Use match variable in mappings to avoid unsed variables

Author: xguerin

bitstring.opam

@@ -1,6 +1,6 @@
 # This file is generated by dune, edit dune-project instead
 opam-version: "2.0"
-version: "5.0.1"
+version: "5.0.2"
 synopsis: "Bitstrings and bitstring matching for OCaml"
 description: """
 The ocaml-bitstring project adds Erlang-style bitstrings and matching over bitstrings as a syntax extension and library for OCaml. 

dune-project

@@ -2,7 +2,7 @@
 
 (name bitstring)
 
-(version 5.0.1)
+(version 5.0.2)
 
 (generate_opam_files true)
 
@@ -34,7 +34,7 @@
  )
  (depends
   (ocaml (>= 5.2.0))
-  (bitstring (>= 5.0.1))
+  (bitstring (>= 5.0.2))
   (ocaml (and :with-test (>= 5.2.0)))
   (ppxlib (>= 0.36.0))
   (ounit :with-test)))

ppx/ppx_bitstring.ml

@@ -18,6 +18,12 @@ open Ppxlib
 open Printf
 open Ast_builder.Default
 
+(* Exception *)
+
+let location_exn ~loc msg =
+  Location.raise_errorf ~loc "%s" msg
+;;
+
 (* Type definition *)
 
 module Entity = struct
@@ -167,13 +173,12 @@ module MatchField = struct
     | Any of Parsetree.pattern
     | Tuple of tuple
   ;;
-end
 
-(* Exception *)
-
-let location_exn ~loc msg =
-  Location.raise_errorf ~loc "%s" msg
-;;
+  let as_evar v = 
+    match v.pat with
+    | {ppat_desc = Ppat_var(v); _} -> evar ~loc:v.loc v.txt
+    | {ppat_loc; _} -> location_exn ~loc:ppat_loc "Pattern is not a variable"
+end
 
 (* Helper functions *)
 
@@ -691,7 +696,8 @@ let gen_value ~loc fld res beh =
   | Some b, None  ->
     [%expr let [%p fld.pat] = [%e b] in [%e beh]][@metaloc loc]
   | None, Some m  ->
-    [%expr let [%p fld.pat] = [%e m] [%e res] in [%e beh]][@metaloc loc]
+    let exp = MatchField.as_evar fld in
+    [%expr let [%p fld.pat] = [%e m] [%e exp] in [%e beh]][@metaloc loc]
   | _, _ -> beh
 ;;
 

ppx_bitstring.opam

@@ -1,6 +1,6 @@
 # This file is generated by dune, edit dune-project instead
 opam-version: "2.0"
-version: "5.0.1"
+version: "5.0.2"
 synopsis: "Bitstrings and bitstring matching for OCaml - PPX extension"
 description: """
 The ocaml-bitstring project adds Erlang-style bitstrings and matching over bitstrings as a syntax extension and library for OCaml. 
@@ -15,7 +15,7 @@ bug-reports: "https://github.com/xguerin/bitstring/issues"
 depends: [
   "dune" {>= "2.7"}
   "ocaml" {>= "5.2.0"}
-  "bitstring" {>= "5.0.1"}
+  "bitstring" {>= "5.0.2"}
   "ocaml" {with-test & >= "5.2.0"}
   "ppxlib" {>= "0.36.0"}
   "ounit" {with-test}

tests/BitstringQualifierTest.ml

@@ -22,16 +22,18 @@ open Bitstring
  *)
 
 let map_test context =
-  let source = [%bitstring {| 1 : 16 ; 2 : 16 |}] in
+  let source = [%bitstring {| 1 : 16 ; 2 : 16 ; 0 : 16 |}] in
   match%bitstring source with
   | {| value0 : 16 : map (fun v -> v + 1)
      ; value1 : 16 : map (fun v -> Some v)
+     ; value2 : 16 : map (fun v -> match v with | 0 -> false | _ -> true) 
     |} ->
     assert_equal value0 2;
     begin match value1 with
       | Some v -> assert_equal v 2
       | _      -> assert_bool "Invalid map result" false
-    end
+    end;
+    assert_bool "Invalid boolean value" (not value2) 
   | {| _ |} -> assert_bool "Invalid pattern" false
 
 (*