From caa02f879f569de2c0d912e670f0edbb647ed3a4 Mon Sep 17 00:00:00 2001
From: Will Wilson <will@indefiant.com>
Date: Thu, 25 Oct 2018 11:45:32 +0000
Subject: [PATCH] [ms] Prevent explicit constructor name lookup if scope is
 missing

MicrosoftExt allows explicit constructor calls. Prevent lookup of constructor name unless the name has explicit scope.
This avoids a compile-time crash due to confusing a member access for a constructor name.

Test case included. All tests pass.

Differential Revision: https://reviews.llvm.org/D53441

llvm-svn: 345258
---
 clang/lib/Parse/ParseExpr.cpp                 |  3 ++-
 clang/test/SemaCXX/MicrosoftCompatibility.cpp | 20 ++++++++++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/clang/lib/Parse/ParseExpr.cpp b/clang/lib/Parse/ParseExpr.cpp
index b9028bf..54733d8 100644
--- a/clang/lib/Parse/ParseExpr.cpp
+++ b/clang/lib/Parse/ParseExpr.cpp
@@ -1809,7 +1809,8 @@ Parser::ParsePostfixExpressionSuffix(ExprResult LHS) {
                                     /*EnteringContext=*/false,
                                     /*AllowDestructorName=*/true,
                                     /*AllowConstructorName=*/
-                                      getLangOpts().MicrosoftExt,
+                                    getLangOpts().MicrosoftExt &&
+                                        SS.isNotEmpty(),
                                     /*AllowDeductionGuide=*/false,
                                     ObjectType, &TemplateKWLoc, Name)) {
         (void)Actions.CorrectDelayedTyposInExpr(LHS);
diff --git a/clang/test/SemaCXX/MicrosoftCompatibility.cpp b/clang/test/SemaCXX/MicrosoftCompatibility.cpp
index 203a810..727e675 100644
--- a/clang/test/SemaCXX/MicrosoftCompatibility.cpp
+++ b/clang/test/SemaCXX/MicrosoftCompatibility.cpp
@@ -302,3 +302,23 @@ void function_to_voidptr_conv() {
   void *a2 = &function_prototype; // expected-warning {{implicit conversion between pointer-to-function and pointer-to-object is a Microsoft extension}}
   void *a3 = function_ptr;        // expected-warning {{implicit conversion between pointer-to-function and pointer-to-object is a Microsoft extension}}
 }
+
+namespace member_lookup {
+
+template<typename T>
+struct ConfuseLookup {
+  T* m_val;
+  struct m_val {
+    static size_t ms_test;
+  };
+};
+
+// Microsoft mode allows explicit constructor calls
+// This could confuse name lookup in cases such as this
+template<typename T>
+size_t ConfuseLookup<T>::m_val::ms_test
+  = size_t(&(char&)(reinterpret_cast<ConfuseLookup<T>*>(0)->m_val));
+
+void instantiate() { ConfuseLookup<int>::m_val::ms_test = 1; }
+}
+
-- 
2.7.4