0004522: Camlp4 erases unused optional arguments

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Date Submitted

Last Update

0004522

OCaml

Camlp4

public

2008-03-19 20:48

2012-09-15 12:31

Reporter

mottl

Assigned To

Priority

normal

Severity

minor

Reproducibility

always

Status

closed

Resolution

fixed

Platform

OS Version

Product Version

3.10.1

Target Version

4.00.1+dev

Fixed in Version

3.12.0

Summary

0004522: Camlp4 erases unused optional arguments

Description

The following valid code cannot be compiled when preprocessed with Camlp4:

  module type S = sig val f : ?x : 'a -> unit -> unit end
  module M : S = struct let f ?x:_ () = () end

Compiler output (with ocamlc -pp camlp4o foo.ml):

  File "foo.ml", line 2, characters 15-44:
  Signature mismatch:
  Modules do not match: sig val f : 'a -> unit -> unit end is not included in S
  Values do not match:
    val f : 'a -> unit -> unit
  is not included in
    val f : ?x:'a -> unit -> unit

The label of the ignored optional argument obviously got deleted by Camlp4 as evidenced by the output when pretty-printing with "camlp4o -printer o foo.ml":

  module type S = sig val f : ?x: 'a -> unit -> unit end
  module M : S = struct let f _ () = () end

Regards,
Markus

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Notes
(0007945) mrm (reporter) 2012-08-15 21:02 edited on: 2012-08-15 21:09	The problem with optional arguments in the original syntax is fixed in OCaml 3.12 and was caused by: 1) An old bug in the camlp4 parsing engine (PR#4603, PR#4330,PR#4551, PR#4513) which was fixed by ertai in http://caml.inria.fr/cgi-bin/viewvc.cgi?view=revision&revision=9053 [^] 2) A bug in Camlp4OCamlParser.ml (PR#4939) which was fixed in http://caml.inria.fr/cgi-bin/viewvc.cgi?view=revision&revision=11034 [^] -- Max Mouratov

(0007973) hongboz (developer) 2012-08-22 14:17	Should this be closed? I can not reproduce it

(0008081) doligez (manager) 2012-09-15 12:31	As Max said, the problem is fixed since 3.12.0

Issue History
Date Modified	Username	Field	Change
2008-03-19 20:48	mottl	New Issue
2008-03-20 10:50	ertai	Status	new => assigned
2008-03-20 10:50	ertai	Assigned To	=> ertai
2012-07-11 15:53	doligez	Assigned To	ertai =>
2012-07-11 15:53	doligez	Status	assigned => acknowledged
2012-07-11 15:53	doligez	Target Version	=> 4.01.0+dev
2012-07-31 13:37	doligez	Target Version	4.01.0+dev => 4.00.1+dev
2012-08-15 21:02	mrm	Note Added: 0007945
2012-08-15 21:09	mrm	Note Edited: 0007945	View Revisions
2012-08-22 14:17	hongboz	Note Added: 0007973
2012-09-15 12:31	doligez	Note Added: 0008081
2012-09-15 12:31	doligez	Status	acknowledged => closed
2012-09-15 12:31	doligez	Resolution	open => fixed
2012-09-15 12:31	doligez	Fixed in Version	=> 3.12.0