[PATCH] completion: matcher correspondence classes: fix offset

[m0viefreak <m0viefreak.cm@googlemail.com>]

The "compfiles" function passes the matcher through the
"cfp_matcher_range" function to turn a prefix into
character classes. Example:

  matcher: m:{a-z}={A-Z}
  prefix: fo<tab>
  file list: foo1.txt FOO2.txt

the cfp_matcher_range function is supposed to turn the
prefix into:

  [fF][oO]

However there is bug which causes the offset to shift
by 1. Without this patch it returns:

  [fE][oN]

The bug was unnoticed before, because in the usual
case -- that is when matcher-list is set -- _path_files
calls compfiles -p ... "m:{a-z}={A-Z} m:{a-z}={A-Z}"
with the matcher added twice. This causes
"cfp_matcher_range" to do nothing at all, and instead
the whole list of files in the directory is returned.
Then it is filtered using compadd -D.

A case where this bug surfaces is the following:

Make sure no global matcher-list is set and set a single
matcher instead:

  zstyle -d ':completion:*' matcher-list
  zstyle ':completion:*' matcher 'm:{a-z}={A-Z}'

Now the completion

  cat fo<tab>

only offers "foo1.txt" but not "FOO2.txt".

Questions I couldn't anwswer, yet:
a) Why does "cfp_matcher_range" do nothing if more than
   one matcher spec is given?
b) Do we even need the "cfp_matcher_range" function
   at all? Seems like the later compadd -D works just
   fine and we could remove a whole bunch of unneeded
   functions that are only called from cfp_matcher_range.
c) Why does _path_files duplicate all matcher-list
   entries when calling "compfiles -p"?
---
 Src/Zle/compmatch.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Src/Zle/compmatch.c b/Src/Zle/compmatch.c
index 0e41ac3..667d71d 100644
--- a/Src/Zle/compmatch.c
+++ b/Src/Zle/compmatch.c
@@ -1218,7 +1218,7 @@ pattern_match_equivalence(Cpattern lp, convchar_t wind, int wmtp,
     convchar_t lchr;
     int lmtp;
 
-    if (!PATMATCHINDEX(lp->u.str, wind-1, &lchr, &lmtp)) {
+    if (!PATMATCHINDEX(lp->u.str, wind, &lchr, &lmtp)) {
 	/*
 	 * No equivalent.  No possible match; give up.
 	 */
-- 
2.5.0.234.gefc8a62