Better type propagation within object literals #7159
Description
Original bug ID: 7159
Reporter: @alainfrisch
Assigned to: @garrigue
Status: acknowledged (set by @garrigue on 2016-03-02T00:43:12Z)
Resolution: open
Priority: low
Severity: feature
Target version: undecided
Category: typing
Monitored by: @hcarty
Bug description
Compare:
# (("abc", 42) : (int * int));;
Characters 2-7:
(("abc", 42) : (int * int));;
^^^^^
Error: This expression has type string but an expression was expected of type
int
and
# (object method x = "abc" method y = 42 end : <x: int; y: int>);;
Characters 1-42:
(object method x = "abc" method y = 42 end : <x: int; y: int>);;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error: This expression has type < x : string; y : int >
but an expression was expected of type < x : int; y : int >
Types for method x are incompatible
It could be useful (for error messages and type-based selection) to propagate types from the context to the method bodies for an object literal.
In case of an immediate annotation on the object literal, one can already put the constraint on "this":
# object(_ : <x: int; y:int>) method x = "abc" method y = 42 end;;
Characters 39-44:
object(_ : <x: int; y:int>) method x = "abc" method y = 42 end;;
^^^^^
Error: This expression has type string but an expression was expected of type
int