alignment flag triggers warning: assuming pointer wraparound does not occur

[uohmak4fvpqe]

I noticed that using the alignment flag as in fmt::print(" ... {:<42} ...", "test") annoyingly triggers -Wstrict-overflow (GCC) :

client.cc:29:5:   in 'constexpr' expansion of 'fmt::v8::basic_format_string<char, const std::basic_string_view<char, std::char_traits<char> >&, const std::basic_string_view<char, std::char_traits<char> >&>("connection to {}{:<12}...\0337")'
/home/linuxbrew/.linuxbrew/include/fmt/core.h:3069:40:   in 'constexpr' expansion of 'fmt::v8::detail::parse_format_string<true, char, fmt::v8::detail::format_string_checker<char, fmt::v8::detail::error_handler, std::basic_string_view<char, std::char_traits<char> >, std::basic_string_view<char, std::char_traits<char> > > >(((fmt::v8::basic_format_string<char, const std::basic_string_view<char, std::char_traits<char> >&, const std::basic_string_view<char, std::char_traits<char> >&>*)this)->fmt::v8::basic_format_string<char, const std::basic_string_view<char, std::char_traits<char> >&, const std::basic_string_view<char, std::char_traits<char> >&>::str_, fmt::v8::detail::format_string_checker<char, fmt::v8::detail::error_handler, std::basic_string_view<char, std::char_traits<char> >, std::basic_string_view<char, std::char_traits<char> > >(fmt::v8::basic_string_view<char>(((const char*)s)), (fmt::v8::detail::error_handler(), fmt::v8::detail::error_handler())))'
/home/linuxbrew/.linuxbrew/include/fmt/core.h:2627:44:   in 'constexpr' expansion of 'fmt::v8::detail::parse_replacement_field<char, fmt::v8::detail::format_string_checker<char, fmt::v8::detail::error_handler, std::basic_string_view<char, std::char_traits<char> >, std::basic_string_view<char, std::char_traits<char> > >&>((p + -1), end, (* & handler))'
/home/linuxbrew/.linuxbrew/include/fmt/core.h:2602:38:   in 'constexpr' expansion of '(& handler)->fmt::v8::detail::format_string_checker<char, fmt::v8::detail::error_handler, std::basic_string_view<char, std::char_traits<char> >, std::basic_string_view<char, std::char_traits<char> > >::on_format_specs(adapter.fmt::v8::detail::parse_replacement_field<char, fmt::v8::detail::format_string_checker<char, fmt::v8::detail::error_handler, std::basic_string_view<char, std::char_traits<char> >, std::basic_string_view<char, std::char_traits<char> > >&>(const char*, const char*, fmt::v8::detail::format_string_checker<char, fmt::v8::detail::error_handler, std::basic_string_view<char, std::char_traits<char> >, std::basic_string_view<char, std::char_traits<char> > >&)::id_adapter::arg_id, (begin + 1), end)'
/home/linuxbrew/.linuxbrew/include/fmt/core.h:2933:51:   in 'constexpr' expansion of '((fmt::v8::detail::format_string_checker<char, fmt::v8::detail::error_handler, std::basic_string_view<char, std::char_traits<char> >, std::basic_string_view<char, std::char_traits<char> > >*)this)->fmt::v8::detail::format_string_checker<char, fmt::v8::detail::error_handler, std::basic_string_view<char, std::char_traits<char> >, std::basic_string_view<char, std::char_traits<char> > >::parse_funcs_[id](((fmt::v8::detail::format_string_checker<char, fmt::v8::detail::error_handler, std::basic_string_view<char, std::char_traits<char> >, std::basic_string_view<char, std::char_traits<char> > >*)this)->fmt::v8::detail::format_string_checker<char, fmt::v8::detail::error_handler, std::basic_string_view<char, std::char_traits<char> >, std::basic_string_view<char, std::char_traits<char> > >::context_)'
/home/linuxbrew/.linuxbrew/include/fmt/core.h:2676:17:   in 'constexpr' expansion of 'f.fmt::v8::formatter<fmt::v8::basic_string_view<char>, char, void>::parse<fmt::v8::detail::compile_parse_context<char, fmt::v8::detail::error_handler> >((* & ctx))'
/home/linuxbrew/.linuxbrew/include/fmt/core.h:2984:41:   in 'constexpr' expansion of 'fmt::v8::detail::parse_format_specs<char, fmt::v8::detail::specs_checker<fmt::v8::detail::dynamic_specs_handler<fmt::v8::detail::compile_parse_context<char, fmt::v8::detail::error_handler> > >&>(begin, end, checker)'
/home/linuxbrew/.linuxbrew/include/fmt/core.h:2515:22:   in 'constexpr' expansion of 'fmt::v8::detail::parse_align<char, fmt::v8::detail::specs_checker<fmt::v8::detail::dynamic_specs_handler<fmt::v8::detail::compile_parse_context<char, fmt::v8::detail::error_handler> > >&>(begin, end, (* & handler))'
../../up/io.hh:111:93: warning: assuming pointer wraparound does not occur when comparing P +- C1 with P +- C2 [-Wstrict-overflow]

[vitaut]

I was not able to repro it on current master: https://godbolt.org/z/YP6Kfoq38.

[uohmak4fvpqe]

I was not able to repro it on current master: https://godbolt.org/z/YP6Kfoq38.

It does with -std=c++20

[vitaut]

Fixed in 8e2e4d4. Thanks for reporting.