[PATCH] D53441: [ms] Prevent explicit constructor name lookup if scope is missing

[Will Wilson via Phabricator via cfe-commits]

lantictac created this revision.
lantictac added a reviewer: rsmith.
lantictac added a project: clang.

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.


Repository:
  rC Clang

https://reviews.llvm.org/D53441

Files:
  lib/Parse/ParseExpr.cpp
  test/SemaCXX/MicrosoftCompatibility.cpp


Index: test/SemaCXX/MicrosoftCompatibility.cpp
===================================================================
--- test/SemaCXX/MicrosoftCompatibility.cpp
+++ test/SemaCXX/MicrosoftCompatibility.cpp
@@ -302,3 +302,23 @@
   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; }
+}
+
Index: lib/Parse/ParseExpr.cpp
===================================================================
--- lib/Parse/ParseExpr.cpp
+++ lib/Parse/ParseExpr.cpp
@@ -1809,7 +1809,8 @@
                                     /*EnteringContext=*/false,
                                     /*AllowDestructorName=*/true,
                                     /*AllowConstructorName=*/
-                                      getLangOpts().MicrosoftExt,
+                                    getLangOpts().MicrosoftExt &&
+                                        SS.isNotEmpty(),
                                     /*AllowDeductionGuide=*/false,
                                     ObjectType, &TemplateKWLoc, Name)) {
         (void)Actions.CorrectDelayedTyposInExpr(LHS);


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