0005186: Exception aliasing does not preserve abstraction

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0005186

OCaml

OCaml general

public

2010-12-01 16:33

2012-09-19 14:26

Reporter

Julien Signoles

Assigned To

Priority

normal

Severity

minor

Reproducibility

always

Status

confirmed

Resolution

open

Platform

OS Version

Product Version

3.11.2

Target Version

4.01.0+dev

Fixed in Version

Summary

0005186: Exception aliasing does not preserve abstraction

Description

Hello,

Consider the following program:
==========
exception A
let f () = raise A
module M : sig exception B end = struct exception B = A end

let () =
  try f ()
  with
  | M.B -> Format.printf "M.B@."
  | A -> Format.printf "A@."
==========

The output is "M.B" since M.B matches before A. That is consistent with the dynamic semantics of exception aliasing and pattern matching (as far as I understand it) BUT it does not preserve abstraction since the interface of M does not say that M.B is an alias for A. Thus an external user of M cannot expect this behavior.

Sadly, I see no way to circumvent this issue (except to add a textual documentation to the interface of M) :-(.

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Notes
(0008114) doligez (manager) 2012-09-19 14:26	I'm not sure this should be considered a bug. Note that the interface of M does not say that M.B is NOT an alias for A, so maybe you shouldn't be surprised when it is.

Issue History
Date Modified	Username	Field	Change
2010-12-01 16:33	Julien Signoles	New Issue
2011-05-17 20:22	doligez	Status	new => acknowledged
2012-07-10 17:29	doligez	Target Version	=> 4.01.0+dev
2012-07-31 13:36	doligez	Target Version	4.01.0+dev => 4.00.1+dev
2012-09-19 14:26	doligez	Note Added: 0008114
2012-09-19 14:26	doligez	Status	acknowledged => confirmed
2012-09-19 14:26	doligez	Target Version	4.00.1+dev => 4.01.0+dev