Original bug ID: 5344
Reporter: @lpw25
Assigned to: @xclerc
Status: closed (set by @xavierleroy on 2012-09-25T18:06:17Z)
Resolution: fixed
Priority: normal
Severity: minor
Version: 3.12.1
Fixed in version: 3.12.1+dev
Category: ~DO NOT USE (was: OCaml general)
Monitored by: @lpw25

Bug description

Fatal exceptions are sometimes printed in an unexpected way.

For example compiling the following:

type test = A of int * string
| B of int * string

exception TestExc of test

let _ = raise (TestExc (A(3, "HelloWorld")))

and running it produces:

bash-3.2$ ocamlc testA.ml
bash-3.2$ ocamlrun a.out
Fatal error: exception TestA.TestExc(3, "HelloWorld")

Whereas this program:

type test = A of int * string
| B of int * string

exception TestExc of test

let _ = raise (TestExc(B(3, "HelloWorld")))

produces this:

bash-3.2$ ocamlc testB.ml
bash-3.2$ ocamlrun a.out
Fatal error: exception TestB.TestExc(_)

The second example is probably the correct behaviour. The problem seems to be caused by lines 60-66 in caml_format_exception in byterun/printexc.c, which are supposed to handle printing exceptions like Match_Failure and Assert_Failure.