undefined symbol: char fmt::v7::detail::thousands_sep_impl<char>(fmt::v7::detail::locale_ref)

[NobodyXu]

I am using fmt-7.1.3 in my own project swaystatus, however after I define FMT_STATIC_THOUSANDS_SEPARATOR to ',',
ld.lld with lto enabled failed:

ld.lld: error: undefined symbol: char fmt::v7::detail::thousands_sep_impl<char>(fmt::v7::detail::loca
le_ref)
>>> referenced by ld-temp.o
>>>               lto.tmp:(void fmt::v7::detail::handle_int_type_spec<fmt::v7::detail::int_writer<fmt
::v7::detail::buffer_appender<char>, char, unsigned long>&>(char, fmt::v7::detail::int_writer<fmt::v7
::detail::buffer_appender<char>, char, unsigned long>&))
clang-11: error: linker command failed with exit code 1 (use -v to see invocation)

I've tried define FMT_STATIC_THOUSANDS_SEPARATOR to ',' in every file, but it doesn't solve my problem.

[vitaut]

Fixed one related issue in e8eff3b but note that you have to compile {fmt} with FMT_STATIC_THOUSANDS_SEPARATOR too, not just your code.

[NobodyXu]

@vitaut Thank you.

I uses this library in FMT_HEADER_ONLYmode, so it should be fine to only define FMT_STATIC_THOUSANDS_SEPARATOR in the files include fmt, right?

[NobodyXu]

@vitaut Unfortunately, e8eff3b doesn't work for me.

I am having more errors:

ld.lld: error: undefined symbol: fmt::v7::format_error::~format_error()
>>> referenced by ld-temp.o
>>>               lto.tmp:(fmt::v7::detail::specs_setter<char>::on_fill(fmt::v7::basic_string_view<cha
r>))
>>> referenced by ld-temp.o
>>>               lto.tmp:(fmt::v7::formatter<swaystatus::mem_size_t, char, void>::parse(fmt::v7::basi
c_format_parse_context<char, fmt::v7::detail::error_handler>&))
>>> referenced by ld-temp.o
>>>               lto.tmp:(fmt::v7::formatter<swaystatus::mem_size_t, char, void>::parse(fmt::v7::basi
c_format_parse_context<char, fmt::v7::detail::error_handler>&))
>>> referenced 5 more times

ld.lld: error: undefined symbol: char fmt::v7::detail::thousands_sep_impl<char>(fmt::v7::detail::local
e_ref)
>>> referenced by ld-temp.o
>>>               lto.tmp:(void fmt::v7::detail::handle_int_type_spec<fmt::v7::detail::int_writer<fmt:
:v7::detail::buffer_appender<char>, char, unsigned long>&>(char, fmt::v7::detail::int_writer<fmt::v7::
detail::buffer_appender<char>, char, unsigned long>&))
clang-11: error: linker command failed with exit code 1 (use -v to see invocation)

and I was also forced to work around formatter not found error by wrapping NMIPConfig* in a class and specialize fmt::format for the wrapper instead of the NMIPConfig*.

[NobodyXu]

@vitaut I have found a solution to it:

I have to #define FMT_HEADER_ONLY in every translation unit that #includes <fmt/format.h>, not just the printer.cc.

But then, the compiled binary seems to be 3K larger.

[vitaut]

it should be fine to only define FMT_STATIC_THOUSANDS_SEPARATOR in the files include fmt, right?

Yes but as you already found out it should be consistently defined everywhere.

[NobodyXu]

Thank you very much for taking your time to solve my problem.

Everything works fine right now and I’ve able to striped away 21K from the executable built.