Show lexer error messages in ReasonLIGO

src/passes/1-parser/reasonligo.ml

@@ -9,6 +9,16 @@ module SyntaxError = Parser_reasonligo.SyntaxError
 
 module Errors = struct
 
+  let lexer_error (e: Lexer.error AST.reg) =
+    let title () = "lexer error" in
+    let message () = Lexer.error_to_string e.value in
+    let data = [
+      ("parser_loc",
+       fun () -> Format.asprintf "%a" Location.pp_lift @@ e.region
+      )
+    ] in
+    error ~data title message
+
   let wrong_function_arguments expr =
     let title () = "wrong function arguments" in
     let message () = "" in
@@ -65,7 +75,10 @@ let parse (parser: 'a parser) lexbuf =
         let start = Lexing.lexeme_start_p lexbuf in
         let end_ = Lexing.lexeme_end_p lexbuf in
         fail @@ (parser_error start end_)
+      | Lexer.Error e ->
+        fail @@ (lexer_error e)
       | _ ->
+        let _ = Printexc.print_backtrace Pervasives.stdout in
         let start = Lexing.lexeme_start_p lexbuf in
         let end_ = Lexing.lexeme_end_p lexbuf in
         fail @@ (unrecognized_error start end_)

src/passes/1-parser/shared/Lexer.mli

@@ -138,6 +138,8 @@ module type S =
 
     type error
 
+    val error_to_string : error -> string
+
     exception Error of error Region.reg
 
     val print_error :

src/passes/1-parser/shared/Lexer.mll

@@ -160,6 +160,9 @@ module type S = sig
   (* Error reporting *)
 
   type error
+  
+  val error_to_string : error -> string
+
   exception Error of error Region.reg
 
   val print_error : ?offsets:bool -> [`Byte | `Point] ->
@@ -345,7 +348,7 @@ module Make (Token: TOKEN) : (S with module Token = Token) =
     | Negative_byte_sequence
     | Broken_string
     | Invalid_character_in_string
-    | Reserved_name
+    | Reserved_name of string
     | Invalid_symbol
     | Invalid_natural
 
@@ -387,8 +390,8 @@ module Make (Token: TOKEN) : (S with module Token = Token) =
     | Invalid_character_in_string ->
         "Invalid character in string.\n\
          Hint: Remove or replace the character.\n"
-    | Reserved_name ->
-        "Reserved named.\n\
+    | Reserved_name s ->
+        "Reserved name: " ^ s ^ ".\n\
          Hint: Change the name.\n"
     | Invalid_symbol ->
         "Invalid symbol.\n\
@@ -486,7 +489,7 @@ module Make (Token: TOKEN) : (S with module Token = Token) =
       let region, lexeme, state = sync state buffer in
       match Token.mk_ident lexeme region with
         Ok token -> token, state
-      | Error Token.Reserved_name -> fail region Reserved_name
+      | Error Token.Reserved_name -> fail region (Reserved_name lexeme)
 
     let mk_constr state buffer =
       let region, lexeme, state = sync state buffer