// Running the sanitizer coverage pass will add undefined symbols to
  // functions in compiler-rt's "sanitizer_common". "sanitizer_common" isn't
  // shipped as a separate library we can link with. However those are defined
  // in the various sanitizer runtime libraries so we require that we are
  // doing a sanitized build so we pick up the required functions during
  // linking.
  if (opts.CoverageType != llvm::SanitizerCoverageOptions::SCK_None &&
      !sanitizers) {
    Diags.diagnose(SourceLoc(), diag::error_option_requires_sanitizer,
                   A->getSpelling());
    return llvm::SanitizerCoverageOptions();
  }