thurston suggestion

Created using spr 1.3.4

Author: fmayer

clang/include/clang/Basic/Features.def

@@ -54,6 +54,7 @@ FEATURE(memtag_globals,
 FEATURE(xray_instrument, LangOpts.XRayInstrument)
 FEATURE(undefined_behavior_sanitizer,
         LangOpts.Sanitize.hasOneOf(SanitizerKind::Undefined))
+FEATURE(undefined_behavior_sanitizer_finegrained_feature_checks, true)
 // These are all part of undefined_behavior_sanitizer:
 FEATURE(alignment_sanitizer,
         LangOpts.Sanitize.has(SanitizerKind::Alignment))

clang/test/Lexer/has_feature_undefined_behavior_sanitizer.cpp

@@ -23,6 +23,10 @@
 
 // RUN: %clang -E  %s -o - | FileCheck --check-prefix=CHECK-NO-UBSAN %s
 
+#if !__has_feature(undefined_behavior_sanitizer_finegrained_feature_checks)
+#error "Missing undefined_behavior_sanitizer_finegrained_feature_checks"
+#endif
+
 #if __has_feature(undefined_behavior_sanitizer)
 int UBSanEnabled();
 #else