* regex-posix.c (scm_regexp_exec): Reliably mark unmatched

subexpressions.  (Thanks to Charbel Jacquin.)

diff --git a/libguile/regex-posix.c b/libguile/regex-posix.c
index 0ac816c..9b1ec07 100644 (file)
--- a/libguile/regex-posix.c
+++ b/libguile/regex-posix.c
@@ -252,8 +252,12 @@ scm_regexp_exec (SCM rx, SCM str, SCM start, SCM flags)
       mvec = scm_make_vector (SCM_MAKINUM (nmatches + 1), SCM_UNSPECIFIED);
       SCM_VELTS(mvec)[0] = str;
       for (i = 0; i < nmatches; ++i)
-       SCM_VELTS(mvec)[i+1] = scm_cons(SCM_MAKINUM(matches[i].rm_so + offset),
-                                       SCM_MAKINUM(matches[i].rm_eo + offset));
+       if (matches[i].rm_so == -1)
+         SCM_VELTS(mvec)[i+1] = scm_cons (SCM_MAKINUM (-1), SCM_MAKINUM (-1));
+       else
+         SCM_VELTS(mvec)[i+1]
+           = scm_cons(SCM_MAKINUM(matches[i].rm_so + offset),
+                      SCM_MAKINUM(matches[i].rm_eo + offset));
     }
   scm_must_free ((char *) matches);
   SCM_ALLOW_INTS;