Re: [PATCH] Use xattr (Linux) in qcopy-acl.c

[Bruno Haible]

I wrote:
>       * modules/qcopy-acl (Depends-on): Add condition.
>       (configure.ac): Set QCOPY_ACL_LIB.
>       (Link): Add $(QCOPY_ACL_LIB). Remove $(LIB_ACL).

Oops, this has a mistake. The variable LIB_ACL needs to be initialized
before the code uses its value; otherwise $LIB_ACL will come out as empty.
The way to order the initialization is to use AC_REQUIRE of the macro
which defines LIB_ACL. Then, since invocation and AC_REQUIRE of a macro
defined through AC_DEFUN triggers an autoconf warning, one needs AC_DEFUN_ONCE
instead.


2023-01-13  Bruno Haible  <bruno@clisp.org>

        qcopy-acl: Make last patch more robust.
        * m4/acl.m4 (gl_FUNC_ACL): Define through AC_DEFUN_ONCE.
        * modules/qcopy-acl (configure.ac): Require gl_FUNC_ACL.

diff --git a/m4/acl.m4 b/m4/acl.m4
index e612f1ae34..dc9853a156 100644
--- a/m4/acl.m4
+++ b/m4/acl.m4
@@ -1,5 +1,5 @@
 # acl.m4 - check for access control list (ACL) primitives
-# serial 26
+# serial 27
 
 # Copyright (C) 2002, 2004-2023 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
@@ -17,7 +17,7 @@ AC_DEFUN([gl_FUNC_ACL_ARG],
 ])
 
 
-AC_DEFUN([gl_FUNC_ACL],
+AC_DEFUN_ONCE([gl_FUNC_ACL],
 [
   AC_REQUIRE([gl_FUNC_ACL_ARG])
   AC_CHECK_FUNCS_ONCE([fchmod])
diff --git a/modules/qcopy-acl b/modules/qcopy-acl
index 8dd147927d..b89d8ecab6 100644
--- a/modules/qcopy-acl
+++ b/modules/qcopy-acl
@@ -10,6 +10,7 @@ acl-permissions [test "$use_xattr" != yes]
 
 configure.ac:
 gl_FUNC_XATTR
+AC_REQUIRE([gl_FUNC_ACL])
 if test "$use_xattr" = yes; then
   QCOPY_ACL_LIB="$LIB_XATTR"
 else