[PATCH] D131307: [Clang] Allow downgrading to a warning the diagnostic for setting a non fixed enum to a value outside the range of the enumeration values

[Stephan Bergmann via Phabricator via cfe-commits]

sberg added a comment.

With this commit,

  $ cat test.cc
  #include "boost/numeric/conversion/cast.hpp"
  int main() { return boost::numeric_cast<int>(0L); }
  
  $ clang++ test.cc

succeeds without any diagnostic, while with its parent commit https://github.com/llvm/llvm-project/commit/b3645353041818f61e2580635409ddb81ff5a272 " [Clang] Diagnose ill-formed constant expression when setting a non fixed enum to a value outside the range of the enumeration values" it had started to fail with

  In file included from test.cc:1:
  In file included from /usr/include/boost/numeric/conversion/cast.hpp:33:
  In file included from /usr/include/boost/numeric/conversion/converter.hpp:13:
  In file included from /usr/include/boost/numeric/conversion/conversion_traits.hpp:13:
  In file included from /usr/include/boost/numeric/conversion/detail/conversion_traits.hpp:18:
  In file included from /usr/include/boost/numeric/conversion/detail/int_float_mixture.hpp:19:
  In file included from /usr/include/boost/mpl/integral_c.hpp:32:
  /usr/include/boost/mpl/aux_/integral_wrapper.hpp:73:31: error: non-type template argument is not a constant expression
      typedef AUX_WRAPPER_INST( BOOST_MPL_AUX_STATIC_CAST(AUX_WRAPPER_VALUE_TYPE, (value - 1)) ) prior;
              ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  /usr/include/boost/mpl/aux_/static_cast.hpp:24:47: note: expanded from macro 'BOOST_MPL_AUX_STATIC_CAST'
  #   define BOOST_MPL_AUX_STATIC_CAST(T, expr) static_cast<T>(expr)
                                                ^
  /usr/include/boost/mpl/integral_c.hpp:31:54: note: expanded from macro 'AUX_WRAPPER_INST'
  #define AUX_WRAPPER_INST(value) AUX_WRAPPER_NAME< T, value >
                                                       ^~~~~
  /usr/include/boost/numeric/conversion/detail/meta.hpp:30:46: note: in instantiation of template class 'mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, boost::numeric::builtin_to_builtin>' requested here
         enum { x = ( BOOST_MPL_AUX_VALUE_WKND(T1)::value == BOOST_MPL_AUX_VALUE_WKND(T2)::value ) };
                                               ^
  /usr/include/boost/mpl/if.hpp:63:68: note: in instantiation of template class 'boost::numeric::convdetail::equal_to<mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, boost::numeric::builtin_to_builtin>, mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, boost::numeric::builtin_to_builtin>>' requested here
            BOOST_MPL_AUX_STATIC_CAST(bool, BOOST_MPL_AUX_VALUE_WKND(T1)::value)
                                                                     ^
  /usr/include/boost/mpl/eval_if.hpp:37:22: note: in instantiation of template class 'boost::mpl::if_<boost::numeric::convdetail::equal_to<mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, boost::numeric::builtin_to_builtin>, mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, boost::numeric::builtin_to_builtin>>, boost::mpl::identity<boost::numeric::convdetail::get_subranged_BuiltIn2BuiltIn<int, long>>, boost::mpl::eval_if<boost::numeric::convdetail::equal_to<mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, boost::numeric::builtin_to_builtin>, mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, boost::numeric::builtin_to_udt>>, boost::mpl::identity<boost::mpl::identity<boost::numeric::convdetail::subranged_BuiltIn2Udt<int, long>>>, boost::mpl::if_<boost::numeric::convdetail::equal_to<mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, boost::numeric::builtin_to_builtin>, mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, boost::numeric::udt_to_builtin>>, boost::mpl::identity<boost::numeric::convdetail::subranged_Udt2BuiltIn<int, long>>, boost::mpl::identity<boost::numeric::convdetail::subranged_Udt2Udt<int, long>>>>>' requested here
      typedef typename if_<C,F1,F2>::type f_;
                       ^
  /usr/include/boost/numeric/conversion/detail/meta.hpp:81:12: note: in instantiation of template class 'boost::mpl::eval_if<boost::numeric::convdetail::equal_to<mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, boost::numeric::builtin_to_builtin>, mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, boost::numeric::builtin_to_builtin>>, boost::mpl::identity<boost::numeric::convdetail::get_subranged_BuiltIn2BuiltIn<int, long>>, boost::mpl::eval_if<boost::numeric::convdetail::equal_to<mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, boost::numeric::builtin_to_builtin>, mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, boost::numeric::builtin_to_udt>>, boost::mpl::identity<boost::mpl::identity<boost::numeric::convdetail::subranged_BuiltIn2Udt<int, long>>>, boost::mpl::if_<boost::numeric::convdetail::equal_to<mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, boost::numeric::builtin_to_builtin>, mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, boost::numeric::udt_to_builtin>>, boost::mpl::identity<boost::numeric::convdetail::subranged_Udt2BuiltIn<int, long>>, boost::mpl::identity<boost::numeric::convdetail::subranged_Udt2Udt<int, long>>>>>' requested here
        mpl::eval_if<is_case0,Case0TypeQ,choose_1_2_3Q>::type
             ^
  /usr/include/boost/numeric/conversion/detail/udt_builtin_mixture.hpp:41:7: note: in instantiation of template class 'boost::numeric::convdetail::ct_switch4<mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, boost::numeric::builtin_to_builtin>, mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, boost::numeric::builtin_to_builtin>, mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, boost::numeric::builtin_to_udt>, mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, boost::numeric::udt_to_builtin>, boost::numeric::convdetail::get_subranged_BuiltIn2BuiltIn<int, long>, boost::mpl::identity<boost::numeric::convdetail::subranged_BuiltIn2Udt<int, long>>, boost::mpl::identity<boost::numeric::convdetail::subranged_Udt2BuiltIn<int, long>>, boost::mpl::identity<boost::numeric::convdetail::subranged_Udt2Udt<int, long>>>' requested here
        ct_switch4<UdtMixture
        ^
  /usr/include/boost/numeric/conversion/detail/is_subranged.hpp:205:9: note: (skipping 3 contexts in backtrace; use -ftemplate-backtrace-limit=0 to see all)
          for_udt_builtin_mixture<udt_builtin_mixture, BuiltIn2BuiltInQ, BuiltIn2UdtQ, Udt2BuiltInQ, Udt2UdtQ>::type
          ^
  /usr/include/boost/numeric/conversion/conversion_traits.hpp:22:7: note: in instantiation of template class 'boost::numeric::convdetail::non_trivial_traits_impl<int, long>' requested here
      : convdetail::get_conversion_traits<T,S>::type
        ^
  /usr/include/boost/numeric/conversion/detail/converter.hpp:584:22: note: in instantiation of template class 'boost::numeric::conversion_traits<int, long>' requested here
      typedef typename Traits::trivial trivial ;
                       ^
  /usr/include/boost/numeric/conversion/converter.hpp:29:32: note: in instantiation of template class 'boost::numeric::convdetail::get_converter_impl<boost::numeric::conversion_traits<int, long>, boost::numeric::def_overflow_handler, boost::numeric::Trunc<long>, boost::numeric::raw_converter<boost::numeric::conversion_traits<int, long>>, boost::numeric::UseInternalRangeChecker>' requested here
  struct converter : convdetail::get_converter_impl<Traits,
                                 ^
  /usr/include/boost/numeric/conversion/cast.hpp:53:16: note: in instantiation of template class 'boost::numeric::converter<int, long, boost::numeric::conversion_traits<int, long>, boost::numeric::def_overflow_handler, boost::numeric::Trunc<long>>' requested here
          return converter::convert(arg);
                 ^
  test.cc:2:28: note: in instantiation of function template specialization 'boost::numeric_cast<int, long>' requested here
  int main() { return boost::numeric_cast<int>(0L); }
                             ^
  /usr/include/boost/mpl/aux_/integral_wrapper.hpp:73:31: note: integer value -1 is outside the valid range of values [0, 3] for this enumeration type
      typedef AUX_WRAPPER_INST( BOOST_MPL_AUX_STATIC_CAST(AUX_WRAPPER_VALUE_TYPE, (value - 1)) ) prior;
                                ^
  /usr/include/boost/mpl/aux_/static_cast.hpp:24:47: note: expanded from macro 'BOOST_MPL_AUX_STATIC_CAST'
  #   define BOOST_MPL_AUX_STATIC_CAST(T, expr) static_cast<T>(expr)
                                                ^

I'm not sure that's an intended change?  (And sorry for not stripping down the reproducer to something self-contained.)


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D131307/new/

https://reviews.llvm.org/D131307