+])
+
+# Check whether realpath works. Assume that if a platform has both
+# realpath and canonicalize_file_name, but the former is broken, then
+# so is the latter.
+AC_DEFUN([gl_FUNC_REALPATH_WORKS],
+[
+ AC_CHECK_FUNCS_ONCE([realpath])
+ AC_CACHE_CHECK([whether realpath works], [gl_cv_func_realpath_works], [
+ touch conftest.a
+ mkdir conftest.d
+ AC_RUN_IFELSE([
+ AC_LANG_PROGRAM([[
+ ]GL_NOCRASH[
+ #include <stdlib.h>
+ #include <string.h>
+ ]], [[
+ int result = 0;
+ {
+ char *name = realpath ("conftest.a", NULL);
+ if (!(name && *name == '/'))
+ result |= 1;
+ }
+ {
+ char *name = realpath ("conftest.b/../conftest.a", NULL);
+ if (name != NULL)
+ result |= 2;
+ }
+ {
+ char *name = realpath ("conftest.a/", NULL);
+ if (name != NULL)
+ result |= 4;
+ }
+ {
+ char *name1 = realpath (".", NULL);
+ char *name2 = realpath ("conftest.d//./..", NULL);
+ if (strcmp (name1, name2) != 0)
+ result |= 8;
+ }
+ return result;
+ ]])
+ ], [gl_cv_func_realpath_works=yes], [gl_cv_func_realpath_works=no],
+ [gl_cv_func_realpath_works="guessing no"])
+ rm -rf conftest.a conftest.d
+ ])
+ if test "$gl_cv_func_realpath_works" = yes; then
+ AC_DEFINE([FUNC_REALPATH_WORKS], [1], [Define to 1 if realpath()
+ can malloc memory, always gives an absolute path, and handles
+ trailing slash correctly.])
+ fi