pipe-filter-gi: Improve GCC 11 allocation-deallocation checking

[Bruno Haible <bruno@clisp.org>]

2021-08-07  Bruno Haible  <bruno@clisp.org>

	pipe-filter-gi: Improve GCC 11 allocation-deallocation checking.
	* lib/pipe-filter.h (pipe_filter_gi_close): Move declaration up.
	(pipe_filter_gi_create): Declare that deallocation must happen through
	'pipe_filter_gi_close'.

diff --git a/lib/pipe-filter.h b/lib/pipe-filter.h
index 614b9e0..c308cf3 100644
--- a/lib/pipe-filter.h
+++ b/lib/pipe-filter.h
@@ -152,6 +152,23 @@ struct pipe_filter_ig;
 
 struct pipe_filter_gi;
 
+/* Finish reading the output via the prepare_read/done_read functions
+   specified to pipe_filter_gi_create.
+
+   Note that the prepare_read/done_read functions may be called in a
+   different thread than the current thread (depending on the platform).
+   However, they will always be called before pipe_filter_gi_close has
+   returned.
+
+   The write side of the pipe is closed as soon as pipe_filter_gi_close
+   starts, while the read side will be closed just before it finishes.
+
+   Return 0 upon success, or (only if exit_on_error is false):
+   - -1 with errno set upon failure,
+   - the positive exit code of the subprocess if that failed.  */
+extern int
+       pipe_filter_gi_close (struct pipe_filter_gi *filter);
+
 /* Create a subprocess and pipe some data through it.
    Arguments:
    - progname is the program name used in error messages.
@@ -185,7 +202,8 @@ extern struct pipe_filter_gi *
                               bool null_stderr, bool exit_on_error,
                               prepare_read_fn prepare_read,
                               done_read_fn done_read,
-                              void *private_data);
+                              void *private_data)
+  _GL_ATTRIBUTE_DEALLOC (pipe_filter_gi_close, 1);
 
 /* Write size bytes starting at buf into the pipe and in the meanwhile
    possibly call the prepare_read and done_read functions specified to
@@ -207,23 +225,6 @@ extern int
        pipe_filter_gi_write (struct pipe_filter_gi *filter,
                              const void *buf, size_t size);
 
-/* Finish reading the output via the prepare_read/done_read functions
-   specified to pipe_filter_gi_create.
-
-   Note that the prepare_read/done_read functions may be called in a
-   different thread than the current thread (depending on the platform).
-   However, they will always be called before pipe_filter_gi_close has
-   returned.
-
-   The write side of the pipe is closed as soon as pipe_filter_gi_close
-   starts, while the read side will be closed just before it finishes.
-
-   Return 0 upon success, or (only if exit_on_error is false):
-   - -1 with errno set upon failure,
-   - the positive exit code of the subprocess if that failed.  */
-extern int
-       pipe_filter_gi_close (struct pipe_filter_gi *filter);
-
 
 /* ============================ pipe_filter_gg ============================ */