Original bug ID: 6327
Reporter: @dbuenzli
Status: acknowledged (set by @mshinwell on 2014-05-30T11:46:11Z)
Resolution: open
Priority: low
Severity: tweak
Version: 4.01.0
Target version: later
Category: lexing and parsing
Tags: patch
Related to: #4627 #6961

Bug description

AFAIR my OCaml syntax this program should be rejected. It is accepted and running it (osx) results in an infinite loop.

cat t.ml

let () =
let rec loop n = match n with
| 0 -> ()
| n -> (); ; loop (n - 1)
in
loop 3

ocamlbuild t.native
Finished, 4 targets (0 cached) in 00:00:00.
time ./t.native
^C

real 0m15.264s
user 0m15.260s
sys 0m0.003s

Something must be wrong in the parsing of match branches as for example the following program is rightly rejected

cat t2.ml

let () =
let rec loop n =
if n = 0 then () else
((); ; loop (n - 1))
in
loop 3

ocamlbuild t2.native

• /Users/dbuenzli/.opam/4.01.0/bin/ocamldep.opt -modules t2.ml > t2.ml.depends
  File "t2.ml", line 5, characters 9-10:
  Error: Syntax error: ')' expected
  File "t2.ml", line 5, characters 4-5:
  Error: This '(' might be unmatched
  Command exited with code 2.
  Compilation unsuccessful after building 1 target (0 cached) in 00:00:00.

Thanks,

Daniel

File attachments

• 0001-forbid-match-as-first-element-of-a-sequence.patch