0005322: Problem with forall and method

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Date Submitted

Last Update

0005322

OCaml

OCaml general

public

2011-07-28 11:18

2011-07-29 03:56

Reporter

poluxmoon

Assigned To

Priority

normal

Severity

minor

Reproducibility

always

Status

closed

Resolution

fixed

Platform

OS Version

Product Version

3.12.0

Target Version

Fixed in Version

3.13.0+dev

Summary

0005322: Problem with forall and method

Description

Type error on code similar to :

-----
type 'par t = 'par

let ident v = v

class alias =
object
  method alias : 'a . 'a t -> 'a = ident (* type error here *)
end
-----

Which gives :

-----
Error: This expression has type 'a. 'a t -> 'a
       but an expression was expected of type 'b. 'b t -> 'b
       Type 'a a = 'a is not compatible with type 'b t = 'b
-----

Additional Information

The problem is related to unification of foralls containing named type in a method.
The compiler accepts equivalent code when not using the named type "t" or when not using a method (see attached file).

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No tags attached.

Attached Files

forallclass.ml [^] (300 bytes) 2011-07-28 11:18

Relationships

Notes
(0006066) garrigue (manager) 2011-07-29 03:56	Thanks for your report. Both Ctype.unify3 and Ctype.moregen didn't consider the possibility that a type abbreviation may expand to a universal type variable. This is now fixed in both trunk and 3.12 branch (revision 11159).

Issue History
Date Modified	Username	Field	Change
2011-07-28 11:18	poluxmoon	New Issue
2011-07-28 11:18	poluxmoon	File Added: forallclass.ml
2011-07-29 03:56	garrigue	Note Added: 0006066
2011-07-29 03:56	garrigue	Status	new => closed
2011-07-29 03:56	garrigue	Resolution	open => fixed
2011-07-29 03:56	garrigue	Fixed in Version	=> 3.13.0+dev