From 305524932db142351d1ed4a9520eb29a5f24fa7f Mon Sep 17 00:00:00 2001
From: Octachron <octa@polychoron.fr>
Date: Fri, 30 Jan 2015 17:50:21 +0200
Subject: [PATCH] Warnings for using .{} without opening Bigarray

The previous change to the index operator .{} (and friends) broke backward
source code compatibility with the previous version of Ocaml. Program using
these operators without opening the Bigarray module triggered an error.
To alleviate this problem, this patch adds a temporary hack to the type
checker to transform the corresponding errors in a warning.
---
 typing/typetexp.ml | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/typing/typetexp.ml b/typing/typetexp.ml
index 523d435..e7b99bc 100644
--- a/typing/typetexp.ml
+++ b/typing/typetexp.ml
@@ -239,10 +239,29 @@ let find_class env loc lid =
   check_deprecated loc decl.cty_attributes (Path.name path);
   r

+(* With the simplification of index operators, the expression a.{..} are no longer resolved to Bigarray.Array[n].[g|s]et.
+To ease the transition period, we catch the case where the index operators .{}/.{,}.. are not bound in the current scope and reintroduce the
+binding with a deprecation warning. *)
+let lookup_value_with_deprecated_indexop loc lid env   =
+let lookup_deprecated lid env =
+ match lid with
+  | Longident.Lident s ->  ( match s with
+    | ".{}" | ".{}<-" | ".{,}" | ".{,}<-" |  ".{,,}" | ".{,,}<-" |  ".{,..,}" | ".{,..,}<-"  ->
+     let lid' =  Longident.( Ldot( Lident "Bigarray" , s ) ) in
+     let r = Env.lookup_value lid' env in
+     Location.prerr_warning loc (Warnings.Deprecated (
+Printf.sprintf "possible use of ( %s ) as Bigarray.( %s ). To avoid this warning, open the Bigarray module. If you did not intend to use the bigarray index operator, this warning implies that the ( %s ) operator was unbound " s s s ));
+    r
+    | _ -> raise Not_found
+  )
+  | _ -> raise Not_found in
+  try Env.lookup_value lid env with
+    | Not_found -> lookup_deprecated lid env
+[@@ocaml.deprecated "Temporary hack to ease the introduction of the new index operators .{}/.{,}... "]
+
 let find_value env loc lid =
   let (path, decl) as r =
-    find_component Env.lookup_value (fun lid -> Unbound_value lid) env loc lid
-  in
+  find_component (lookup_value_with_deprecated_indexop loc) (fun lid -> Unbound_value lid) env loc lid in
   check_deprecated loc decl.val_attributes (Path.name path);
   r

--
2.2.2