clang/test/Preprocessor/has_attribute_errors.cpp

   1 // RUN: %clang_cc1 -triple i386-unknown-unknown -Eonly -verify %s
   2
   3 // We warn users if they write an attribute like
   4 // [[__clang__::fallthrough]] because __clang__ is a macro that expands to 1.
   5 // Instead, we suggest users use [[_Clang::fallthrough]] in this situation.
   6 // However, because __has_cpp_attribute (and __has_c_attribute) require
   7 // expanding their argument tokens, __clang__ expands to 1 in the feature test
   8 // macro as well. We don't currently give users a kind warning in this case,
   9 // but we previously did not expand macros and so this would return 0. Now that
  10 // we properly expand macros, users will now get an error about using incorrect
  11 // syntax.
  12
  13 __has_cpp_attribute(__clang__::fallthrough) // expected-error {{missing ')' after <numeric_constant>}} \
  14                                             // expected-note {{to match this '('}} \
  15                                             // expected-error {{builtin feature check macro requires a parenthesized identifier}}
  16