OK
To get the code through a Win32 build with MSC and intel, we need to get the prototypes out. It's not a big deal really. You just need to decide what conditional to use.
My suggestion is: HAVE_ANSI_COMPILER for ANSI C issues and the
_WIN32 define for issues with the Win32 library. The good thing with _WIN32 is that it is always defined for any compiler targetting any Windows version. (note: _WIN32 not WIN32). There is no need to prepare anything, it's OK just to use it like this:

#if _WIN32
...Win32 library things
#endif

Why I say this is because the WINDOWS32 define used in make is not always consistent. So, in present code, whenever the _STDC_ is used, you will need to define WINDOWS32 as well. This is confusing because it has nothing to do with the Win32 library. To be portable it's better to use HAVE_ANSI_COMPILER and skip the _STDC_ and WINDOWS32 conditionals.

This will not work:
#if defined (_cplusplus) || (defined (__STDC_) && _STDC_)

but this will:
#if defined (_cplusplus) || (defined (__STDC_) && _STDC_) || defined (WINDOWS32)

as well as this:
#if defined (__cplusplus) || defined (HAVE_ANSI_COMPILER)

on the other hand this should never be allowed to work:
#if defined HAVE_UNISTD_H

could be used to indicate a UNIX-system

That's my thoughts

regards JB

PS: Details by bug reports on each issue

Obviously the compiler need the prototypes in <direct.h>, which is the only system include file where these functions are declared. It is not a good solution to replace the prototypes with application defined ones.

Which leeds us to my mention about "bogus" prototypes. The compiler don't like them and do not need them. The whole idea of redeclare runtime functions seems very strange to me. I proposed two solutions which will satisfy the Microsoft compiler, but the issue is not mine. There is apparently someone who needs these prototypes (which compiler is that?) and a solution is better made by someone who knows what it is all about. I simply commented them out to succeed in my build.

make.h is not included in all source files. Is it not a good idea to move all conditionals and declarations to make.h and include make.h in all source files? I think project maintenance will benefit greatly in the long run on this.

regards Jerker

When compiling with Microsoft or intel compiler using the Microsoft C runtime library, the following library functions are not declared: chdir, getcwd

They are declared in <direct.h> like this:
_CRTIMP int __cdecl _chdir(const char*);
_CRTIMP char* __cdecl _getcwd(char*, int);

Without direct.h make will define the following incorrect prototypes:
main.c(77):     extern int chdir ();
make.h(488):    extern char *getcwd ();

leading to at least fatal linking errors.

solution:
Add the following in make.h
#if defined(MSC_VER) || defined(__BORLANDC_)
#include <direct.h>
#endif

Related to this is also some (in this context) bogus prototype declarations at:
commands.c(36):     getpid
dir.c(1163):        stat
fnmatch.c(123)      getenv
getopt.c(209):      getenv
main.c(77):         chdir
main.c(834):        mktemp
make.h(289):        strerror
make.h(488):        getcwd
make.h(497):        environ
job.c(178):         dup2
job.c(179):         execve
job.c(180):         _exit
read.c(2922):       getenv

I suggest that these will be moved to make.h and protected with a conditional like:
#if defined(HAVE_GETENV) && defined(NEED_PROTOTYPE)
extern char *getenv ();
#endif

A solution could also be:
in the beginning of make.h
#ifdef  __cplusplus
extern "C" {
#endif

in the end of make.h
#ifdef  __cplusplus
}
#endif

regards Jerker