Put more information about failed tests into the test return codes. * m4/c-stack.m4 (AC_SYS_XSI_STACK_OVERFLOW_HEURISTIC): Change test program so that it returns an enumerated value (0, 1, 2, 3, 4, ...). * m4/d-ino.m4 (gl_CHECK_TYPE_STRUCT_DIRENT_D_INO): Likewise. * m4/getcwd-path-max.m4 (gl_FUNC_GETCWD_PATH_MAX): Likewise. * m4/getcwd.m4 (gl_FUNC_GETCWD_NULL): Likewise. * m4/getdelim.m4 (gl_FUNC_GETDELIM): Likewise. * m4/getline.m4 (gl_FUNC_GETLINE): Likewise. * m4/intdiv0.m4 (gt_INTDIV0): Likewise. * m4/isapipe.m4 (gl_PREREQ_ISAPIPE): Likewise. * m4/nanosleep.m4 (gl_FUNC_NANOSLEEP): Likewise. * m4/posix_spawn.m4 (gl_POSIX_SPAWN_WORKS): Likewise. * m4/putenv.m4 (gl_FUNC_PUTENV): Likewise. * m4/sleep.m4 (gl_FUNC_SLEEP): Likewise. * m4/stdint.m4 (gl_STDINT_H): Likewise. * m4/calloc.m4 (_AC_FUNC_CALLOC_IF): Change test program so that it returns a bit mask. * m4/canonicalize.m4 (gl_FUNC_REALPATH_WORKS): Likewise. * m4/chown.m4 (gl_FUNC_CHOWN_FOLLOWS_SYMLINK): Likewise. * m4/dup2.m4 (gl_FUNC_DUP2): Likewise. * m4/fcntl-o.m4 (gl_FCNTL_O_FLAGS): Likewise. * m4/fnmatch.m4 (gl_FUNC_FNMATCH_POSIX): Likewise. * m4/frexp.m4 (gl_FUNC_FREXP_WORKS): Likewise. * m4/frexpl.m4 (gl_FUNC_FREXPL_WORKS): Likewise. * m4/getopt.m4 (gl_GETOPT_CHECK_HEADERS): Likewise. * m4/iconv.m4 (AM_ICONV_LINK): Likewise. * m4/iconv_open.m4 (gl_FUNC_ICONV_OPEN_UTF): Likewise. * m4/isfinite.m4 (gl_ISFINITEL_WORKS): Likewise. * m4/isnanf.m4 (gl_ISNANF_WORKS): Likewise. * m4/isnanl.m4 (gl_FUNC_ISNANL_WORKS): Likewise. * m4/ldexpl.m4 (gl_FUNC_LDEXPL_WORKS): Likewise. * m4/link.m4 (gl_FUNC_LINK): Likewise. * m4/linkat.m4 (gl_FUNC_LINKAT): Likewise. * m4/mbrlen.m4 (gl_MBRLEN_RETVAL): Likewise. * m4/mbrtowc.m4 (gl_MBRTOWC_RETVAL): Likewise. * m4/mbsrtowcs.m4 (gl_MBSRTOWCS_WORKS): Likewise. * m4/memchr.m4 (gl_FUNC_MEMCHR): Likewise. * m4/memmem.m4 (gl_FUNC_MEMMEM): Likewise. * m4/mkfifo.m4 (gl_FUNC_MKFIFO): Likewise. * m4/mkstemp.m4 (gl_FUNC_MKSTEMP): Likewise. * m4/mktime.m4 (AC_FUNC_MKTIME): Likewise. * m4/open.m4 (gl_FUNC_OPEN): Likewise. * m4/poll.m4 (gl_FUNC_POLL): Likewise. * m4/popen.m4 (gl_FUNC_POPEN): Likewise. * m4/printf.m4 (gl_PRINTF_SIZES_C99, gl_PRINTF_LONG_DOUBLE, gl_PRINTF_INFINITE, gl_PRINTF_INFINITE_LONG_DOUBLE, gl_PRINTF_DIRECTIVE_A, gl_PRINTF_DIRECTIVE_F, gl_PRINTF_DIRECTIVE_LS, gl_PRINTF_PRECISION): Likewise. * m4/regex.m4 (gl_REGEX): Likewise. * m4/rename.m4 (gl_FUNC_RENAME): Likewise. * m4/rmdir.m4 (gl_FUNC_RMDIR): Likewise. * m4/setenv.m4 (gl_FUNC_SETENV_SEPARATE): Likewise. * m4/stat.m4 (gl_FUNC_STAT): Likewise. * m4/stpncpy.m4 (gl_FUNC_STPNCPY): Likewise. * m4/strcasestr.m4 (gl_FUNC_STRCASESTR): Likewise. * m4/strerror_r.m4 (gl_FUNC_STRERROR_R): Likewise. * m4/strsignal.m4 (gl_FUNC_STRSIGNAL): Likewise. * m4/strstr.m4 (gl_FUNC_STRSTR): Likewise. * m4/strtod.m4 (gl_FUNC_STRTOD): Likewise. * m4/symlink.m4 (gl_FUNC_SYMLINK): Likewise. * m4/tsearch.m4 (gl_FUNC_TSEARCH): Likewise. * m4/ttyname_r.m4 (gl_FUNC_TTYNAME_R): Likewise. * m4/unlink-busy.m4 (gl_FUNC_UNLINK_BUSY_TEXT): Likewise. * m4/unlink.m4 (gl_FUNC_UNLINK): Likewise. * m4/utimensat.m4 (gl_FUNC_UTIMENSAT): Likewise. * m4/utimes.m4 (gl_FUNC_UTIMES): Likewise. * m4/wcrtomb.m4 (gl_FUNC_WCRTOMB): Likewise. * m4/wcwidth.m4 (gl_FUNC_WCWIDTH): Likewise. * m4/signbit.m4 (gl_SIGNBIT_TEST_PROGRAM): Likewise. (gl_FLOATTYPE_SIGN_LOCATION): Change test program so that it returns an enumerated value. * m4/acl.m4 (gl_ACL_GET_FILE): Use "if ... return 1; return 0;" style.

--- a/m4/linkat.m4
+++ b/m4/linkat.m4
@@ -1,4 +1,4 @@
-# serial 3
+# serial 4
 # See if we need to provide linkat replacement.
 
 dnl Copyright (C) 2009-2010 Free Software Foundation, Inc.
@@ -50,9 +50,8 @@
               #include <errno.h>
               #include <stdio.h>
             ]],
-            [[int fd;
-              int err;
-              int ret;
+            [[int result;
+              int fd;
               /* Create a regular file.  */
               fd = open ("conftest.a", O_CREAT | O_EXCL | O_WRONLY, 0600);
               if (fd < 0)
@@ -66,14 +65,15 @@
               if (linkat (AT_FDCWD, "conftest.a", AT_FDCWD, "conftest.b",
                           AT_SYMLINK_FOLLOW) < 0)
                 return 0;
+              result = 0;
               /* Test whether a trailing "/" is treated like "/.".  */
               if (linkat (AT_FDCWD, "conftest.a/", AT_FDCWD, "conftest.c",
                           AT_SYMLINK_FOLLOW) == 0)
-                return 4;
+                result |= 4;
               if (linkat (AT_FDCWD, "conftest.a", AT_FDCWD, "conftest.d/",
                           AT_SYMLINK_FOLLOW) == 0)
-                return 5;
-              return 0;
+                result |= 8;
+              return result;
             ]])],
          [gl_cv_func_linkat_slash=yes],
          [gl_cv_func_linkat_slash=no],