1 files changed, 18 insertions, 19 deletions

diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index e5cf84a74f9..223046c90d9 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -110,39 +110,36 @@ Decl *Parser::ParseNamespace(unsigned Context,
 
   BalancedDelimiterTracker T(*this, tok::l_brace);
   if (T.consumeOpen()) {
-    if (!ExtraIdent.empty()) {
-      Diag(ExtraNamespaceLoc[0], diag::err_nested_namespaces_with_double_colon)
-          << SourceRange(ExtraNamespaceLoc.front(), ExtraIdentLoc.back());
-    }
-
     if (Ident)
       Diag(Tok, diag::err_expected) << tok::l_brace;
     else
       Diag(Tok, diag::err_expected_either) << tok::identifier << tok::l_brace;
-
     return nullptr;
   }
 
   if (getCurScope()->isClassScope() || getCurScope()->isTemplateParamScope() || 
       getCurScope()->isInObjcMethodScope() || getCurScope()->getBlockParent() || 
       getCurScope()->getFnParent()) {
-    if (!ExtraIdent.empty()) {
-      Diag(ExtraNamespaceLoc[0], diag::err_nested_namespaces_with_double_colon)
-          << SourceRange(ExtraNamespaceLoc.front(), ExtraIdentLoc.back());
-    }
     Diag(T.getOpenLocation(), diag::err_namespace_nonnamespace_scope);
     SkipUntil(tok::r_brace);
     return nullptr;
   }
 
-  if (!ExtraIdent.empty()) {
+  if (ExtraIdent.empty()) {
+    // Normal namespace definition, not a nested-namespace-definition.
+  } else if (InlineLoc.isValid()) {
+    Diag(InlineLoc, diag::err_inline_nested_namespace_definition);
+  } else if (getLangOpts().CPlusPlus1z) {
+    Diag(ExtraNamespaceLoc[0],
+         diag::warn_cxx14_compat_nested_namespace_definition);
+  } else {
     TentativeParsingAction TPA(*this);
     SkipUntil(tok::r_brace, StopBeforeMatch);
     Token rBraceToken = Tok;
     TPA.Revert();
 
     if (!rBraceToken.is(tok::r_brace)) {
-      Diag(ExtraNamespaceLoc[0], diag::err_nested_namespaces_with_double_colon)
+      Diag(ExtraNamespaceLoc[0], diag::ext_nested_namespace_definition)
           << SourceRange(ExtraNamespaceLoc.front(), ExtraIdentLoc.back());
     } else {
       std::string NamespaceFix;
@@ -156,7 +153,7 @@ Decl *Parser::ParseNamespace(unsigned Context,
       for (unsigned i = 0, e = ExtraIdent.size(); i != e; ++i)
         RBraces +=  "} ";
 
-      Diag(ExtraNamespaceLoc[0], diag::err_nested_namespaces_with_double_colon)
+      Diag(ExtraNamespaceLoc[0], diag::ext_nested_namespace_definition)
           << FixItHint::CreateReplacement(SourceRange(ExtraNamespaceLoc.front(),
                                                       ExtraIdentLoc.back()),
                                           NamespaceFix)
@@ -195,11 +192,11 @@ Decl *Parser::ParseNamespace(unsigned Context,
 }
 
 /// ParseInnerNamespace - Parse the contents of a namespace.
-void Parser::ParseInnerNamespace(std::vector<SourceLocation>& IdentLoc,
-                                 std::vector<IdentifierInfo*>& Ident,
-                                 std::vector<SourceLocation>& NamespaceLoc,
-                                 unsigned int index, SourceLocation& InlineLoc,
-                                 ParsedAttributes& attrs,
+void Parser::ParseInnerNamespace(std::vector<SourceLocation> &IdentLoc,
+                                 std::vector<IdentifierInfo *> &Ident,
+                                 std::vector<SourceLocation> &NamespaceLoc,
+                                 unsigned int index, SourceLocation &InlineLoc,
+                                 ParsedAttributes &attrs,
                                  BalancedDelimiterTracker &Tracker) {
   if (index == Ident.size()) {
     while (Tok.isNot(tok::r_brace) && !isEofOrEom()) {
@@ -216,7 +213,9 @@ void Parser::ParseInnerNamespace(std::vector<SourceLocation>& IdentLoc,
     return;
   }
 
-  // Parse improperly nested namespaces.
+  // Handle a nested namespace definition.
+  // FIXME: Preserve the source information through to the AST rather than
+  // desugaring it here.
   ParseScope NamespaceScope(this, Scope::DeclScope);
   Decl *NamespcDecl =
     Actions.ActOnStartNamespaceDef(getCurScope(), SourceLocation(),