Original bug ID: 6980
Reporter: @lpw25
Assigned to: @garrigue
Status: closed (set by @xavierleroy on 2017-02-16T14:16:28Z)
Resolution: fixed
Priority: normal
Severity: crash
Version: 4.02.2
Target version: 4.03.0+dev / +beta1
Fixed in version: 4.03.0+dev / +beta1
Category: typing
Monitored by: @diml @hcarty

Bug description

The following produces an assertion failure from ctype.ml:

type 'a t = [< Foo | Bar] as 'a;;

type 'a t = 'a constraint 'a = [< Bar | Foo ]

type 'a s = [< Foo | Bar | Baz > Bar] as 'a;;

type 'a s = 'a constraint 'a = [< Bar | Baz | Foo > Bar ]

type 'a first = First : 'a second -> ('b t as 'a) first

and 'a second = Second : ('b s as 'a) second;;

type 'a first = First : 'b t second -> ([< Bar | Foo ] as 'b) t first
and 'a second = Second : [< Bar | Baz | Foo > Bar ] s second

type aux = Aux : 'a t second * ('a -> int) -> aux;;

type aux = Aux : ([< Bar | Foo ] as 'a) t second * ('a -> int) -> aux

let it : 'a. [< Bar | Foo > Bar ] as 'a = Bar;;

val it : [< Bar | Foo > Bar ] = Bar

let g (Aux(Second, f)) = f it;;

Fatal error: exception File "typing/ctype.ml", line 1170, characters 8-14:
Assertion failed

Process ocaml-toplevel exited abnormally with code 2