From 89308bcf4eac2b4bd0cc91a67499ddb918a9a56b Mon Sep 17 00:00:00 2001
From: Galfour <gabriel.alfour@gmail.com>
Date: Wed, 8 May 2019 13:46:16 +0000
Subject: [PATCH] add better error message when parsing expressions

---
 src/ligo/parser/parser.ml | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/ligo/parser/parser.ml b/src/ligo/parser/parser.ml
index f3057c843..854029d33 100644
--- a/src/ligo/parser/parser.ml
+++ b/src/ligo/parser/parser.ml
@@ -96,7 +96,18 @@ let parse_expression (s:string) : AST_Raw.expr result =
               end_.pos_lnum (end_.pos_cnum - end_.pos_bol) in
           simple_error str
         )
-      | _ -> simple_error "unrecognized parse_ error"
+      | exn ->
+          let start = Lexing.lexeme_start_p lexbuf in
+          let end_ = Lexing.lexeme_end_p lexbuf in
+          let str = Format.sprintf
+              "Unrecognized error (%s) at \"%s\" from (%d, %d) to (%d, %d). In expression \"%s|%s\"\n"
+              (Printexc.to_string exn)
+              (Lexing.lexeme lexbuf)
+              start.pos_lnum (start.pos_cnum - start.pos_bol)
+              end_.pos_lnum (end_.pos_cnum - end_.pos_bol)
+              start.pos_fname s
+          in
+          simple_error str
     ) @@ (fun () ->
       let raw = Parser.interactive_expr read lexbuf in
       close () ;