patch for regex bug: (x|x){n}

On Mon, 16 Dec 1996 18:04:08 EST, I wrote:
>
>7.  Symmetry confounds quantified regex alternation
>
>A well-researched bug report sent in by Charles Bailey:
>
>     Message-Id: <01IA10O8ZIB600219C@hmivax.humgen.upenn.edu>,
>     Subject: Regex bug: (x|x){n}
>
>Pity I didn't have time to take a closer look at that one.

Here's a patch for the problem reported in the reference above.

Simpler test cases:

  % perl -we '$_ = "atatttta"; print "|$1|$2|\n" if /((t|t){3})/;'

says "|t||" instead of instead of "|ttt|t|"; and

  % perl -we '$_ = "atatttta"; print "|$1|$2|\n" if /((t|t){3,})/;'

says "|t||" instead of instead of "|tttt|t|"; and

p5p-msgid: <199612210259.VAA10170@aatma.engin.umich.edu>

diff --git a/regexec.c b/regexec.c
index 292f960..bed5a99 100644 (file)
--- a/regexec.c
+++ b/regexec.c
@@ -891,7 +891,7 @@ char *prog;
 
                /* If degenerate scan matches "", assume scan done. */
 
-               if (locinput == cc->lastloc) {
+               if (locinput == cc->lastloc && n >= cc->min) {
                    regcc = cc->oldcc;
                    ln = regcc->cur;
                    if (regmatch(cc->next))