A class with non-ASCII runes matches them: [éa-z] is taken as (é|[a-z]), a range up to 256 runes spelled out

mvzr's classes hold bytes, and it refused a multibyte member as a bad expression. Rewriting the class before compiling, as ^a|^b already is, needs no mvzr patch; runes that differ only in their last byte go as one alternative (\xc3[\xa0-\xbf] for [à-ÿ]) so a 256-rune range fits the 512-operation limit, which counts the pattern as rewritten. A wider range and [^é] are refused, naming why.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 6 insertions, 1 deletions

diff --git a/docs/fs.md b/docs/fs.md
index 8464768b..af64fded 100644
--- a/docs/fs.md
+++ b/docs/fs.md
@@ -733,7 +733,12 @@ unanchored branches (`^def|x`) is refused, `bad regular expression`, since
 mvzr keeps `^` only first. A pattern may be up to 512 of mvzr's operations,
 about 512 characters (mvzr's own is 64; pardes builds it with more); a
 longer one is refused, `bad regular expression: longer than mvzr's 512
-operations`. An expression is
+operations`. A class may hold non-ASCII runes (`[éa-z]`, `[à-ÿ]`): it is
+taken as an alternation of them (`(é|[a-z])`), a range of up to 256 runes
+spelled out, and the 512 counts the pattern as rewritten. A wider range
+(`a range of runes wider than 256 in [...] is not supported`) and a negated
+class with a non-ASCII rune (`[^é]`) are refused, since mvzr's classes hold
+bytes. An expression is
 evaluated from the current address, the range last written to `addr` (or
 left by the last `data` write, just past it), as acme evaluates it from
 `w->addr` (xfid.c:446): `.` is that address, not the selection (`dot` is