Merge PR #7941: Extend QuestionMark to produce a better error message in case of missing record field

4 files changed, 69 insertions, 3 deletions

diff --git a/engine/evar_kinds.ml b/engine/evar_kinds.ml
index 12e2fda8e2..ea1e572548 100644
--- a/engine/evar_kinds.ml
+++ b/engine/evar_kinds.ml
@@ -21,12 +21,27 @@ type matching_var_kind = FirstOrderPatVar of Id.t | SecondOrderPatVar of Id.t
 
 type subevar_kind = Domain | Codomain | Body
 
+(* maybe this should be a Projection.t *)
+type record_field = { fieldname : Constant.t; recordname : Names.inductive }
+
+type question_mark = {
+     qm_obligation: obligation_definition_status;
+     qm_name: Name.t;
+     qm_record_field: record_field option;
+}
+
+let default_question_mark = {
+  qm_obligation=Define true;
+  qm_name=Anonymous;
+  qm_record_field=None;
+}
+
 type t =
   | ImplicitArg of GlobRef.t * (int * Id.t option)
      * bool (** Force inference *)
   | BinderType of Name.t
   | NamedHole of Id.t (* coming from some ?[id] syntax *)
-  | QuestionMark of obligation_definition_status * Name.t
+  | QuestionMark of question_mark
   | CasesType of bool (* true = a subterm of the type *)
   | InternalHole
   | TomatchTypeParameter of inductive * int
diff --git a/engine/evar_kinds.mli b/engine/evar_kinds.mli
new file mode 100644
index 0000000000..4facdb2005
--- /dev/null
+++ b/engine/evar_kinds.mli
@@ -0,0 +1,51 @@
+(************************************************************************)
+(*         *   The Coq Proof Assistant / The Coq Development Team       *)
+(*  v      *   INRIA, CNRS and contributors - Copyright 1999-2018       *)
+(* <O___,, *       (see CREDITS file for the list of authors)           *)
+(*   \VV/  **************************************************************)
+(*    //   *    This file is distributed under the terms of the         *)
+(*         *     GNU Lesser General Public License Version 2.1          *)
+(*         *     (see LICENSE file for the text of the license)         *)
+(************************************************************************)
+
+open Names
+
+(** The kinds of existential variable *)
+
+(** Should the obligation be defined (opaque or transparent (default)) or
+    defined transparent and expanded in the term? *)
+
+type obligation_definition_status = Define of bool | Expand
+
+type matching_var_kind = FirstOrderPatVar of Id.t | SecondOrderPatVar of Id.t
+
+type subevar_kind = Domain | Codomain | Body
+
+(* maybe this should be a Projection.t *)
+(* Represents missing record field *)
+type record_field = { fieldname : Constant.t; recordname : Names.inductive }
+
+type question_mark = {
+     qm_obligation: obligation_definition_status;
+     qm_name: Name.t;
+     (* Tracks if the evar represents a missing record field *)
+     qm_record_field: record_field option;
+}
+
+(* Default value of question_mark which is used most often *)
+val default_question_mark : question_mark
+
+type t =
+  | ImplicitArg of GlobRef.t * (int * Id.t option)
+     * bool (** Force inference *)
+  | BinderType of Name.t
+  | NamedHole of Id.t (* coming from some ?[id] syntax *)
+  | QuestionMark of question_mark
+  | CasesType of bool (* true = a subterm of the type *)
+  | InternalHole
+  | TomatchTypeParameter of inductive * int
+  | GoalEvar
+  | ImpossibleCase
+  | MatchingVar of matching_var_kind
+  | VarInstance of Id.t
+  | SubEvar of subevar_kind option * Evar.t
diff --git a/engine/proofview.ml b/engine/proofview.ml
index b4afb6415e..12d31e5f46 100644
--- a/engine/proofview.ml
+++ b/engine/proofview.ml
@@ -754,7 +754,7 @@ let mark_in_evm ~goal evd content =
                - GoalEvar (morally not dependent)
                - VarInstance (morally dependent of some name).
                This is a heuristic for naming these evars. *)
-            | loc, (Evar_kinds.QuestionMark (_,Names.Name id) |
+  | loc, (Evar_kinds.QuestionMark { Evar_kinds.qm_name=Names.Name id} |
                     Evar_kinds.ImplicitArg (_,(_,Some id),_)) -> loc, Evar_kinds.VarInstance id
             | _, (Evar_kinds.VarInstance _ | Evar_kinds.GoalEvar) as x -> x
             | loc,_ -> loc,Evar_kinds.GoalEvar }
diff --git a/engine/termops.ml b/engine/termops.ml
index 2b179c43b6..e4c8ae66bc 100644
--- a/engine/termops.ml
+++ b/engine/termops.ml
@@ -114,7 +114,7 @@ let pr_evar_suggested_name evk sigma =
   | None -> match evi.evar_source with
   | _,Evar_kinds.ImplicitArg (c,(n,Some id),b) -> id
   | _,Evar_kinds.VarInstance id -> id
-  | _,Evar_kinds.QuestionMark (_,Name id) -> id
+  | _,Evar_kinds.QuestionMark {Evar_kinds.qm_name = Name id} -> id
   | _,Evar_kinds.GoalEvar -> Id.of_string "Goal"
   | _ ->
       let env = reset_with_named_context evi.evar_hyps (Global.env()) in