From 21bcc5f6fc8db1ccad16dea89f1705a799c1d090 Mon Sep 17 00:00:00 2001
From: Hugo Herbelin
Date: Thu, 27 Dec 2018 08:56:23 +0100
Subject: Notations: Enforce strong evaluation of cases_pattern_of_glob_constr.

This is because it can raise Not_found in depth and we need to catch
it at the right time.
---
 interp/notation_ops.ml          |  5 +----
 lib/dAst.ml                     |  2 ++
 lib/dAst.mli                    |  1 +
 pretyping/glob_ops.ml           | 10 ++++++++--
 pretyping/glob_ops.mli          |  1 +
 test-suite/success/Notations2.v | 11 +++++++++++
 6 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/interp/notation_ops.ml b/interp/notation_ops.ml
index 890c24e633..7d7e10a05b 100644
--- a/interp/notation_ops.ml
+++ b/interp/notation_ops.ml
@@ -908,11 +908,8 @@ let bind_term_as_binding_env alp (terms,termlists,binders,binderlists as sigma)
     (* TODO: look at the consequences for alp *)
     alp, add_env alp sigma var (DAst.make @@ GVar id)
 
-let force_cases_pattern c =
-  DAst.make ?loc:c.CAst.loc (DAst.get c)
-
 let bind_binding_as_term_env alp (terms,termlists,binders,binderlists as sigma) var c =
-  let pat = try force_cases_pattern (cases_pattern_of_glob_constr Anonymous c) with Not_found -> raise No_match in
+  let pat = try cases_pattern_of_glob_constr Anonymous c with Not_found -> raise No_match in
   try
     (* If already bound to a binder, unify the term and the binder *)
     let patl' = Id.List.assoc var binders in
diff --git a/lib/dAst.ml b/lib/dAst.ml
index f34ab956a3..803b2a0cff 100644
--- a/lib/dAst.ml
+++ b/lib/dAst.ml
@@ -30,6 +30,8 @@ let make ?loc v = CAst.make ?loc (Value v)
 
 let delay ?loc v = CAst.make ?loc (Thunk (Lazy.from_fun v))
 
+let force x = CAst.make ?loc:x.CAst.loc (Value (get_thunk x.v))
+
 let map f n = CAst.map (fun x -> map_thunk f x) n
 
 let map_with_loc f n =
diff --git a/lib/dAst.mli b/lib/dAst.mli
index 28c78784e6..2f58cfc41f 100644
--- a/lib/dAst.mli
+++ b/lib/dAst.mli
@@ -21,6 +21,7 @@ val get_thunk : ('a, 'b) thunk -> 'a
 
 val make : ?loc:Loc.t -> 'a -> ('a, 'b) t
 val delay : ?loc:Loc.t -> (unit -> 'a) -> ('a, [ `thunk ]) t
+val force : ('a, 'b) t -> ('a, 'b) t
 
 val map : ('a -> 'b) -> ('a, 'c) t -> ('b, 'c) t
 val map_with_loc : (?loc:Loc.t -> 'a -> 'b) -> ('a, 'c) t -> ('b, 'c) t
diff --git a/pretyping/glob_ops.ml b/pretyping/glob_ops.ml
index 6b61b1452e..68626597fc 100644
--- a/pretyping/glob_ops.ml
+++ b/pretyping/glob_ops.ml
@@ -485,7 +485,11 @@ let is_gvar id c = match DAst.get c with
 | GVar id' -> Id.equal id id'
 | _ -> false
 
-let rec cases_pattern_of_glob_constr na = DAst.map (function
+let rec cases_pattern_of_glob_constr na c =
+  (* Forcing evaluation to ensure that the possible raising of
+     Not_found is not delayed *)
+  let c = DAst.force c in
+  DAst.map (function
   | GVar id ->
     begin match na with
     | Name _ ->
@@ -498,6 +502,8 @@ let rec cases_pattern_of_glob_constr na = DAst.map (function
   | GApp (c, l) ->
     begin match DAst.get c with
     | GRef (ConstructRef cstr,_) ->
+      let nparams = Inductiveops.inductive_nparams (fst cstr) in
+      let _,l = List.chop nparams l in
       PatCstr (cstr,List.map (cases_pattern_of_glob_constr Anonymous) l,na)
     | _ -> raise Not_found
     end
@@ -505,7 +511,7 @@ let rec cases_pattern_of_glob_constr na = DAst.map (function
      (* A canonical encoding of aliases *)
      DAst.get (cases_pattern_of_glob_constr na' b)
   | _ -> raise Not_found
-  )
+  ) c
 
 open Declarations
 open Term
diff --git a/pretyping/glob_ops.mli b/pretyping/glob_ops.mli
index 91a2ef9c1e..c189a3bcb2 100644
--- a/pretyping/glob_ops.mli
+++ b/pretyping/glob_ops.mli
@@ -89,6 +89,7 @@ val map_pattern : (glob_constr -> glob_constr) ->
 
 (** Conversion from glob_constr to cases pattern, if possible
 
+    Evaluation is forced.
     Take the current alias as parameter,
     @raise Not_found if translation is impossible *)
 val cases_pattern_of_glob_constr : Name.t -> 'a glob_constr_g -> 'a cases_pattern_g
diff --git a/test-suite/success/Notations2.v b/test-suite/success/Notations2.v
index 1b33863e3b..2533a39cc4 100644
--- a/test-suite/success/Notations2.v
+++ b/test-suite/success/Notations2.v
@@ -154,3 +154,14 @@ Module M16.
   Print Grammar foo.
   Print Grammar foo2.
 End M16.
+
+(* Example showing the need for strong evaluation of
+   cases_pattern_of_glob_constr (this used to raise Not_found at some
+   time) *)
+
+Module M17.
+
+Notation "# x ## t & u" := ((fun x => (x,t)),(fun x => (x,u))) (at level 0, x pattern).
+Check fun y : nat => # (x,z) ## y & y.
+
+End M17.
-- 
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