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errortrace.ml
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errortrace.ml
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(**************************************************************************)
(* *)
(* OCaml *)
(* *)
(* Florian Angeletti, projet Cambium, Inria Paris *)
(* Antal Spector-Zabusky, Jane Street, New York *)
(* *)
(* Copyright 2018 Institut National de Recherche en Informatique et *)
(* en Automatique. *)
(* Copyright 2021 Jane Street Group LLC *)
(* *)
(* All rights reserved. This file is distributed under the terms of *)
(* the GNU Lesser General Public License version 2.1, with the *)
(* special exception on linking described in the file LICENSE. *)
(* *)
(**************************************************************************)
open Types
open Format_doc
type position = First | Second
let swap_position = function
| First -> Second
| Second -> First
let print_pos ppf = function
| First -> fprintf ppf "first"
| Second -> fprintf ppf "second"
type expanded_type = { ty: type_expr; expanded: type_expr }
let trivial_expansion ty = { ty; expanded = ty }
type 'a diff = { got: 'a; expected: 'a }
let map_diff f r =
(* ordering is often meaningful when dealing with type_expr *)
let got = f r.got in
let expected = f r.expected in
{ got; expected }
let swap_diff x = { got = x.expected; expected = x.got }
type 'a escape_kind =
| Constructor of Path.t
| Univ of type_expr
(* The type_expr argument of [Univ] is always a [Tunivar _],
we keep a [type_expr] to track renaming in {!Printtyp} *)
| Self
| Module_type of Path.t
| Equation of 'a
| Constraint
type 'a escape =
{ kind : 'a escape_kind;
context : type_expr option }
let map_escape f esc =
{esc with kind = match esc.kind with
| Equation eq -> Equation (f eq)
| (Constructor _ | Univ _ | Self | Module_type _ | Constraint) as c -> c}
let explain trace f =
let rec explain = function
| [] -> None
| [h] -> f ~prev:None h
| h :: (prev :: _ as rem) ->
match f ~prev:(Some prev) h with
| Some _ as m -> m
| None -> explain rem in
explain (List.rev trace)
(* Type indices *)
type unification = private Unification
type comparison = private Comparison
type fixed_row_case =
| Cannot_be_closed
| Cannot_add_tags of string list
type 'variety variant =
(* Common *)
| Incompatible_types_for : string -> _ variant
| No_tags : position * (Asttypes.label * row_field) list -> _ variant
(* Unification *)
| No_intersection : unification variant
| Fixed_row :
position * fixed_row_case * fixed_explanation -> unification variant
(* Equality & Moregen *)
| Presence_not_guaranteed_for : position * string -> comparison variant
| Openness : position (* Always [Second] for Moregen *) -> comparison variant
type 'variety obj =
(* Common *)
| Missing_field : position * string -> _ obj
| Abstract_row : position -> _ obj
(* Unification *)
| Self_cannot_be_closed : unification obj
type first_class_module =
| Package_cannot_scrape of Path.t
| Package_inclusion of Format_doc.doc
| Package_coercion of Format_doc.doc
type ('a, 'variety) elt =
(* Common *)
| Diff : 'a diff -> ('a, _) elt
| Variant : 'variety variant -> ('a, 'variety) elt
| Obj : 'variety obj -> ('a, 'variety) elt
| Escape : 'a escape -> ('a, _) elt
| Function_label_mismatch of Asttypes.arg_label diff
| Incompatible_fields : { name:string; diff: type_expr diff } -> ('a, _) elt
(* Could move [Incompatible_fields] into [obj] *)
| First_class_module: first_class_module -> ('a,_) elt
(* Unification & Moregen; included in Equality for simplicity *)
| Rec_occur : type_expr * type_expr -> ('a, _) elt
type ('a, 'variety) t = ('a, 'variety) elt list
type 'variety trace = (type_expr, 'variety) t
type 'variety error = (expanded_type, 'variety) t
let map_elt (type variety) f : ('a, variety) elt -> ('b, variety) elt = function
| Diff x -> Diff (map_diff f x)
| Escape {kind = Equation x; context} ->
Escape { kind = Equation (f x); context }
| Escape {kind = (Univ _ | Self | Constructor _ | Module_type _ | Constraint);
_}
| Variant _ | Obj _ | Function_label_mismatch _ | Incompatible_fields _
| Rec_occur (_, _) | First_class_module _ as x -> x
let map f t = List.map (map_elt f) t
let incompatible_fields ~name ~got ~expected =
Incompatible_fields { name; diff={got; expected} }
let swap_elt (type variety) : ('a, variety) elt -> ('a, variety) elt = function
| Diff x -> Diff (swap_diff x)
| Incompatible_fields { name; diff } ->
Incompatible_fields { name; diff = swap_diff diff}
| Obj (Missing_field(pos,s)) -> Obj (Missing_field(swap_position pos,s))
| Obj (Abstract_row pos) -> Obj (Abstract_row (swap_position pos))
| Variant (Fixed_row(pos,k,f)) ->
Variant (Fixed_row(swap_position pos,k,f))
| Variant (No_tags(pos,f)) ->
Variant (No_tags(swap_position pos,f))
| x -> x
let swap_trace e = List.map swap_elt e
type unification_error = { trace : unification error } [@@unboxed]
type equality_error =
{ trace : comparison error;
subst : (type_expr * type_expr) list }
type moregen_error = { trace : comparison error } [@@unboxed]
let unification_error ~trace : unification_error =
assert (trace <> []);
{ trace }
let equality_error ~trace ~subst : equality_error =
assert (trace <> []);
{ trace; subst }
let moregen_error ~trace : moregen_error =
assert (trace <> []);
{ trace }
type comparison_error =
| Equality_error of equality_error
| Moregen_error of moregen_error
let swap_unification_error ({trace} : unification_error) =
({trace = swap_trace trace} : unification_error)
module Subtype = struct
type 'a elt =
| Diff of 'a diff
type 'a t = 'a elt list
type trace = type_expr t
type error_trace = expanded_type t
type unification_error_trace = unification error (** To avoid shadowing *)
type nonrec error =
{ trace : error_trace
; unification_trace : unification error }
let error ~trace ~unification_trace =
assert (trace <> []);
{ trace; unification_trace }
let map_elt f = function
| Diff x -> Diff (map_diff f x)
let map f t = List.map (map_elt f) t
end