compiling ./missing/crypt.c
./missing/crypt.c:948:1: error: conflicting types for ‘encrypt’
 encrypt(block, flag)
 ^
In file included from /usr/include/sys/reent.h:13:0,
                 from /usr/include/math.h:5,
                 from ./include/ruby/missing.h:23,
                 from ./missing/crypt.c:37:
/usr/include/sys/unistd.h:53:6: note: previous declaration of ‘encrypt’ was here
 void _EXFUN(encrypt, (char *__block, int __edflag));
      ^
make: *** [Makefile:364: crypt.o] Error 1

***** ALSO MANY WARNINGS *****

compiling file.c
file.c: In function ‘rb_file_readable_p’:
file.c:1551:9: warning: implicit declaration of function ‘eaccess’ [-Wimplicit-function-declaration]
     if (eaccess(StringValueCStr(fname), R_OK) < 0) return Qfalse;
         ^

compiling string.c
string.c: In function ‘rb_str_enumerate_chars’:
string.c:6883:3: warning: ‘ary’ may be used uninitialized in this function [-Wmaybe-uninitialized]
   rb_ary_push(ary, substr);
   ^

compiling thread.c
In file included from ./include/ruby/ruby.h:36:0,
                 from eval_intern.h:4,
                 from thread.c:60:
thread.c: In function ‘rb_thread_fd_select’:
./include/ruby/defines.h:113:15: warning: ‘orig_except.fdset’ may be used uninitialized in this function [-Wmaybe-uninitialized]
 #define xfree ruby_xfree
               ^
In file included from method.h:14:0,
                 from vm_core.h:24,
                 from eval_intern.h:5,
                 from thread.c:60:
thread.c:3425:34: note: ‘orig_except.fdset’ was declared here
     rb_fdset_t UNINITIALIZED_VAR(orig_except);
                                  ^
internal.h:40:30: note: in definition of macro ‘UNINITIALIZED_VAR’
 #define UNINITIALIZED_VAR(x) x __attribute__((unused))
                              ^
In file included from ./include/ruby/ruby.h:36:0,
                 from eval_intern.h:4,
                 from thread.c:60:
./include/ruby/defines.h:113:15: warning: ‘orig_write.fdset’ may be used uninitialized in this function [-Wmaybe-uninitialized]
 #define xfree ruby_xfree
               ^
In file included from method.h:14:0,
                 from vm_core.h:24,
                 from eval_intern.h:5,
                 from thread.c:60:
thread.c:3424:34: note: ‘orig_write.fdset’ was declared here
     rb_fdset_t UNINITIALIZED_VAR(orig_write);
                                  ^
internal.h:40:30: note: in definition of macro ‘UNINITIALIZED_VAR’
 #define UNINITIALIZED_VAR(x) x __attribute__((unused))
                              ^
In file included from ./include/ruby/ruby.h:36:0,
                 from eval_intern.h:4,
                 from thread.c:60:
./include/ruby/defines.h:113:15: warning: ‘orig_read.fdset’ may be used uninitialized in this function [-Wmaybe-uninitialized]
 #define xfree ruby_xfree
               ^
In file included from method.h:14:0,
                 from vm_core.h:24,
                 from eval_intern.h:5,
                 from thread.c:60:
thread.c:3423:34: note: ‘orig_read.fdset’ was declared here
     rb_fdset_t UNINITIALIZED_VAR(orig_read);
                                  ^
internal.h:40:30: note: in definition of macro ‘UNINITIALIZED_VAR’
 #define UNINITIALIZED_VAR(x) x __attribute__((unused))