[PATCH v3 2/4] include: only define _tcs macros on suitable libc.

[Puetz Kevin A]

> -----Original Message-----
> From: Jacek Caban <jacek at codeweavers.com>
> Sent: Wednesday, September 30, 2020 4:08 PM
> 
> Hi Kevin,
> 
> On 24/09/2020 17:12, Kevin Puetz wrote:
> > --- a/include/tchar.h
> > +++ b/include/tchar.h
> > @@ -37,9 +37,15 @@ extern "C" {
> >   #define _strninc(str,n)         (((char*)(str))+(n))
> >   #define _strspnp(s1,s2)         (*((s1)+=strspn((s1),(s2))) ? (s1) : NULL)
> >
> > +#if defined(__MSVCRT__) || defined(_MSC_VER) ||
> (defined(WINE_UNICODE_NATIVE) && defined(_UNICODE)) ||
> !(defined(_UNICODE) || defined(_MBCS))
> >
> 
> 
> This seems to be more complicated than it needs to be. Since guarded
> macros really belong to crt, maybe we should have a guard bellow
> includes of string.h, wchar.h, etc. (to give corecrt.h a chance to be
> included) and simply use:
> 
> #ifdef __WINE_USE_MSVCRT

I guess I was (again) aiming for as much portability as I could.

Wine 5.0.x allowed the use of tchar.h for 2 cases:
1. __MSVCRT__ (i.e. -mno-cygwin)
2. "plain" 8-bit text (no _UNICODE or _MBCS)

Anything else got a #error. But any settings allowed to
#include <tchar.h> at all got the _tcs* functions.

My original patches (which c1208903 applied partially)
removed that #error to allow using tchar.h with char16_t.
They kept the _tcs macros guarded since a standard libc
won't have utf16 functions, but allowed a couple more cases:

3. _UNICODE && WINE_UNICODE_NATIVE (i.e. -fshort-wchar)
   This was just by analogy: if char str functions were OK for 8-bit _TCHAR,
   the wchar_t wcs functions should be equally OK when _TCHAR==wchar_t 
4. MSVC

I don't really have a specific use for these; I was really submitting this
 clean-up just because I felt c1208903 had left things inconsistent
(_tcs macros defined that won't work, or maybe even compile).
Since that started with (part of) my patch I felt responsible to fix it 😊.

I don't have any objection to simplifying this further, and just ruling that 
_tcs* functions are MSVCRT-only. But I didn't propose that because it
would be remove some functionality that 5.0.x had.

If you want to go that way, though (make a breaking change from 5.0.x),
I think it would make more sense to follow-through all the way and match
the Windows SDK/ucrt split, i.e. move tchar.h into include/msvcrt,
and leave it with no #ifdef.

TCHAR and TEXT() are already in winnt.h, so it seems defensible to 
give glibc just those, keeping _TCHAR, _TEXT, and _tcs*() 
functions for MSVCRT (where they always have usable definitions).

That would break a few things we're compiling with wineg++,
but not in ways that would be hard to fix.