Disable -Werror=implicit-fallthrough on GCC7 and later.  Taken from upstream:
https://github.com/Tencent/rapidjson/commit/fe19b7b6016d446722621fb407738209d1a911e8
https://github.com/Tencent/rapidjson/commit/cba45fe9de6923b858edb0780e257b7257aa4f7b

diff --git a/include/rapidjson/internal/regex.h b/include/rapidjson/internal/regex.h
index 422a5240..d4039716 100644
--- a/include/rapidjson/internal/regex.h
+++ b/include/rapidjson/internal/regex.h
@@ -29,6 +29,9 @@ RAPIDJSON_DIAG_OFF(implicit-fallthrough)
 #ifdef __GNUC__
 RAPIDJSON_DIAG_PUSH
 RAPIDJSON_DIAG_OFF(effc++)
+#if __GNUC__ >= 7
+RAPIDJSON_DIAG_OFF(implicit-fallthrough)
+#endif
 #endif
 
 #ifdef _MSC_VER
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<tr><td><span title='2024-04-03 17:18:38 +0100'>2024-04-03</span></td><td><a href='/guix/commit/gnu/installer/newt?id=ac19e038b457d0585812091200005befd9b29259'>Switch order of the default substitute servers.</a><span class='msg-avail'>...<span class='msg-tooltip'>The aim here is to improve the user experience.  There's anecdotal evidence
that the network performance for bordeaux is better compared to ci at least
for some users, and I don't know of any issues with rate limiting or access
restriction for bordeaux compared to ci.  It also has IPv6 support.

Additionally, bordeaux generally had more substitutes than ci, particularly
for aarch64-linux and armhf-linux.  This change will offer a very slight
speedup for those substitutes that only bordeaux has.

Bordeaux has been a default substitute server for nearly 3 years now and I
think this change is overdue.  I'm also hopeful that we'll be able to build on
the testing regarding mirrors for bordeaux, and that'll allow potentially
improving the hosting setup (through providing more redundancy) and further
improving substitute fetching for users who currently have issues with
substitute access.

* config-daemon.ac: Switch substitute urls order.
* doc/guix.texi: Ditto.
* etc/guix-install.sh: Ditto.
* gnu/installer/newt/network.scm (wait-service-online): Ditto.
* guix/store.scm (%default-substitute-urls): Ditto.

Change-Id: I4f6d93ae1fc8b03d80b47b18b5749a51f1fde17b
Signed-off-by: Christopher Baines &lt;mail@cbaines.net&gt;
</span></span></td><td>Christopher Baines</td></tr>