Kicad @7.0.11: fails to build with clang-19 and libc++ 19, after upgrade to macos 15

[mpbb77 (Miguel Branco)]

Building Kicad will fail while building thirdparty/nanodbc due to deprecation of std::char_traits<> for types other than char, char8_t, char16_t, char32_t and wchar_t, with errors like:

.../thirdparty/nanodbc/nanodbc/nanodbc.cpp:261:25: error: implicit instantiation of undefined template 'std::char_traits<unsigned short>'

261 | auto const n = std::char_traits<NANODBC_SQLCHAR>::length(array);

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/usr/include/c++/v1/string/char_traits.h:45:8: note: template is declared here

45 | struct char_traits;

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.../thirdparty/nanodbc/nanodbc/nanodbc.cpp:3576:52: error: implicit instantiation of undefined template 'std::char_traits<unsigned short>'

3576 | dsn.name = string(&name[0], &name[std::char_traits<NANODBC_SQLCHAR>::length(name)]);

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/usr/include/c++/v1/string/char_traits.h:45:8: note: template is declared here

45 | struct char_traits;

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.../thirdparty/nanodbc/nanodbc/nanodbc.cpp:3578:49: error: implicit instantiation of undefined template 'std::char_traits<unsigned short>'

3578 | string(&driver[0], &driver[std::char_traits<NANODBC_SQLCHAR>::length(driver)]);

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/usr/include/c++/v1/string/char_traits.h:45:8: note: template is declared here

45 | struct char_traits;

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.../thirdparty/nanodbc/nanodbc/nanodbc.cpp:3629:54: error: implicit instantiation of undefined template 'std::char_traits<unsigned short>'

3629 | drv.name = string(&descr[0], &descr[std::char_traits<NANODBC_SQLCHAR>::length(descr)]);

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/usr/include/c++/v1/string/char_traits.h:45:8: note: template is declared here

45 | struct char_traits;

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and

/usr/include/c++/v1/string:820:42: error: implicit instantiation of undefined template 'std::char_traits<unsigned short>'

820 | static_assert(is_same<_CharT, typename traits_type::char_type>::value,

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.../thirdparty/compoundfilereader/compoundfilereader.h:226:21: note: in instantiation of template class 'std::basic_string<unsigned short>' requested here

226 | utf16string dir;

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/usr/include/c++/v1/fwd/string.h:23:29: note: template is declared here

23 | struct _LIBCPP_TEMPLATE_VIS char_traits;

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The same failure can be found on the freebsd bugzilla @ ​https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=281886 and their fix also applies to Macports, as I've applied their patches and the build resumed with no further issues.

[mpbb77 (Miguel Branco)]

Patches from FreeBsd Bugzilla readily applicable to this port