regcomp.c: Add comment, Note for 3018b8238

This adds a comment for this code, which I mistakenly included in commit
3018b823898645e44b8c37c70ac5c6302b031381, and should have been in its
own commit.  The code optimizes something that has a quantifier of zero
into a NOTHING node.

diff --git a/regcomp.c b/regcomp.c
index 1a746ca..c28ea5e 100644 (file)
--- a/regcomp.c
+++ b/regcomp.c
@@ -9402,7 +9402,7 @@ S_regpiece(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth)
                 ret = reg_node(pRExC_state, OPFAIL);
                 return ret;
             }
-            else if (max == 0) {
+            else if (max == 0) {    /* replace {0} with a nothing node */
                 if (SIZE_ONLY) {
                     RExC_size = PREVOPER(RExC_size) - regarglen[(U8)NOTHING];
                 }