在Linux上使用MinGW编译适用于Windows的Gnu11

Question

I have a C program; it compiles and links with gcc -std=gnu11 iter.c -o iter because I am using some GNU string.h extensions like strndup , strnlen and strsep .

I want to compile this program for Windows using the package i686-w64-mingw32-gcc on Ubuntu Linux.

$ i686-w64-mingw32-gcc -std=gnu11 iter.c -o iter32.exe 
In file included from iter.c:1:0:
iter.h: In function ‘str_chomp’:
iter.h:166:15: warning: implicit declaration of function ‘strndup’ [-Wimplicit-function-declaration]
   char* new = strndup(str, MAX_STR_LEN);
               ^
iter.h:166:15: warning: incompatible implicit declaration of built-in function ‘strndup’
iter.h: In function ‘str_split’:
iter.h:189:19: warning: incompatible implicit declaration of built-in function ‘strndup’
       *str_copy = strndup(str, MAX_STR_LEN);
                   ^
iter.h:211:26: warning: implicit declaration of function ‘strsep’ [-Wimplicit-function-declaration]
     for (i = 0; (token = strsep(&str_copy, delim_str)) != NULL; i++) {
                          ^
iter.h:211:24: warning: assignment makes pointer from integer without a cast [-Wint-conversion]
     for (i = 0; (token = strsep(&str_copy, delim_str)) != NULL; i++) {
                        ^
/tmp/ccPH0nG5.o:iter.c:(.text+0x216): undefined reference to `strndup'
/tmp/ccPH0nG5.o:iter.c:(.text+0x2bf): undefined reference to `strndup'
/tmp/ccPH0nG5.o:iter.c:(.text+0x3a7): undefined reference to `strsep'
collect2: error: ld returned 1 exit status

I have installed all the required MinGW runtime and libraries, but MinGW seems to ignore the -std=gnu11 directive. It's not ignoring the option entirely, because -std=asdf is "unrecognised", but it refuses to cross-compile GNU C.

Is there a way I can cross-compile for Windows a program using GNU extensions?

Answer 1

As discussed in comments, although MinGW provides many GNU programs, including GCC, it does not provide the GNU C library. C programs built by GCC for the MinGW environment rely on Microsoft's C runtime library. They can use GNU language extensions, but not, generally, GNU library extensions that are not also implemented by Microsoft. On the other hand, they can rely on Microsoft library extensions that are not implemented by GNU, though they may need to provide their own headers.

If your program relies on functions that may or may not be available in the target environment (eg Windows / MinGW) then the usual approach is to use conditional compilation directives and maybe macros to substitute alternatives to those functions in builds for targets that do not provide them. Depending on the specific function, that may mean you conditionally provide your own implementation.

How you integrate conditional compilation into your build system is a much broader question. If you are using the Autotools then facilities for this sort of thing are among its core features. You can do similar with CMake, and probably with most other popular systems. If you're using a hand-rolled build system then of course you have both the freedom and the obligation to come up with your own approach.