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From fe7dd779a9674dc54ffe296247ae6559f2b55b22 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= <marcandre.lureau@redhat.com>
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Date: Wed, 16 Dec 2020 16:06:07 -0500
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Subject: [PATCH 06/14] error: Fix examples in error.h's big comment
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Author: Marc-André Lureau <marcandre.lureau@redhat.com>
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Message-id: <20201216160615.324213-3-marcandre.lureau@redhat.com>
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Patchwork-id: 100473
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O-Subject: [RHEL-8.4.0 qemu-kvm PATCH v2 02/10] error: Fix examples in error.h's big comment
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Bugzilla: 1859494
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RH-Acked-by: Danilo de Paula <ddepaula@redhat.com>
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RH-Acked-by: Sergio Lopez Pascual <slp@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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From: Markus Armbruster <armbru@redhat.com>
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Mark a bad example more clearly.  Fix the error_propagate_prepend()
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example.  Add a missing declaration and a second error pileup example.
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Signed-off-by: Markus Armbruster <armbru@redhat.com>
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Reviewed-by: Eric Blake <eblake@redhat.com>
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Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
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Reviewed-by: Greg Kurz <groug@kaod.org>
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Message-Id: <20200707160613.848843-2-armbru@redhat.com>
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(cherry picked from commit 47ff5ac81e8bb3096500de7b132051691d533d36)
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Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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 include/qapi/error.h | 16 ++++++++++++++--
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 1 file changed, 14 insertions(+), 2 deletions(-)
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diff --git a/include/qapi/error.h b/include/qapi/error.h
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index 3f95141a01a..83c38f9a188 100644
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--- a/include/qapi/error.h
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+++ b/include/qapi/error.h
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@@ -24,7 +24,7 @@
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  *                       "charm, top, bottom.\n");
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  *
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  * Do *not* contract this to
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- *     error_setg(&err, "invalid quark\n"
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+ *     error_setg(&err, "invalid quark\n" // WRONG!
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  *                "Valid quarks are up, down, strange, charm, top, bottom.");
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  *
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  * Report an error to the current monitor if we have one, else stderr:
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@@ -52,7 +52,8 @@
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  * where Error **errp is a parameter, by convention the last one.
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  *
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  * Pass an existing error to the caller with the message modified:
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- *     error_propagate_prepend(errp, err);
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+ *     error_propagate_prepend(errp, err,
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+ *                             "Could not frobnicate '%s': ", name);
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  *
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  * Avoid
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  *     error_propagate(errp, err);
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@@ -108,12 +109,23 @@
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  *     }
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  *
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  * Do *not* "optimize" this to
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+ *     Error *err = NULL;
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  *     foo(arg, &err;;
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  *     bar(arg, &err;; // WRONG!
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  *     if (err) {
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  *         handle the error...
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  *     }
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  * because this may pass a non-null err to bar().
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+ *
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+ * Likewise, do *not*
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+ *     Error *err = NULL;
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+ *     if (cond1) {
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+ *         error_setg(&err, ...);
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+ *     }
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+ *     if (cond2) {
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+ *         error_setg(&err, ...); // WRONG!
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+ *     }
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+ * because this may pass a non-null err to error_setg().
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  */
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 #ifndef ERROR_H
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-- 
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2.27.0
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