Re: [PATCH 01/46] error: Improve examples in error.h's big comment

[Greg Kurz]

On Wed, 24 Jun 2020 18:42:59 +0200
Markus Armbruster <armbru@redhat.com> wrote:

> 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>
> ---
>  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..1a5ea25e12 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:
> @@ -108,12 +108,23 @@
>   *     }
>   *
>   * Do *not* "optimize" this to
> + *     Error *err = NULL;
>   *     foo(arg, &err);
>   *     bar(arg, &err); // WRONG!
>   *     if (err) {
>   *         handle the error...
>   *     }
>   * because this may pass a non-null err to bar().
> + *
> + * Likewise, do *not*
> + *     Error *err = NULL;
> + *     if (cond1) {
> + *         error_setg(err, ...);

s/err/&err

> + *     }
> + *     if (cond2) {
> + *         error_setg(err, ...); // WRONG!

ditto

With that fixed:

Reviewed-by: Greg Kurz <groug@kaod.org>

> + *     }
> + * because this may pass a non-null err to error_setg().
>   */
>  
>  #ifndef ERROR_H