD)->getNominatedNamespace()
-               ->getOriginalNamespace();
-
   if (isRedeclarable(getKind())) {
     if (getCanonicalDecl() != OldD->getCanonicalDecl())
       return false;

Modified: cfe/trunk/lib/Sema/SemaLookup.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaLookup.cpp?rev=316965&r1=316964&r2=316965&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaLookup.cpp (original)
+++ cfe/trunk/lib/Sema/SemaLookup.cpp Mon Oct 30 15:38:20 2017
@@ -155,7 +155,7 @@ namespace {
       while (true) {
         for (auto UD : DC->using_directives()) {
           DeclContext *NS = UD->getNominatedNamespace();
-          if (visited.insert(NS).second && SemaRef.isVisible(UD)) {
+          if (SemaRef.isVisible(UD) && visited.insert(NS).second) {
             addUsingDirective(UD, EffectiveDC);
             queue.push_back(NS);
           }
@@ -1883,7 +1883,7 @@ static bool LookupQualifiedNameInUsingDi
   // with its using-children.
   for (auto *I : StartDC->using_directives()) {
     NamespaceDecl *ND = I->getNominatedNamespace()->getOriginalNamespace();
-    if (Visited.insert(ND).second && S.isVisible(I))
+    if (S.isVisible(I) && Visited.insert(ND).second)
       Queue.push_back(ND);
   }
 
@@ -1931,7 +1931,7 @@ static bool LookupQualifiedNameInUsingDi
 
     for (auto I : ND->using_directives()) {
       NamespaceDecl *Nom = I->getNominatedNamespace();
-      if (Visited.insert(Nom).second && S.isVisible(I))
+      if (S.isVisible(I) && Visited.insert(Nom).second)
         Queue.push_back(Nom);
     }
   }

Added: cfe/trunk/test/Modules/using-directive-redecl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Modules/using-directive-redecl.cpp?rev=316965&view=auto
==============================================================================
--- cfe/trunk/test/Modules/using-directive-redecl.cpp (added)
+++ cfe/trunk/test/Modules/using-directive-redecl.cpp Mon Oct 30 15:38:20 2017
@@ -0,0 +1,37 @@
+// RUN: %clang_cc1 -fmodules -fmodules-local-submodule-visibility -verify %s
+// expected-no-diagnostics
+#pragma clang module build M
+module M { module TDFNodes {} module TDFInterface {} }
+#pragma clang module contents
+  // TDFNodes
+  #pragma clang module begin M.TDFNodes
+  namespace Detail {
+     namespace TDF {
+        class TLoopManager {};
+     }
+  }
+  namespace Internal {
+     namespace TDF {
+        using namespace Detail::TDF;
+     }
+  }
+  #pragma clang module end
+
+  // TDFInterface
+  #pragma clang module begin M.TDFInterface
+    #pragma clang module import M.TDFNodes
+      namespace Internal {
+        namespace TDF {
+          using namespace Detail::TDF;
+        }
+      }
+  #pragma clang module end
+
+#pragma clang module endbuild
+
+#pragma clang module import M.TDFNodes
+namespace Internal {
+  namespace TDF {
+    TLoopManager * use;
+  }
+}