Ioss: fmt is failing to compile against LLVM 20

[jjellio]

I don't have a good way to reproduce this. I've been evaluating a "to be released" AMD release, which uses LLVM 20 under the hood. It's falling over due to FMT. This will become live with ROCM 6.4. Perhaps if there is a regular LLVM 20 compiler hanging around (I don't have one built within SNL's compute ecosystem).

In file included from /g/g20/jjellio/src/github/Trilinos/packages/seacas/libraries/ioss/src/Ioss_Region.C:40:
In file included from /g/g20/jjellio/src/github/Trilinos/packages/seacas/libraries/ioss/src/private_copy_fmt/fmt/core.h:5:
In file included from /g/g20/jjellio/src/github/Trilinos/packages/seacas/libraries/ioss/src/private_copy_fmt/fmt/format.h:4417:
/g/g20/jjellio/src/github/Trilinos/packages/seacas/libraries/ioss/src/private_copy_fmt/fmt/format-inl.h:60:22: error: call to consteval function 'fmt::basic_format_string<char, const char (&)[7], int &>::basic_format_string<FMT_COMPILE_STRING, 0>' is not a constant expression
   60 |   fmt::format_to(it, FMT_STRING("{}{}"), ERROR_STR, error_code);
      |                      ^
/g/g20/jjellio/src/github/Trilinos/packages/seacas/libraries/ioss/src/private_copy_fmt/fmt/format.h:1827:23: note: expanded from macro 'FMT_STRING'
 1827 | #define FMT_STRING(s) FMT_STRING_IMPL(s, fmt::detail::compile_string, )
      |                       ^
/g/g20/jjellio/src/github/Trilinos/packages/seacas/libraries/ioss/src/private_copy_fmt/fmt/format.h:1806:3: note: expanded from macro 'FMT_STRING_IMPL'
 1806 |   [] {                                                                        \
      |   ^
/g/g20/jjellio/src/github/Trilinos/packages/seacas/libraries/ioss/src/private_copy_fmt/fmt/base.h:780:54: note: subexpression not valid in a constant expression
  780 |     format_str_.remove_prefix(detail::to_unsigned(it - begin()));
      |                                                   ~~~^~~~~~~~~
/g/g20/jjellio/src/github/Trilinos/packages/seacas/libraries/ioss/src/private_copy_fmt/fmt/base.h:2762:5: note: in call to 'this->context_.advance_to(&"{}{}"[1])'
 2762 |     context_.advance_to(begin);
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~
/g/g20/jjellio/src/github/Trilinos/packages/seacas/libraries/ioss/src/private_copy_fmt/fmt/base.h:2757:5: note: in call to 'this->on_format_specs(0, &"{}{}"[1], &"{}{}"[1])'
 2757 |     on_format_specs(id, begin, begin);  // Call parse() on empty specs.
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/g/g20/jjellio/src/github/Trilinos/packages/seacas/libraries/ioss/src/private_copy_fmt/fmt/base.h:2582:5: note: in call to 'handler.on_replacement_field(0, &"{}{}"[1])'
 2582 |     handler.on_replacement_field(handler.on_arg_id(), begin);
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/g/g20/jjellio/src/github/Trilinos/packages/seacas/libraries/ioss/src/private_copy_fmt/fmt/base.h:2614:21: note: in call to 'parse_replacement_field<char, fmt::detail::format_string_checker<char, char[7], int> &>(&"{}{}"[1], &"{}{}"[4], checker(s))'
 2614 |         begin = p = parse_replacement_field(p - 1, end, handler);
      |                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/g/g20/jjellio/src/github/Trilinos/packages/seacas/libraries/ioss/src/private_copy_fmt/fmt/base.h:2885:7: note: in call to 'parse_format_string<true, char, fmt::detail::format_string_checker<char, char[7], int>>({&"{}{}"[0], 4}, checker(s))'
 2885 |       detail::parse_format_string<true>(str_, checker(s));
      |       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/g/g20/jjellio/src/github/Trilinos/packages/seacas/libraries/ioss/src/private_copy_fmt/fmt/format-inl.h:60:22: note: in call to 'basic_format_string<FMT_COMPILE_STRING, 0>([] {
    struct __attribute__((visibility("hidden")))  FMT_COMPILE_STRING : fmt::detail::compile_string {
        using char_type [[maybe_unused]] = fmt::remove_cvref_t<decltype("{}{}"[0])>;
        [[maybe_unused]] constexpr operator fmt::basic_string_view<char_type>() const {
            return fmt::detail_exported::compile_string_to_view<char_type>("{}{}");
        }
    };
    return FMT_COMPILE_STRING();
}())'
   60 |   fmt::format_to(it, FMT_STRING("{}{}"), ERROR_STR, error_code);
      |                      ^~~~~~~~~~~~~~~~~~
/g/g20/jjellio/src/github/Trilinos/packages/seacas/libraries/ioss/src/private_copy_fmt/fmt/format.h:1827:23: note: expanded from macro 'FMT_STRING'
 1827 | #define FMT_STRING(s) FMT_STRING_IMPL(s, fmt::detail::compile_string, )
      |                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/g/g20/jjellio/src/github/Trilinos/packages/seacas/libraries/ioss/src/private_copy_fmt/fmt/format.h:1806:3: note: expanded from macro 'FMT_STRING_IMPL'
 1806 |   [] {                                                                        \
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 1807 |     /* Use the hidden visibility as a workaround for a GCC bug (#1973). */    \
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 1808 |     /* Use a macro-like name to avoid shadowing warnings. */                  \
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 1809 |     struct FMT_VISIBILITY("hidden") FMT_COMPILE_STRING : base {               \
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 1810 |       using char_type FMT_MAYBE_UNUSED = fmt::remove_cvref_t<decltype(s[0])>; \
      |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 1811 |       FMT_MAYBE_UNUSED FMT_CONSTEXPR explicit                                 \
      |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 1812 |       operator fmt::basic_string_view<char_type>() const {                    \
      |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 1813 |         return fmt::detail_exported::compile_string_to_view<char_type>(s);    \
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 1814 |       }                                                                       \
      |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 1815 |     };                                                                        \
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 1816 |     return FMT_COMPILE_STRING();                                              \
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 1817 |   }()
      |   ~~~

[gsjaardema]

Do you know what version of the embedded fmt library is in the Trilinos version you are using. Should be in packages/seacas/libraries/ioss/src/private_copy_fmt/include/fmt/base.h

[jjellio]

I'm getting this via Trilinos/develop, my path has base at fmt/base.h

[jjellio@elcap1008:Trilinos]$ git log packages/seacas/libraries/ioss/src/private_copy_fmt/fmt/base.h
commit be2bce43a32ede3981f660397dbe9a2a68349a78
Author: Greg Sjaardema <gdsjaar@sandia.gov>
Date:   Tue Aug 27 18:07:56 2024 -0600

    Specify HEADER_ONLY use of fmt

Seems inline with
https://github.com/trilinos/Trilinos/blob/master/packages/seacas/libraries/ioss/src/private_copy_fmt/fmt/base.h

[jjellio]

I could look at building an LLVM 20 build, and eliminating AMD's stuff. Given this isn't device code, I doubt their stuff is making a difference though.

[gsjaardema]

We are using a very up-to-date copy of libfmt, 11.0.2 and the current is 11.1.2

I don't see any recent changes that were added to deal with llvm 20, but will try using lib::fmt on compiler explorer and see if I can reproduce what you are seeing...

[jjellio]

I talked with AMD today - the next release from them will be LLVM 19. This beta I have is a bit forward looking, so maybe we can table this. It did fall over with LLVM 20, but maybe it will work with 19.

[gsjaardema]

I'm planning to take a look at fmt usage with llvm 20 on compiler explorer, but havent had a chance yet...