[Clang][Sema] Fix crash in CheckUsingDeclQualifier due to diagnostic missing an argument (#161277)

Crash report came in and it was pretty obvious the diagnostic line was
just missing an argument. I supplied the argument and added a test.

Fixes: #161072

Author: shafik

clang/lib/Sema/SemaDeclCXX.cpp

@@ -13660,7 +13660,7 @@ bool Sema::CheckUsingDeclQualifier(SourceLocation UsingLoc, bool HasTypename,
 
     if (Cxx20Enumerator) {
       Diag(NameLoc, diag::warn_cxx17_compat_using_decl_non_member_enumerator)
-          << SS.getRange();
+          << SS.getScopeRep() << SS.getRange();
       return false;
     }
 

clang/test/SemaCXX/cxx98-compat.cpp

@@ -1,6 +1,7 @@
-// RUN: %clang_cc1 -fsyntax-only -std=c++11 -Wc++98-compat -verify %s
-// RUN: %clang_cc1 -fsyntax-only -std=c++14 -Wc++98-compat -verify %s -DCXX14COMPAT
-// RUN: %clang_cc1 -fsyntax-only -std=c++17 -Wc++98-compat -verify %s -DCXX14COMPAT -DCXX17COMPAT
+// RUN: %clang_cc1 -fsyntax-only -std=c++11 -Wc++98-compat -verify=expected,not-cpp20 %s
+// RUN: %clang_cc1 -fsyntax-only -std=c++14 -Wc++98-compat -verify=expected,not-cpp20 %s -DCXX14COMPAT
+// RUN: %clang_cc1 -fsyntax-only -std=c++17 -Wc++98-compat -verify=expected,not-cpp20 %s -DCXX14COMPAT -DCXX17COMPAT
+// RUN: %clang_cc1 -fsyntax-only -std=c++20 -Wc++98-compat -verify=expected,cpp20 %s -DCXX14COMPAT -DCXX17COMPAT
 
 namespace std {
   struct type_info;
@@ -226,7 +227,8 @@ void TrivialButNonPODThroughEllipsis() {
 }
 
 struct HasExplicitConversion {
-  explicit operator bool(); // expected-warning {{explicit conversion functions are incompatible with C++98}}
+  // FIXME I think we should generate this diagnostic in C++20
+  explicit operator bool(); // not-cpp20-warning {{explicit conversion functions are incompatible with C++98}}
 };
 
 struct Struct {};
@@ -430,3 +432,12 @@ void ctad_test() {
   CTAD t = s; // expected-warning {{class template argument deduction is incompatible with C++ standards before C++17}}
 }
 #endif
+
+namespace GH161702 {
+struct S {
+  enum E { A };
+  using E::A; // expected-warning {{enumeration type in nested name specifier is incompatible with C++98}}
+              // not-cpp20-error@-1 {{using declaration refers to its own class}}
+             // cpp20-warning@-2 {{member using declaration naming non-class ''E'' enumerator is incompatible with C++ standards before C++20}}
+};
+}