Fix uncaught error and formatting bug

src/mlang/test_framework/irj_file.ml

@@ -86,7 +86,12 @@ let fail text buffer (checkpoint : _ Irj_parser.MenhirInterpreter.checkpoint) =
     (mk_position (MenhirLib.ErrorReports.last buffer))
 
 let parse_file (test_name : string) : Irj_ast.irj_file =
-  let text, filebuf = MenhirLib.LexerUtil.read test_name in
+  let text, filebuf =
+    try MenhirLib.LexerUtil.read test_name
+    with Sys_error msg ->
+      Errors.raise_error
+        (Format.asprintf "Unable to open file %s (%s)" test_name msg)
+  in
   let supplier =
     Irj_parser.MenhirInterpreter.lexer_lexbuf_to_supplier Irj_lexer.token
       filebuf

src/mlang/utils/errors.ml

@@ -33,16 +33,18 @@ let format_structured_error fmt
 
 let format_structured_error_gnu_format fmt
     ((msg, pos) : string * (string option * Pos.t) list) =
-  Format.pp_print_list
-    ~pp_sep:(fun fmt () -> Format.pp_print_newline fmt ())
-    (fun fmt (pos_msg, pos) ->
-      Format.fprintf fmt "%a: %s %a\n" Pos.format_position_gnu pos msg
-        (fun fmt pos_msg ->
-          match pos_msg with
-          | None -> ()
-          | Some pos_msg -> Format.fprintf fmt "[%s]" pos_msg)
-        pos_msg)
-    fmt pos
+  if pos = [] then Format.fprintf fmt "%s\n" msg
+  else
+    Format.pp_print_list
+      ~pp_sep:(fun fmt () -> Format.pp_print_newline fmt ())
+      (fun fmt (pos_msg, pos) ->
+        Format.fprintf fmt "%a: %s %a\n" Pos.format_position_gnu pos msg
+          (fun fmt pos_msg ->
+            match pos_msg with
+            | None -> ()
+            | Some pos_msg -> Format.fprintf fmt "[%s]" pos_msg)
+          pos_msg)
+      fmt pos
 
 let raise_spanned_error (msg : string) ?(span_msg : string option)
     (span : Pos.t) : 'a =

src/mlang/utils/pos.ml

@@ -177,26 +177,31 @@ let retrieve_loc_text (pos : t) : string =
     let print_matched_line (line : string) (line_no : int) : string =
       let line_indent = indent_number line in
       let error_indicator_style = [ ANSITerminal.red; ANSITerminal.Bold ] in
+      let line_start_col =
+        if line_no = sline then get_start_column pos else 1
+      in
+      let line_end_col =
+        if line_no = eline then get_end_column pos else String.length line + 1
+      in
+      let line_length = String.length line + 1 in
       line
       ^
       if line_no >= sline && line_no <= eline then
         "\n"
         ^
         if line_no = sline && line_no = eline then
-          Cli.format_with_style error_indicator_style "%*s"
-            (get_end_column pos - 1)
-            (String.make (get_end_column pos - get_start_column pos) '^')
+          Cli.format_with_style error_indicator_style "%*s" (line_end_col - 1)
+            (String.make (line_end_col - line_start_col) '^')
         else if line_no = sline && line_no <> eline then
-          Cli.format_with_style error_indicator_style "%*s"
-            (String.length line - 1)
-            (String.make (String.length line - get_start_column pos) '^')
+          Cli.format_with_style error_indicator_style "%*s" (line_length - 1)
+            (String.make (line_length - line_start_col) '^')
         else if line_no <> sline && line_no <> eline then
           Cli.format_with_style error_indicator_style "%*s%s" line_indent ""
-            (String.make (String.length line - line_indent) '^')
+            (String.make (line_length - line_indent) '^')
         else if line_no <> sline && line_no = eline then
           Cli.format_with_style error_indicator_style "%*s%*s" line_indent ""
-            (get_end_column pos - 1 - line_indent)
-            (String.make (get_end_column pos - line_indent) '^')
+            (line_end_col - 1 - line_indent)
+            (String.make (line_end_col - line_indent) '^')
         else assert false (* should not happen *)
       else ""
     in