Hi Kees,
> Basically, the mingw headers are patched for inclusion of the
corresponding
> *x.h files; see also the 'installation and usage' section on
> http://gnuwin32.sourceforge.net/packages/libgw32c.htm. ...
I *really* don't like to do this. IMHO, the headers supplied with the
compiler should be patched *only* to correct defects or omissions, and
then
only with the sanction of the maintainers of the compiler package itself.
If these headers are arbitrarily modified, to accommodate some specific
local build system configuration, then maintenance becomes much more
difficult, when officially sanctioned patches are applied, or when a
compiler upgrade is installed.
> ... Then linking with
> libgw32c.a is usually suffcient to create succesfully an executable.
There
> was some discussion about this on the gnuwin32-users list. The whole
setup
> seemed simple to me, but most users find it difficult to reproduce. It
is on
> my to-do list to create a more elaborate description on how to compile.
> As for 'mkdir', this works well for statically linking to libgw32c.a. If
> libgw32c.a is converted into a DLL, then indeed several such problems
appear
> at the linking stage.
It is actually unnecessary to include `mkdir' in libgw32c.a, and IMO, it
is probably undesirable. MinGW -- possibly even msvcrt.dll itself --
already provides an implementation of `mkdir', which, when called, is
redirected to msvcrt/dll's `_mkdir' function; the prototypes for both
of these are defined in MinGW's `io.h' as:
_CRTIMP int __cdecl _mkdir (const char*);
_CRTIMP int __cdecl mkdir (const char*);
whereas, most GNU packages will expect conformance with POSIX semantics,
having a prototype something like:
extern int mkdir (const char *path, mode_t mode);
Thus, when we compile a GNU package with MinGW, we need to override the
`io.h' prototype with a POSIX compliant declaration, such as the example
which may be found in groff's `nonposix.h':
#if defined(__MSDOS__) || defined(__EMX__) \
|| (defined(_WIN32) && !defined(_UWIN) && !defined(__CYGWIN__))
.
.
# define mkdir(p,m) _mkdir(p)
.
.
#endif
In this way, any reference to mkdir( path, mode ) in the source is
mapped by the compiler to _mkdir( path ), and there is absolutely no need
to provide any wrapper function, in any statically linked library.
There are many other functions which can be handled in a similar manner;
suitable prototype overrides for several of them can also be found in
groff's `nonposix.h'.
IMO, this approach, as adopted by groff, is the most appropriate method
for handling the idiosyncrasies of differing operating platforms -- place
*all* the non-standard stuff in a single header file, and #include it as
the *last* included header, in *every* source file. Of course, this means
that it becomes necessary to patch the source packages, to accommodate
this strategy. In an ideal GNU world, there would be *one* standard
`nonposix.h' file, shared by *all* GNU projects, and all GNU sources
would already #include it -- unfortunately, even the GNU world
isn't this ideal.
Best regards,
Keith.
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