compat/regex: explicitly mark intentional use of the comma operator

The comma operator is a somewhat obscure C feature that is often used by
mistake and can even cause unintentional code flow. That is why the
`-Wcomma` option of clang was introduced: To identify unintentional uses
of the comma operator.

In the `compat/regex/` code, the comma operator is used twice, once to
avoid surrounding two conditional statements with curly brackets, the
other one to increment two counters simultaneously in a `do ... while`
condition.

The first one is replaced with a proper conditional block, surrounded by
curly brackets.

The second one would be harder to replace because the loop contains two
`continue`s. Therefore, the second one is marked as intentional by
casting the value-to-discard to `void`.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Acked-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/compat/regex/regex_internal.c b/compat/regex/regex_internal.c
index ec5cc5d2dd..4a4f849629 100644
--- a/compat/regex/regex_internal.c
+++ b/compat/regex/regex_internal.c
@@ -1232,7 +1232,10 @@ re_node_set_merge (re_node_set *dest, const re_node_set *src)
        is = src->nelem - 1, id = dest->nelem - 1; is >= 0 && id >= 0; )
     {
       if (dest->elems[id] == src->elems[is])
-	is--, id--;
+	{
+	  is--;
+	  id--;
+	}
       else if (dest->elems[id] < src->elems[is])
 	dest->elems[--sbase] = src->elems[is--];
       else /* if (dest->elems[id] > src->elems[is]) */