Re: [PATCH v3 01/44] error: Improve examples in error.h's big comment

[Markus Armbruster]

Markus Armbruster <armbru@redhat.com> writes:

> Show errp instead of &err where &err is actually unusual.  Add a
> missing declaration.  Add a second error pileup example.
>
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> Reviewed-by: Eric Blake <eblake@redhat.com>
> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> Reviewed-by: Greg Kurz <groug@kaod.org>
> ---
>  include/qapi/error.h | 19 +++++++++++++++----
>  1 file changed, 15 insertions(+), 4 deletions(-)
>
> diff --git a/include/qapi/error.h b/include/qapi/error.h
> index ad5b6e896d..3e64324b7a 100644
> --- a/include/qapi/error.h
> +++ b/include/qapi/error.h
> @@ -16,15 +16,15 @@
>   * Error reporting system loosely patterned after Glib's GError.
>   *
>   * Create an error:
> - *     error_setg(&err, "situation normal, all fouled up");
> + *     error_setg(errp, "situation normal, all fouled up");
>   *
>   * Create an error and add additional explanation:
> - *     error_setg(&err, "invalid quark");
> - *     error_append_hint(&err, "Valid quarks are up, down, strange, "
> + *     error_setg(errp, "invalid quark");
> + *     error_append_hint(errp, "Valid quarks are up, down, strange, "
>   *                       "charm, top, bottom.\n");
>   *
>   * Do *not* contract this to
> - *     error_setg(&err, "invalid quark\n"
> + *     error_setg(errp, "invalid quark\n" // WRONG!
>   *                "Valid quarks are up, down, strange, charm, top, bottom.");
>   *
>   * Report an error to the current monitor if we have one, else stderr:

I intend to drop the change from &err to errp, and update the commit
message accordingly.

error_setg(&err, ...) is indeed unusual, and I cleaned up several unwise
uses in PATCH 32+35+39.  However, error_append_hint(errp, ...) is bad
advice until Vladimir's ERRP_AUTO_PROPAGATE() makes it work.  No need to
get ahead of his work here.

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