In Microsoft mode, make "Unqualified lookup into dependent bases of class templates" works inside default argument instantiation.

This is a little bit tricky because during default argument instantiation the CurContext points to a CXXMethodDecl but we can't use the keyword this or have an implicit member call generated.

This fixes 2 errors when parsing MFC code with clang.

llvm-svn: 144881

clang/lib/Sema/SemaExpr.cpp

@@ -1520,10 +1520,17 @@ bool Sema::DiagnoseEmptyLookup(Scope *S, CXXScopeSpec &SS, LookupResult &R,
         // Don't give errors about ambiguities in this lookup.
         R.suppressDiagnostics();
 
+        // During a default argument instantiation the CurContext points
+        // to a CXXMethodDecl; but we can't apply a this-> fixit inside a
+        // function parameter list, hence add an explicit check.
+        bool isDefaultArgument = !ActiveTemplateInstantiations.empty() &&
+                              ActiveTemplateInstantiations.back().Kind ==
+            ActiveTemplateInstantiation::DefaultFunctionArgumentInstantiation;
         CXXMethodDecl *CurMethod = dyn_cast<CXXMethodDecl>(CurContext);
         bool isInstance = CurMethod &&
                           CurMethod->isInstance() &&
-                          DC == CurMethod->getParent();
+                          DC == CurMethod->getParent() && !isDefaultArgument;
+                          
 
         // Give a code modification hint to insert 'this->'.
         // TODO: fixit for inserting 'Base<T>::' in the other cases.
@@ -1569,6 +1576,15 @@ bool Sema::DiagnoseEmptyLookup(Scope *S, CXXScopeSpec &SS, LookupResult &R,
         for (LookupResult::iterator I = R.begin(), E = R.end(); I != E; ++I)
           Diag((*I)->getLocation(), diag::note_dependent_var_use);
 
+        // Return true if we are inside a default argument instantiation
+        // and the found name refers to an instance member function, otherwise
+        // the function calling DiagnoseEmptyLookup will try to create an
+        // implicit member call and this is wrong for default argument.
+        if (isDefaultArgument && ((*R.begin())->isCXXInstanceMember())) {
+          Diag(R.getNameLoc(), diag::err_member_call_without_object);
+          return true;
+        }
+
         // Tell the callee to try to recover.
         return false;
       }

clang/lib/Sema/SemaOverload.cpp

@@ -8712,7 +8712,7 @@ Sema::BuildOverloadedCallExpr(Scope *S, Expr *Fn, UnresolvedLookupExpr *ULE,
     // to instantiation time to be able to search into type dependent base
     // classes.
     if (getLangOptions().MicrosoftMode && CurContext->isDependentContext() && 
-        isa<CXXMethodDecl>(CurContext)) {
+        (isa<CXXMethodDecl>(CurContext) || isa<CXXRecordDecl>(CurContext))) {
       CallExpr *CE = new (Context) CallExpr(Context, Fn, Args, NumArgs,
                                           Context.DependentTy, VK_RValue,
                                           RParenLoc);

clang/test/SemaTemplate/ms-lookup-template-base-classes.cpp

@@ -65,9 +65,36 @@ class B : public A<T> {
 public:
   static void z2(){
     static_func();  // expected-warning {{use of identifier 'static_func' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}}
-	  func(); // expected-warning {{use of identifier 'func' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}} expected-error {{call to non-static member function without an object argument}}
+    func(); // expected-warning {{use of identifier 'func' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}} expected-error {{call to non-static member function without an object argument}}
   }
 };
 template class B<int>; // expected-note {{requested here}}
 
 } 
+
+
+
+namespace lookup_dependent_base_class_default_argument {
+
+template<class T>
+class A {
+public:
+  static int f1(); // expected-note {{must qualify identifier to find this declaration in dependent base class}} 
+  int f2(); // expected-note {{must qualify identifier to find this declaration in dependent base class}} 
+};
+
+template<class T>
+class B : public A<T> {
+public:
+  void g1(int p = f1());// expected-warning {{use of identifier 'f1' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}}
+  void g2(int p = f2());// expected-warning {{use of identifier 'f2' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}} expected-error {{call to non-static member function without an object argument}}
+};
+
+void foo()
+{
+	B<int> b;
+	b.g1(); // expected-note {{required here}}
+	b.g2(); // expected-note {{required here}}
+}
+
+}