From 23756776eadfd8bbddf5d120d4c191ef9e50d209 Mon Sep 17 00:00:00 2001
From: Richard Smith <richard-llvm@metafoo.co.uk>
Date: Mon, 14 May 2012 22:43:34 +0000
Subject: [PATCH] Recover properly from a redundant 'typename' before a
 non-nested name. This is permitted as a Microsoft extension. Patch by William
 Wilson! (Plus some minor tweaking by me.)

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@156786 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Parse/Parser.cpp                | 22 +++++++++++++++++-----
 test/Parser/MicrosoftExtensions.cpp | 13 +++++++++++++
 2 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/lib/Parse/Parser.cpp b/lib/Parse/Parser.cpp
index 955f4558f8..ad283fa57a 100644
--- a/lib/Parse/Parser.cpp
+++ b/lib/Parse/Parser.cpp
@@ -1248,7 +1248,8 @@ TemplateIdAnnotation *Parser::takeTemplateIdAnnotation(const Token &tok) {
 bool Parser::TryAnnotateTypeOrScopeToken(bool EnteringContext, bool NeedType) {
   assert((Tok.is(tok::identifier) || Tok.is(tok::coloncolon)
           || Tok.is(tok::kw_typename) || Tok.is(tok::annot_cxxscope)
-          || Tok.is(tok::kw_decltype)) && "Cannot be a type or scope token!");
+          || Tok.is(tok::kw_decltype) || Tok.is(tok::annot_template_id))
+          && "Cannot be a type or scope token!");
 
   if (Tok.is(tok::kw_typename)) {
     // Parse a C++ typename-specifier, e.g., "typename T::type".
@@ -1264,10 +1265,21 @@ bool Parser::TryAnnotateTypeOrScopeToken(bool EnteringContext, bool NeedType) {
                                        0, /*IsTypename*/true))
       return true;
     if (!SS.isSet()) {
-      if (getLangOpts().MicrosoftExt)
-        Diag(Tok.getLocation(), diag::warn_expected_qualified_after_typename);
-      else
-        Diag(Tok.getLocation(), diag::err_expected_qualified_after_typename);
+      if (Tok.is(tok::identifier) || Tok.is(tok::annot_template_id)) {
+        // Attempt to recover by skipping the invalid 'typename'
+        if (!TryAnnotateTypeOrScopeToken(EnteringContext, NeedType) &&
+            Tok.isAnnotation()) {
+          unsigned DiagID = diag::err_expected_qualified_after_typename;
+          // MS compatibility: MSVC permits using known types with typename.
+          // e.g. "typedef typename T* pointer_type"
+          if (getLangOpts().MicrosoftExt)
+            DiagID = diag::warn_expected_qualified_after_typename;
+          Diag(Tok.getLocation(), DiagID);
+          return false;
+        }
+      }
+
+      Diag(Tok.getLocation(), diag::err_expected_qualified_after_typename);
       return true;
     }
 
diff --git a/test/Parser/MicrosoftExtensions.cpp b/test/Parser/MicrosoftExtensions.cpp
index 3a1ffea453..351fa73588 100644
--- a/test/Parser/MicrosoftExtensions.cpp
+++ b/test/Parser/MicrosoftExtensions.cpp
@@ -151,11 +151,24 @@ void missing_template_keyword(){
 
 class AAAA { };
 
+template <typename T>
+class SimpleTemplate {};
+
 template <class T>
 void redundant_typename() {
    typename T t;// expected-warning {{expected a qualified name after 'typename'}}
    typename AAAA a;// expected-warning {{expected a qualified name after 'typename'}}
+
    t = 3;
+   
+   typedef typename T* pointerT;// expected-warning {{expected a qualified name after 'typename'}}
+   typedef typename SimpleTemplate<int> templateT;// expected-warning {{expected a qualified name after 'typename'}}
+
+   pointerT pT = &t;
+   *pT = 4;
+
+   int var;
+   int k = typename var;// expected-error {{expected a qualified name after 'typename'}}
 }
 
 
-- 
2.40.0