Original bug ID: 7702
Reporter: chengsun
Assigned to: @gasche
Status: resolved (set by @gasche on 2018-01-11T10:33:51Z)
Resolution: fixed
Priority: normal
Severity: crash
Version: 4.06.0
Fixed in version: 4.07.0+dev/beta2/rc1/rc2
Category: back end (clambda to assembly)
Monitored by: chengsun @nojb @hhugo @gasche @yakobowski

Bug description

The attached code miscompiles (on 4.03.0 through trunk, no flambda) due to cross-module inlining.

The cmm generated for b.ml looks incorrect. As far as I can tell, an ID is generated for a catch lambda using next_raise_count, but this ID is already used in the clambda inlined from a.ml.

a.ml:

let _unused _ = try () with _ -> ()

let trigger_bug x =
let ok =
match x with
| None
| Some "" -> true
| Some _ -> false
in
if x = Some "" && not ok then
failwith "impossible"
[@@inline always]

b.ml:

let bug x = A.trigger_bug x

c.ml:

let () =
B.bug (Some "");
Printf.printf "Bug failed to trigger :(\n

Steps to reproduce

$ tar xzf bug.tar.gz
$ ./compile.sh
$ ./a.out
Fatal error: exception Failure("impossible")

File attachments

• bug.tar.gz