0004296: compilation failed on module types with duplicated values

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0004296

OCaml

OCaml general

public

2007-05-24 18:29

2010-04-30 06:42

Reporter

prevosto

Assigned To

Priority

normal

Severity

minor

Reproducibility

always

Status

closed

Resolution

fixed

Platform

OS Version

Product Version

3.10.0

Target Version

Fixed in Version

3.12.0+dev

Summary

0004296: compilation failed on module types with duplicated values

Description

--- test.ml
module type B = sig val x: int val y: int val x: int end
---
ocamlc -c test.ml
The implementation test.ml does not match the interface (inferred signature):
Module type declarations do not match:
module type B = sig val x : int val y : int val x : int end
does not match
module type B = sig val x : int val y : int val x : int end
Illegal permutation of structure fields

It seems like the duplicated fields are ordered differently when producing the interface and the bytecode. module type B above is quite silly, but the same thing happens of course when the duplication comes from included modules, in which case it is not possible to simply erase one of the fields in the source, such as in the example below:

--- test2.ml
module type A = sig val x: int val y: int end
module type B = sig val x: int val z: int end
module type C = sig include A include B end
---

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duplicate of

0004136

closed

Obscure compilation message error "Illegal permutation of structure fields"

Notes
(0004071) ertai (developer) 2007-05-25 11:03	The error message is not ideal but the problem is that your signature is not satisfiable, so you should fix it.

(0004074) prevosto (reporter) 2007-05-25 14:45	According to the compiler, the signature is perfectly satisfiable. At least in the sense that you can use it as the signature of a module implementation: module A: sig val x: int val y: int val x:int end = struct let x = 0 let y = 1 end is accepted by the compiler (and of course you can remove the sig from the .ml to put it in the .mli

(0005421) garrigue (manager) 2010-04-30 06:42	Fixed together with the introduction of destructive substitution (revision 10263).

Issue History
Date Modified	Username	Field	Change
2007-05-24 18:29	prevosto	New Issue
2007-05-25 11:03	ertai	Note Added: 0004071
2007-05-25 14:45	prevosto	Note Added: 0004074
2007-11-10 15:27	xleroy	Status	new => acknowledged
2009-08-25 15:19	xclerc	Relationship added	duplicate of 0004136
2010-04-30 06:42	garrigue	Note Added: 0005421
2010-04-30 06:42	garrigue	Status	acknowledged => closed
2010-04-30 06:42	garrigue	Resolution	open => fixed
2010-04-30 06:42	garrigue	Fixed in Version	=> 3.12.0+dev