RWC workaround: Use __builtin_trap for ancient Clang (#5458)

Author: StephanTLavavej

stl/inc/type_traits

@@ -335,7 +335,7 @@ constexpr bool is_enum_v = __is_enum(_Ty);
 
 #if _HAS_CXX23
 #if defined(__clang__) && !defined(__EDG__) \
-    && __clang_major__ >= 16 // TRANSITION, DevCom-10870354, Real World Code relying on ancient Clang
+    && __clang_major__ >= 16 // TRANSITION, DevCom-10870354 (MSVC, EDG), VSO-2397560 (RWC relying on ancient Clang)
 _EXPORT_STD template <class _Ty>
 constexpr bool is_scoped_enum_v = __is_scoped_enum(_Ty);
 

stl/inc/yvals.h

@@ -245,6 +245,8 @@ _EMIT_STL_ERROR(STL1008, "_STL_CALL_ABORT_INSTEAD_OF_INVALID_PARAMETER has been
 #ifndef _MSVC_STL_DOOM_FUNCTION
 #ifdef _MSVC_STL_USE_ABORT_AS_DOOM_FUNCTION // The user wants to use abort():
 #define _MSVC_STL_DOOM_FUNCTION(mesg) _CSTD abort()
+#elif defined(__clang__) && __clang_major__ < 19 // TRANSITION, VSO-2397560, Real World Code relying on ancient Clang
+#define _MSVC_STL_DOOM_FUNCTION(mesg) __builtin_trap()
 #elif defined(__clang__) // Use the Clang intrinsic:
 #define _MSVC_STL_DOOM_FUNCTION(mesg) __builtin_verbose_trap("MSVC STL error", mesg)
 #elif defined(_M_CEE) // TRANSITION, VSO-2457624 (/clr silent bad codegen for __fastfail); /clr:pure lacks __fastfail