ilya@www ~/tmp $ gcc -Dchar=wchar_t -Dprintf=wprintf test.c
In file included from /usr/include/stdio.h:35:0,
                 from test.c:1:
/usr/include/bits/types.h:30:23: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘__u_char’
 typedef unsigned char __u_char;
                       ^~~~~~~~
/usr/include/bits/types.h:36:21: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘__int8_t’
 typedef signed char __int8_t;
                     ^~~~~~~~
/usr/include/bits/types.h:37:23: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘__uint8_t’
 typedef unsigned char __uint8_t;
                       ^~~~~~~~~
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
In file included from /usr/include/stdio.h:41:0,
                 from test.c:1:
/usr/include/libio.h:275:15: error: expected ‘:’, ‘,’, ‘;’, ‘}’ or ‘__attribute__’ before ‘_vtable_offset’
   signed char _vtable_offset;
               ^~~~~~~~~~~~~~
<command-line>:0:6: error: unknown type name ‘wchar_t’; did you mean ‘char’?
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’; did you mean ‘char’?
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’; did you mean ‘char’?
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’; did you mean ‘char’?
<command-line>:0:6: error: unknown type name ‘wchar_t’; did you mean ‘char’?
<command-line>:0:6: error: unknown type name ‘wchar_t’; did you mean ‘char’?
<command-line>:0:6: error: unknown type name ‘wchar_t’; did you mean ‘char’?
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’; did you mean ‘char’?
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’; did you mean ‘char’?
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’; did you mean ‘char’?
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’; did you mean ‘char’?
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
In file included from test.c:1:0:
/usr/include/stdio.h:367:6: error: format string argument is not a string type
      __attribute__ ((__format__ (__printf__, 2, 0)));
      ^~~~~~~~~~~~~
<command-line>:0:6: error: unknown type name ‘wchar_t’
In file included from test.c:1:0:
/usr/include/stdio.h:369:6: error: format string argument is not a string type
      __attribute__ ((__format__ (__printf__, 2, 3)));
      ^~~~~~~~~~~~~
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
In file included from /usr/include/features.h:423:0,
                 from /usr/include/bits/libc-header-start.h:33,
                 from /usr/include/stdio.h:27,
                 from test.c:1:
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
In file included from test.c:1:0:
/usr/include/stdio.h:422:6: error: format string argument is not a string type
      __attribute__ ((__format__ (__scanf__, 2, 0))) __wur;
      ^~~~~~~~~~~~~
<command-line>:0:6: error: unknown type name ‘wchar_t’
In file included from test.c:1:0:
/usr/include/stdio.h:429:6: error: format string argument is not a string type
      __attribute__ ((__format__ (__scanf__, 1, 0))) __wur;
      ^~~~~~~~~~~~~
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
In file included from test.c:1:0:
/usr/include/stdio.h:434:6: error: format string argument is not a string type
      __THROW __attribute__ ((__format__ (__scanf__, 2, 0)));
      ^~~~~~~
In file included from /usr/include/features.h:423:0,
                 from /usr/include/bits/libc-header-start.h:33,
                 from /usr/include/stdio.h:27,
                 from test.c:1:
<command-line>:0:6: error: unknown type name ‘wchar_t’
In file included from test.c:1:0:
/usr/include/stdio.h:447:6: error: format string argument is not a string type
      __attribute__ ((__format__ (__scanf__, 2, 0))) __wur;
      ^~~~~~~~~~~~~
In file included from /usr/include/features.h:423:0,
                 from /usr/include/bits/libc-header-start.h:33,
                 from /usr/include/stdio.h:27,
                 from test.c:1:
<command-line>:0:6: error: unknown type name ‘wchar_t’
In file included from test.c:1:0:
/usr/include/stdio.h:450:6: error: format string argument is not a string type
      __attribute__ ((__format__ (__scanf__, 1, 0))) __wur;
      ^~~~~~~~~~~~~
In file included from /usr/include/features.h:423:0,
                 from /usr/include/bits/libc-header-start.h:33,
                 from /usr/include/stdio.h:27,
                 from test.c:1:
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
In file included from test.c:1:0:
/usr/include/stdio.h:455:6: error: format string argument is not a string type
      __attribute__ ((__format__ (__scanf__, 2, 0)));
      ^~~~~~~~~~~~~
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’; did you mean ‘char’?
<command-line>:0:6: error: unknown type name ‘wchar_t’; did you mean ‘char’?
<command-line>:0:6: error: unknown type name ‘wchar_t’; did you mean ‘char’?
<command-line>:0:6: error: unknown type name ‘wchar_t’; did you mean ‘char’?
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’
<command-line>:0:6: error: unknown type name ‘wchar_t’; did you mean ‘char’?
In file included from /usr/include/stdlib.h:279:0,
                 from test.c:2:
/usr/include/sys/types.h:33:9: error: unknown type name ‘__u_char’
 typedef __u_char u_char;
         ^~~~~~~~
In file included from /usr/include/sys/types.h:156:0,
                 from /usr/include/stdlib.h:279,
                 from test.c:2:
/usr/include/bits/stdint-intn.h:24:9: error: unknown type name ‘__int8_t’
 typedef __int8_t int8_t;
         ^~~~~~~~
In file included from /usr/include/bits/thread-shared-types.h:77:0,
                 from /usr/include/bits/pthreadtypes.h:23,
                 from /usr/include/sys/types.h:245,
                 from /usr/include/stdlib.h:279,
                 from test.c:2:
/usr/include/bits/pthreadtypes-arch.h:76:15: error: expected ‘:’, ‘,’, ‘;’, ‘}’ or ‘__attribute__’ before ‘__rwelision’
   signed char __rwelision;
               ^~~~~~~~~~~
test.c: In function ‘main’:
test.c:7:20: warning: initialization from incompatible pointer type [-Wincompatible-pointer-types]
  char *i, *s, *a = "линукс12";
                    ^~~~~~~~~~~~~~~~
test.c:8:7: warning: type defaults to ‘int’ in declaration of ‘c’ [-Wimplicit-int]
  auto c;
       ^
test.c:9:14: warning: comparison between pointer and integer
  for(i = 0;i < sizeof(a);) {
              ^
test.c:10:5: warning: assignment makes integer from pointer without a cast [-Wint-conversion]
   c = i; free(heap);
     ^
test.c:15:16: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
    *++s, *--s, (int) i++ & 0