docs/style: permit inline loop variables

I've already wasted enough of my time debugging aliased variables in
deeply nested loops. While not scattering variable declarations around
is a good aim I think we can make an exception for stuff used inside a
loop.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20230829161528.2707696-5-alex.bennee@linaro.org>

docs/devel/style.rst

@@ -204,7 +204,14 @@ Declarations
 
 Mixed declarations (interleaving statements and declarations within
 blocks) are generally not allowed; declarations should be at the beginning
-of blocks.
+of blocks. To avoid accidental re-use it is permissible to declare
+loop variables inside for loops:
+
+.. code-block:: c
+
+    for (int i = 0; i < ARRAY_SIZE(thing); i++) {
+        /* do something loopy */
+    }
 
 Every now and then, an exception is made for declarations inside a
 #ifdef or #ifndef block: if the code looks nicer, such declarations can