Make sure special wchar_t support is enabled

[dmik]

IIRC this is disabled by configure now because kLIBC doesn't implement all necessary wide character functions (so the respective configure test fails).

When enabled, gcc defines _GLIBCXX_USE_WCHAR_T which enables special code for wide characters. This code includes e.g. a std::is_integral<wchar_t> specialization returning true instead of false and a lot of other things.

The problem was found while working on the QTypeInfo<wchar_t> specialization for Qt 5 within https://github.com/bitwiseworks/qtbase-os2/issues/29.

Note that we may force such support with --enable-wchar_t but a test build needs to be done to check if it will work with our kLIBC.

[dmik]

The configure test is this one:

              #include <wchar.h>
              #include <stddef.h>
              wint_t i;
              long l = WEOF;
              long j = WCHAR_MIN;
              long k = WCHAR_MAX;
              namespace test
              {
            using ::btowc;
            using ::fgetwc;
            using ::fgetws;
            using ::fputwc;
            using ::fputws;
            using ::fwide;
            using ::fwprintf;
            using ::fwscanf;
            using ::getwc;
            using ::getwchar;
            using ::mbrlen;
            using ::mbrtowc;
            using ::mbsinit;
            using ::mbsrtowcs;
            using ::putwc;
            using ::putwchar;
            using ::swprintf;
            using ::swscanf;
            using ::ungetwc;
            using ::vfwprintf;
            using ::vswprintf;
            using ::vwprintf;
            using ::wcrtomb;
            using ::wcscat;
            using ::wcschr;
            using ::wcscmp;
            using ::wcscoll;
            using ::wcscpy;
            using ::wcscspn;
            using ::wcsftime;
            using ::wcslen;
            using ::wcsncat;
            using ::wcsncmp;
            using ::wcsncpy;
            using ::wcspbrk;
            using ::wcsrchr;
            using ::wcsrtombs;
            using ::wcsspn;
            using ::wcsstr;
            using ::wcstod;
            using ::wcstok;
            using ::wcstol;
            using ::wcstoul;
            using ::wcsxfrm;
            using ::wctob;
            using ::wmemchr;
            using ::wmemcmp;
            using ::wmemcpy;
            using ::wmemmove;
            using ::wmemset;
            using ::wprintf;
            using ::wscanf;
              }

Currently, its compilation fails with this:

t.cpp:10:12: error: '::fgetwc' has not been declared
    using ::fgetwc;
            ^
t.cpp:11:12: error: '::fgetws' has not been declared
    using ::fgetws;
            ^
t.cpp:12:12: error: '::fputwc' has not been declared
    using ::fputwc;
            ^
t.cpp:13:12: error: '::fputws' has not been declared
    using ::fputws;
            ^
t.cpp:15:12: error: '::fwprintf' has not been declared
    using ::fwprintf;
            ^
t.cpp:16:12: error: '::fwscanf' has not been declared
    using ::fwscanf;
            ^
t.cpp:17:12: error: '::getwc' has not been declared
    using ::getwc;
            ^
t.cpp:18:12: error: '::getwchar' has not been declared
    using ::getwchar;
            ^
t.cpp:23:12: error: '::putwc' has not been declared
    using ::putwc;
            ^
t.cpp:24:12: error: '::putwchar' has not been declared
    using ::putwchar;
            ^
t.cpp:25:12: error: '::swprintf' has not been declared
    using ::swprintf;
            ^
t.cpp:26:12: error: '::swscanf' has not been declared
    using ::swscanf;
            ^
t.cpp:27:12: error: '::ungetwc' has not been declared
    using ::ungetwc;
            ^
t.cpp:28:12: error: '::vfwprintf' has not been declared
    using ::vfwprintf;
            ^
t.cpp:29:12: error: '::vswprintf' has not been declared
    using ::vswprintf;
            ^
t.cpp:30:12: error: '::vwprintf' has not been declared
    using ::vwprintf;
            ^
t.cpp:59:12: error: '::wprintf' has not been declared
    using ::wprintf;
            ^
t.cpp:60:12: error: '::wscanf' has not been declared
    using ::wscanf;
            ^

So we miss quite a bit.

[dmik]

Note also that kLIBC has other issues with wchar_t, e.g. WCHAR_MIN and WCHAR_MAX which are currently defined as INT_MIN and INT_MAX. This is seriously wrong because wchar_t is 2 bytes (not 4 bytes) under OS/2. There is a kLIBC ticket for this: http://trac.netlabs.org/libc/ticket/332. And I also created our own LIBC ticket for this where it's going to be fixed one day: https://github.com/bitwiseworks/libc/issues/8.

[dmik]

The relevant commit with workarounds that need to be undone once this is fixed is this one: https://github.com/bitwiseworks/qtdeclarative-os2/commit/e7a97582cd3174aaa5c8533df37fe86efdc5f740

[dmik]

This is closed in favor of https://github.com/bitwiseworks/gcc-os2/issues/16.