Shocking four-year-old bug in collect/coll.

This originates to a commit on 2011-10-21. In that commit, I
attempted to make until/last clauses have visibility to the
bindings in the collect body (even though those are
discarded). The problem is that the until/last clause is tried
whether or not the body succeeds. When the body fails, no
bindings emanate from it. In that case, the until/last clause
is wrongly evaluated in an environment with no bindings
whatsoever, meaning that even bindings that existed before the
collect are not available to it.

* match.c (h_coll, v_collect): Evaluate the last/until clause
using the collect body bindings only if those bindings are not
nil, otherwise use the original bindings from before entry
into the collect.

1 files changed, 7 insertions, 2 deletions

diff --git a/match.c b/match.c
index 2995aca6..d2c2ef6e 100644
--- a/match.c
+++ b/match.c
@@ -862,9 +862,12 @@ static val h_coll(match_line_ctx *c)
                 match_line(ml_specline(*c, coll_specline)));
 
       if (until_last_specline) {
+        uses_or2;
         cons_bind (sym, spec, until_last_specline);
         cons_bind (until_last_bindings, until_pos,
-                   match_line(ml_bindings_specline(*c, new_bindings, spec)));
+                   match_line(ml_bindings_specline(*c,
+                                                   or2(new_bindings, c->bindings),
+                                                   spec)));
 
         if (until_pos) {
           until_pos = minus(until_pos, c->base);
@@ -2820,9 +2823,11 @@ static val v_collect(match_files_ctx *c)
       /* Until/last clause sees un-collated bindings from collect. */
       if (until_last_spec)
       {
+        uses_or2;
         cons_bind (sym, ul_spec, until_last_spec);
         cons_bind (until_last_bindings, success,
-                   match_files(mf_spec_bindings(*c, ul_spec, new_bindings)));
+                   match_files(mf_spec_bindings(*c, ul_spec,
+                                                or2(new_bindings, c->bindings))));
 
         if (success) {
           debuglf(specline, lit("until/last matched ~a:~d"),