error: implicit instantiation of undefined template 'std::char_traits<unsigned int>'

[daeho-ro]

Hello,

When this package is build with Xcode 16.3, it gets an error

  /Library/Developer/CommandLineTools/SDKs/MacOSX15.sdk/usr/include/c++/v1/string_view:300:42: error: implicit instantiation of undefined template 'std::char_traits<unsigned int>'
    300 |   static_assert(is_same<_CharT, typename traits_type::char_type>::value,
        |                                          ^
  ../dlib/dlib/matrix/../unicode/unicode.h:508:16: note: in instantiation of template class 'std::basic_string_view<unsigned int>' requested here
    508 |         return temp;
        |                ^
  ../dlib/dlib/matrix/../unicode/unicode.h:508:16: note: while substituting deduced template arguments into function template 'basic_string' [with $0 = (no value)]
  /Library/Developer/CommandLineTools/SDKs/MacOSX15.sdk/usr/include/c++/v1/__fwd/string.h:23:29: note: template is declared here
     23 | struct _LIBCPP_TEMPLATE_VIS char_traits;
        |                             ^
  ../dlib/dlib/unicode/unicode.h../dlib/dlib/unicode/unicode.h::490490::2626::  note: note: in instantiation of template class 'std::basic_string<unsigned int>' requested herein instantiation of template class 'std::basic_string<unsigned int>' requested here
  
  ../dlib/dlib/matrix/../unicode/unicode.h:490:  490 |  26: note: in instantiation of template class 'std::basic_string<unsigned int>' requested here
    490 |   490 |     inline const ustring    inline co convert_utf8_to_utf32 (
        |                          ^
  /Library/Developer/CommandLineTools/SDKs/MacOSX15.sdk/usr/include/c++/v1/__fwd/string.h:23:29: note: template is declared here
     23 | stru   nst ustrininline ccot _LIBCPP_TEMPLATE_VIS char_traits;
        |                             ^
  g convert_utf8_to_utf32 (
        |                          ^
  nst ustring convert_utf8_to_utf32 (
        |                          ^
  /Library/Developer/CommandLineTools/SDKs/MacOSX15.sdk/usr/include/c++/v1/__fwd/string.h:23:29: note: template is declared here
     23 | struct _LIB/Library/Developer/CommandLineTools/SDKs/MacOSX15.sdk/usr/include/c++/v1/__fwd/string.hC:P23P:_29T:E Mnote: Ptemplate is declared hereL
  ATE_   23 | struct _LIBCPP_TEMPLATE_VIS char_traits;
        |                             ^
  VIS char_traits;
        |                             ^

and fine with Xcode 16.4 or others. It seems that the LLVM removed std::char_traits's base template and rollback, but eventually planed to remove again, so this need to be fixed.

• mitie: migrate to python@3.14 Homebrew/homebrew-core#249194
• llvm/llvm-project@c366877

Can you check?
Thanks,

[davisking]

Huh, can you send a PR that works around whatever the issue is?

…

On Wed, Nov 5, 2025 at 6:16 AM Daeho Ro ***@***.***> wrote: *daeho-ro* created an issue (mit-nlp/MITIE#225) <#225> Hello, When this package is build with Xcode 16.3, it gets an error /Library/Developer/CommandLineTools/SDKs/MacOSX15.sdk/usr/include/c++/v1/string_view:300:42: error: implicit instantiation of undefined template 'std::char_traits<unsigned int>' 300 | static_assert(is_same<_CharT, typename traits_type::char_type>::value, | ^ ../dlib/dlib/matrix/../unicode/unicode.h:508:16: note: in instantiation of template class 'std::basic_string_view<unsigned int>' requested here 508 | return temp; | ^ ../dlib/dlib/matrix/../unicode/unicode.h:508:16: note: while substituting deduced template arguments into function template 'basic_string' [with $0 = (no value)] /Library/Developer/CommandLineTools/SDKs/MacOSX15.sdk/usr/include/c++/v1/__fwd/string.h:23:29: note: template is declared here 23 | struct _LIBCPP_TEMPLATE_VIS char_traits; | ^ ../dlib/dlib/unicode/unicode.h../dlib/dlib/unicode/unicode.h::490490::2626:: note: note: in instantiation of template class 'std::basic_string<unsigned int>' requested herein instantiation of template class 'std::basic_string<unsigned int>' requested here ../dlib/dlib/matrix/../unicode/unicode.h:490: 490 | 26: note: in instantiation of template class 'std::basic_string<unsigned int>' requested here 490 | 490 | inline const ustring inline co convert_utf8_to_utf32 ( | ^ /Library/Developer/CommandLineTools/SDKs/MacOSX15.sdk/usr/include/c++/v1/__fwd/string.h:23:29: note: template is declared here 23 | stru nst ustrininline ccot _LIBCPP_TEMPLATE_VIS char_traits; | ^ g convert_utf8_to_utf32 ( | ^ nst ustring convert_utf8_to_utf32 ( | ^ /Library/Developer/CommandLineTools/SDKs/MacOSX15.sdk/usr/include/c++/v1/__fwd/string.h:23:29: note: template is declared here 23 | struct _LIB/Library/Developer/CommandLineTools/SDKs/MacOSX15.sdk/usr/include/c++/v1/__fwd/string.hC:P23P:_29T:E Mnote: Ptemplate is declared hereL ATE_ 23 | struct _LIBCPP_TEMPLATE_VIS char_traits; | ^ VIS char_traits; | ^ and fine with Xcode 16.4 or others. It seems that the LLVM removed std::char_traits's base template and rollback, but eventually planed to remove again, so this need to be fixed. - Homebrew/homebrew-core#249194 <Homebrew/homebrew-core#249194> - ***@***.*** <llvm/llvm-project@c366877> Can you check? Thanks, — Reply to this email directly, view it on GitHub <#225>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABPYFRYOOIRJRSRSLEQWCHL33HMBJAVCNFSM6AAAAACLGOJEWSVHI2DSMVQWIX3LMV43ASLTON2WKOZTGU4TANJRG43TKMI> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>