[Sema] ADL: Associated namespaces for class types and enumeration types (CWG 1691)

CWG 1691 changed the definition of the namespaces associated with a class
type or enumeration type.

For a class type, the associated namespaces are the innermost enclosing
namespaces of the associated classes. For an enumeration type, the associated
namespace is the innermost enclosing namespace of its declaration.

This also fixes CWG 1690 and CWG 1692.

Differential Revision: https://reviews.llvm.org/D60573

Reviewed By: rjmccall, rsmith

llvm-svn: 358882

1 files changed, 35 insertions, 27 deletions

diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index c26fbac406b..2b7924d244e 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -2471,30 +2471,38 @@ namespace {
 static void
 addAssociatedClassesAndNamespaces(AssociatedLookup &Result, QualType T);
 
+// Given the declaration context \param Ctx of a class, class template or
+// enumeration, add the associated namespaces to \param Namespaces as described
+// in [basic.lookup.argdep]p2.
 static void CollectEnclosingNamespace(Sema::AssociatedNamespaceSet &Namespaces,
                                       DeclContext *Ctx) {
-  // Add the associated namespace for this class.
-
-  // We don't use DeclContext::getEnclosingNamespaceContext() as this may
-  // be a locally scoped record.
+  // The exact wording has been changed in C++14 as a result of
+  // CWG 1691 (see also CWG 1690 and CWG 1692). We apply it unconditionally
+  // to all language versions since it is possible to return a local type
+  // from a lambda in C++11.
+  //
+  // C++14 [basic.lookup.argdep]p2:
+  //   If T is a class type [...]. Its associated namespaces are the innermost
+  //   enclosing namespaces of its associated classes. [...]
+  //
+  //   If T is an enumeration type, its associated namespace is the innermost
+  //   enclosing namespace of its declaration. [...]
 
-  // We skip out of inline namespaces. The innermost non-inline namespace
+  // We additionally skip inline namespaces. The innermost non-inline namespace
   // contains all names of all its nested inline namespaces anyway, so we can
   // replace the entire inline namespace tree with its root.
-  while (Ctx->isRecord() || Ctx->isTransparentContext() ||
-         Ctx->isInlineNamespace())
+  while (!Ctx->isFileContext() || Ctx->isInlineNamespace())
     Ctx = Ctx->getParent();
 
-  if (Ctx->isFileContext())
-    Namespaces.insert(Ctx->getPrimaryContext());
+  Namespaces.insert(Ctx->getPrimaryContext());
 }
 
 // Add the associated classes and namespaces for argument-dependent
-// lookup that involves a template argument (C++ [basic.lookup.koenig]p2).
+// lookup that involves a template argument (C++ [basic.lookup.argdep]p2).
 static void
 addAssociatedClassesAndNamespaces(AssociatedLookup &Result,
                                   const TemplateArgument &Arg) {
-  // C++ [basic.lookup.koenig]p2, last bullet:
+  // C++ [basic.lookup.argdep]p2, last bullet:
   //   -- [...] ;
   switch (Arg.getKind()) {
     case TemplateArgument::Null:
@@ -2539,9 +2547,8 @@ addAssociatedClassesAndNamespaces(AssociatedLookup &Result,
   }
 }
 
-// Add the associated classes and namespaces for
-// argument-dependent lookup with an argument of class type
-// (C++ [basic.lookup.koenig]p2).
+// Add the associated classes and namespaces for argument-dependent lookup
+// with an argument of class type (C++ [basic.lookup.argdep]p2).
 static void
 addAssociatedClassesAndNamespaces(AssociatedLookup &Result,
                                   CXXRecordDecl *Class) {
@@ -2550,18 +2557,19 @@ addAssociatedClassesAndNamespaces(AssociatedLookup &Result,
   if (Class->getDeclName() == Result.S.VAListTagName)
     return;
 
-  // C++ [basic.lookup.koenig]p2:
+  // C++ [basic.lookup.argdep]p2:
   //   [...]
   //     -- If T is a class type (including unions), its associated
   //        classes are: the class itself; the class of which it is a
-  //        member, if any; and its direct and indirect base
-  //        classes. Its associated namespaces are the namespaces in
-  //        which its associated classes are defined.
+  //        member, if any; and its direct and indirect base classes.
+  //        Its associated namespaces are the innermost enclosing
+  //        namespaces of its associated classes.
 
   // Add the class of which it is a member, if any.
   DeclContext *Ctx = Class->getDeclContext();
   if (CXXRecordDecl *EnclosingClass = dyn_cast<CXXRecordDecl>(Ctx))
     Result.Classes.insert(EnclosingClass);
+
   // Add the associated namespace for this class.
   CollectEnclosingNamespace(Result.Namespaces, Ctx);
 
@@ -2682,10 +2690,10 @@ addAssociatedClassesAndNamespaces(AssociatedLookup &Result, QualType Ty) {
       break;
 
     //     -- If T is a class type (including unions), its associated
-    //        classes are: the class itself; the class of which it is a
-    //        member, if any; and its direct and indirect base
-    //        classes. Its associated namespaces are the namespaces in
-    //        which its associated classes are defined.
+    //        classes are: the class itself; the class of which it is
+    //        a member, if any; and its direct and indirect base classes.
+    //        Its associated namespaces are the innermost enclosing
+    //        namespaces of its associated classes.
     case Type::Record: {
       CXXRecordDecl *Class =
           cast<CXXRecordDecl>(cast<RecordType>(T)->getDecl());
@@ -2693,10 +2701,10 @@ addAssociatedClassesAndNamespaces(AssociatedLookup &Result, QualType Ty) {
       break;
     }
 
-    //     -- If T is an enumeration type, its associated namespace is
-    //        the namespace in which it is defined. If it is class
-    //        member, its associated class is the member's class; else
-    //        it has no associated class.
+    //     -- If T is an enumeration type, its associated namespace
+    //        is the innermost enclosing namespace of its declaration.
+    //        If it is a class member, its associated class is the
+    //        member’s class; else it has no associated class.
     case Type::Enum: {
       EnumDecl *Enum = cast<EnumType>(T)->getDecl();
 
@@ -2704,7 +2712,7 @@ addAssociatedClassesAndNamespaces(AssociatedLookup &Result, QualType Ty) {
       if (CXXRecordDecl *EnclosingClass = dyn_cast<CXXRecordDecl>(Ctx))
         Result.Classes.insert(EnclosingClass);
 
-      // Add the associated namespace for this class.
+      // Add the associated namespace for this enumeration.
       CollectEnclosingNamespace(Result.Namespaces, Ctx);
 
       break;