+ AC_DEFINE([VOID_UNSETENV], [1], [Define to 1 if unsetenv returns void
+ instead of int.])
+ REPLACE_UNSETENV=1
+ AC_LIBOBJ([unsetenv])
+ fi
+
+ dnl Solaris 10 unsetenv does not remove all copies of a name.
+ dnl OpenBSD 4.7 unsetenv("") does not fail.
+ AC_CACHE_CHECK([whether unsetenv obeys POSIX],
+ [gl_cv_func_unsetenv_works],
+ [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
+ #include <stdlib.h>
+ #include <errno.h>
+ ]], [[
+ char entry[] = "b=2";
+ if (putenv ((char *) "a=1")) return 1;
+ if (putenv (entry)) return 2;
+ entry[0] = 'a';
+ unsetenv ("a");
+ if (getenv ("a")) return 3;
+ if (!unsetenv ("") || errno != EINVAL) return 4;
+ ]])],
+ [gl_cv_func_unsetenv_works=yes], [gl_cv_func_unsetenv_works=no],
+ [gl_cv_func_unsetenv_works="guessing no"])])
+ if test "$gl_cv_func_unsetenv_works" != yes; then
+ REPLACE_UNSETENV=1
+ AC_LIBOBJ([unsetenv])