- define([gt_cv_var], [gt_cv_var_]$2[_declaration])
- AC_MSG_CHECKING([if $2 is properly declared])
- AC_CACHE_VAL(gt_cv_var, [
- AC_TRY_COMPILE([$1
- extern struct { int foo; } $2;],
- [$2.foo = 1;],
- gt_cv_var=no,
- gt_cv_var=yes)])
- AC_MSG_RESULT($gt_cv_var)
- if test $gt_cv_var = yes; then
- AC_DEFINE([HAVE_]translit($2, [a-z], [A-Z])[_DECL], 1,
- [Define if you have the declaration of $2.])
+ AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
+ AC_CHECK_FUNCS([unsetenv])
+ if test $ac_cv_func_unsetenv = no; then
+ HAVE_UNSETENV=0
+ AC_LIBOBJ([unsetenv])
+ gl_PREREQ_UNSETENV
+ else
+ AC_CACHE_CHECK([for unsetenv() return type], gt_cv_func_unsetenv_ret,
+ [AC_TRY_COMPILE([#include <stdlib.h>
+extern
+#ifdef __cplusplus
+"C"
+#endif
+#if defined(__STDC__) || defined(__cplusplus)
+int unsetenv (const char *name);
+#else
+int unsetenv();
+#endif
+], , gt_cv_func_unsetenv_ret='int', gt_cv_func_unsetenv_ret='void')])
+ if test $gt_cv_func_unsetenv_ret = 'void'; then
+ VOID_UNSETENV=1
+ fi