Resolving record fields using all specified fields #5525
Description
Original bug ID: 5525
Reporter: @alainfrisch
Assigned to: @garrigue
Status: closed (set by @xavierleroy on 2015-12-11T18:25:43Z)
Resolution: fixed
Priority: normal
Severity: feature
Fixed in version: 4.01.0+dev
Category: typing
Related to: #4172 #5528
Child of: #5759
Monitored by: @gasche tgazagna @diml pveber @ygrek @hcarty
Bug description
With punning on record labels, programmers have a stronger incentive to use nice short names for record labels and avoid the disambiguation-by-prefixing technique.
The following proposal would make it possible, in some cases, to work with several record types that share some field names: when typing a record literal {[e0 with] l1 = e1; ... ; ln = en} or a record pattern {l1 = p1; ...; ln = pn}, the type-checker would search the current typing environment for a record type declaration that includes all the fields {l1, ..., ln}.
This cannot break existing well-typed code.
We have been using this modified resolution at LexiFi for a few years now. The patch is tiny. I can adapt it to the OCaml trunk if the proposal is accepted.