Add a fix-it and better error recovery for improperly nested namespaces. This will give a better error message for cases such as "namespace foo::bar::baz {}" and a suggested fix-it of "namespace foo { namespace bar { namespace baz {} } }"

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@132138 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Basic/DiagnosticParseKinds.td

@@ -161,6 +161,8 @@ def err_unexpected_namespace_attributes_alias : Error<
 def err_inline_namespace_alias : Error<"namespace alias cannot be inline">;
 def err_namespace_nonnamespace_scope : Error<
   "namespaces can only be defined in global or namespace scope">;
+def err_nested_namespaces_with_double_colon : Error<
+  "nested namespace definition must define each namespace separately">;
 def err_expected_semi_after_attribute_list : Error<
   "expected ';' after attribute list">;
 def err_expected_semi_after_static_assert : Error<

include/clang/Parse/Parser.h

@@ -1720,6 +1720,12 @@ bool ParseAsmOperandsOpt(llvm::SmallVectorImpl<IdentifierInfo *> &Names,
   
   Decl *ParseNamespace(unsigned Context, SourceLocation &DeclEnd,
                        SourceLocation InlineLoc = SourceLocation());
+  void ParseInnerNamespace(std::vector<SourceLocation>& IdentLoc,
+                           std::vector<IdentifierInfo*>& Ident,
+                           std::vector<SourceLocation>& NamespaceLoc,
+                           unsigned int index, SourceLocation& InlineLoc,
+                           SourceLocation& LBrace, ParsedAttributes& attrs,
+                           SourceLocation& RBraceLoc);
   Decl *ParseLinkage(ParsingDeclSpec &DS, unsigned Context);
   Decl *ParseUsingDirectiveOrDeclaration(unsigned Context,
                                          const ParsedTemplateInfo &TemplateInfo,

lib/Parse/ParseDeclCXX.cpp

@@ -60,12 +60,20 @@ Decl *Parser::ParseNamespace(unsigned Context,
 
   SourceLocation IdentLoc;
   IdentifierInfo *Ident = 0;
+  std::vector<SourceLocation> ExtraIdentLoc;
+  std::vector<IdentifierInfo*> ExtraIdent;
+  std::vector<SourceLocation> ExtraNamespaceLoc;
 
   Token attrTok;
 
   if (Tok.is(tok::identifier)) {
     Ident = Tok.getIdentifierInfo();
     IdentLoc = ConsumeToken();  // eat the identifier.
+    while (Tok.is(tok::coloncolon) && NextToken().is(tok::identifier)) {
+      ExtraNamespaceLoc.push_back(ConsumeToken());
+      ExtraIdent.push_back(Tok.getIdentifierInfo());
+      ExtraIdentLoc.push_back(ConsumeToken());
+    }
   }
 
   // Read label attributes, if present.
@@ -85,7 +93,12 @@ Decl *Parser::ParseNamespace(unsigned Context,
     return ParseNamespaceAlias(NamespaceLoc, IdentLoc, Ident, DeclEnd);
   }
 
+
   if (Tok.isNot(tok::l_brace)) {
+    if (!ExtraIdent.empty()) {
+      Diag(ExtraNamespaceLoc[0], diag::err_nested_namespaces_with_double_colon)
+          << SourceRange(ExtraNamespaceLoc.front(), ExtraIdentLoc.back());
+    }
     Diag(Tok, Ident ? diag::err_expected_lbrace :
          diag::err_expected_ident_lbrace);
     return 0;
@@ -96,11 +109,44 @@ Decl *Parser::ParseNamespace(unsigned Context,
   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(LBrace, diag::err_namespace_nonnamespace_scope);
     SkipUntil(tok::r_brace, false);
     return 0;
   }
 
+  if (!ExtraIdent.empty()) {
+    TentativeParsingAction TPA(*this);
+    SkipUntil(tok::r_brace, /*StopAtSemi*/false, /*DontConsume*/true);
+    Token rBraceToken = Tok;
+    TPA.Revert();
+
+    if (!rBraceToken.is(tok::r_brace)) {
+      Diag(ExtraNamespaceLoc[0], diag::err_nested_namespaces_with_double_colon)
+          << SourceRange(ExtraNamespaceLoc.front(), ExtraIdentLoc.back());
+    } else {
+
+      std::string NamespaceFix = "";
+      for (std::vector<IdentifierInfo*>::iterator I = ExtraIdent.begin(),
+           E = ExtraIdent.end(); I != E; ++I) {
+        NamespaceFix += " { namespace ";
+        NamespaceFix += (*I)->getName();
+      }
+      std::string RBraces;
+      for (int i = 0; i < ExtraIdent.size(); ++i) {
+        RBraces +=  "} ";
+      }
+      Diag(ExtraNamespaceLoc[0], diag::err_nested_namespaces_with_double_colon)
+          << FixItHint::CreateReplacement(SourceRange(ExtraNamespaceLoc.front(),
+                                                      ExtraIdentLoc.back()),
+                                          NamespaceFix)
+          << FixItHint::CreateInsertion(rBraceToken.getLocation(), RBraces);
+    }
+  }
+
   // If we're still good, complain about inline namespaces in non-C++0x now.
   if (!getLang().CPlusPlus0x && InlineLoc.isValid())
     Diag(InlineLoc, diag::ext_inline_namespace);
@@ -115,23 +161,56 @@ Decl *Parser::ParseNamespace(unsigned Context,
   PrettyDeclStackTraceEntry CrashInfo(Actions, NamespcDecl, NamespaceLoc,
                                       "parsing namespace");
 
-  while (Tok.isNot(tok::r_brace) && Tok.isNot(tok::eof)) {
-    ParsedAttributesWithRange attrs(AttrFactory);
-    MaybeParseCXX0XAttributes(attrs);
-    MaybeParseMicrosoftAttributes(attrs);
-    ParseExternalDeclaration(attrs);
-  }
+  SourceLocation RBraceLoc;
+  // Parse the contents of the namespace.  This includes parsing recovery on 
+  // any improperly nested namespaces.
+  ParseInnerNamespace(ExtraIdentLoc, ExtraIdent, ExtraNamespaceLoc, 0,
+                      InlineLoc, LBrace, attrs, RBraceLoc);
 
   // Leave the namespace scope.
   NamespaceScope.Exit();
 
-  SourceLocation RBraceLoc = MatchRHSPunctuation(tok::r_brace, LBrace);
   Actions.ActOnFinishNamespaceDef(NamespcDecl, RBraceLoc);
 
   DeclEnd = RBraceLoc;
   return NamespcDecl;
 }
 
+/// 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,
+                                 SourceLocation& LBrace,
+                                 ParsedAttributes& attrs,
+                                 SourceLocation& RBraceLoc) {
+  if (index == Ident.size()) {
+    while (Tok.isNot(tok::r_brace) && Tok.isNot(tok::eof)) {
+      ParsedAttributesWithRange attrs(AttrFactory);
+      MaybeParseCXX0XAttributes(attrs);
+      MaybeParseMicrosoftAttributes(attrs);
+      ParseExternalDeclaration(attrs);
+    }
+    RBraceLoc = MatchRHSPunctuation(tok::r_brace, LBrace);
+
+    return;
+  }
+
+  // Parse improperly nested namespaces.
+  ParseScope NamespaceScope(this, Scope::DeclScope);
+  Decl *NamespcDecl =
+    Actions.ActOnStartNamespaceDef(getCurScope(), SourceLocation(),
+                                   NamespaceLoc[index], IdentLoc[index],
+                                   Ident[index], LBrace, attrs.getList());
+
+  ParseInnerNamespace(IdentLoc, Ident, NamespaceLoc, ++index, InlineLoc,
+                      LBrace, attrs, RBraceLoc);
+
+  NamespaceScope.Exit();
+
+  Actions.ActOnFinishNamespaceDef(NamespcDecl, RBraceLoc);
+}
+
 /// ParseNamespaceAlias - Parse the part after the '=' in a namespace
 /// alias definition.
 ///

test/Parser/nested-namespaces-recovery.cpp

@@ -0,0 +1,24 @@
+// RUN: cp %s %t
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+// RUN: not %clang_cc1 -x c++ -fixit %t
+// RUN: %clang_cc1 -x c++ %t
+
+namespace foo1::foo2::foo3 { // expected-error {{nested namespace definition must define each namespace separately}}
+  int foo(int x) { return x; }
+}
+
+int foo(int x) {
+  return foo1::foo2::foo3::foo(x);
+}
+
+namespace bar1 {
+  namespace bar2 {
+    namespace bar3 {
+      int bar(int x) { return x; }
+    }
+  }
+}
+
+int bar(int x) {
+  return bar1::bar2::bar3::bar(x);
+}