[MSVC] Crash fix: assigning of overloaded member function pointer caused assertion

[ABataev]

Summary

Original class was not marked with inheritance attribute and it causes a crash on codegen.

[majnemer]

lib/Sema/SemaCast.cpp

1399–1400

There is no need for else if here because the previous if uses return to exit the function: http://llvm.org/docs/CodingStandards.html#don-t-use-else-after-a-return

lib/Sema/SemaType.cpp

6479

This change should be unnecessary because getAs already looks through typedefs: http://clang.llvm.org/doxygen/Type_8h_source.html#l05557

[ABataev]

Update after review

[majnemer]

LGTM

lib/Sema/SemaCast.cpp

if (FunctionDecl *Fn
       WasOverloadedFunction = true;
     }
   }
   
   const MemberPointerType *SrcMemPtr = SrcType->getAs<MemberPointerType>();
   if (!SrcMemPtr) {
     msg = diag::err_bad_static_cast_member_pointer_nonmp;
     return TC_NotApplicable;
-  }
+  } else if (Self.Context.getTargetInfo().getCXXABI().isMicrosoft())
+    Self.RequireCompleteType(OpRange.getBegin(), SrcType, 0);
 
   // T == T, modulo cv
   if (!Self.Context.hasSameUnqualifiedType(SrcMemPtr->getPointeeType(),
                                            DestMemPtr->getPointeeType()))
     return TC_NotApplicable;
 
   // B base of D
   QualType SrcClass(SrcMemPtr->getClass(), 0);

lib/Sema/SemaType.cpp

if (!T->isIncompleteType(&Def)) {
     NamedDecl *SuggestedDef = nullptr;
     if (!Diagnoser.Suppressed && Def &&
         !hasVisibleDefinition(Def, &SuggestedDef, /*OnlyNeedComplete*/true))
       diagnoseMissingImport(Loc, SuggestedDef, /*NeedDefinition*/true);
 
     // We lock in the inheritance model once somebody has asked us to ensure
     // that a pointer-to-member type is complete.
     if (Context.getTargetInfo().getCXXABI().isMicrosoft()) {
-      if (const MemberPointerType *MPTy = T->getAs<MemberPointerType>()) {
+      if (auto *MPTy = T.getCanonicalType()->getAs<MemberPointerType>()) {
         if (!MPTy->getClass()->isDependentType()) {
           RequireCompleteType(Loc, QualType(MPTy->getClass(), 0), 0);
           assignInheritanceModel(*this, MPTy->getMostRecentCXXRecordDecl());
         }
       }
     }
 
     return false;

test/CodeGenCXX/microsoft-abi-member-pointers.cpp

 struct D : A, C {};
 
 typedef void (D::*DMemPtrTy)();
 
 // CHECK-LABEL: define void @"\01?get_memptr@pr23878@@YAP8D@1@AEXXZXZ"
 // CHECK: @"\01??_9C@pr23878@@$BA@AE" to i8*), i32 0, i32 4
 DMemPtrTy get_memptr() { return &D::f; }
 }
+
+class C {};
+
+typedef void (C::*f)();
+
+class CA : public C {
+public:
+  void OnHelp(void);
+  int OnHelp(int);
+};
+
+// CHECK-LABEL: foo_fun
+void foo_fun() {
+  // CHECK: store i8* bitcast (void (%class.CA*)* @"\01?OnHelp@CA@@QAEXXZ" to i8*), i8**
+  f func = (f)&CA::OnHelp;
+}
+