[Attr] Don't print fake MSInheritance argument

[jdenny]

Summary

This was discovered at:

http://lists.llvm.org/pipermail/cfe-commits/Week-of-Mon-20180514/228390.html

[aaron.ballman]

LGTM!

include/clang/Basic/Attr.td

 class VersionArgument<string name, bit opt = 0> : Argument<name, opt>;
 
 // This one's a doozy, so it gets its own special type
 // It can be an unsigned integer, or a type. Either can
 // be dependent.
 class AlignedArgument<string name, bit opt = 0> : Argument<name, opt>;
 
 // A bool argument with a default value
-class DefaultBoolArgument<string name, bit default> : BoolArgument<name, 1> {
+class DefaultBoolArgument<string name, bit default, bit fake = 0>
+    : BoolArgument<name, 1, fake> {
   bit Default = default;
 }
 
 // An integer argument with a default value
 class DefaultIntArgument<string name, int default> : IntArgument<name, 1> {
   int Default = default;
 }
 

 
 def UPtr : TypeAttr {
   let Spellings = [Keyword<"__uptr">];
   let Documentation = [Undocumented];
 }
 
 def MSInheritance : InheritableAttr {
   let LangOpts = [MicrosoftExt];
-  let Args = [DefaultBoolArgument<"BestCase", 1>];
+  let Args = [DefaultBoolArgument<"BestCase", /*default*/1, /*fake*/1>];
   let Spellings = [Keyword<"__single_inheritance">,
                    Keyword<"__multiple_inheritance">,
                    Keyword<"__virtual_inheritance">,
                    Keyword<"__unspecified_inheritance">];
   let AdditionalMembers = [{
   static bool hasVBPtrOffsetField(Spelling Inheritance) {
     return Inheritance == Keyword_unspecified_inheritance;
   }

test/SemaCXX/attr-print.cpp

 // CHECK: char *PR24565() __attribute__((malloc))
 char *PR24565() __attribute__((__malloc__));
 
 // CHECK: class __attribute__((consumable("unknown"))) AttrTester1
 class __attribute__((consumable(unknown))) AttrTester1 {
   // CHECK: void callableWhen() __attribute__((callable_when("unconsumed", "consumed")));
   void callableWhen()  __attribute__((callable_when("unconsumed", "consumed")));
 };
+
+// CHECK: class __single_inheritance SingleInheritance;
+class __single_inheritance SingleInheritance;
+
+// CHECK: class __multiple_inheritance MultipleInheritance;
+class __multiple_inheritance MultipleInheritance;
+
+// CHECK: class __virtual_inheritance VirtualInheritance;
+class __virtual_inheritance VirtualInheritance;