fix the location of section-mismatch error positions

Author: gasche

bin/test/errors/parsing-errors.t

@@ -96,7 +96,7 @@ Mismatch between section-start and section-end:
   $ echo "{{#foo}} {{.}} {{/bar}}" > $PROBLEM
   $ mustache foo.json $PROBLEM
   Template parse error:
-  File "foo-bar.mustache", lines 1-2, characters 23-0:
+  File "foo-bar.mustache", line 1, characters 0-23:
   Section mismatch: {{#foo}} is closed by {{/bar}}.
   [3]
 
@@ -111,7 +111,7 @@ Mismatch between section-start and section-end:
   $ echo "{{#bar}} {{#foo}} {{.}} {{/bar}} {{/foo}}" > $PROBLEM
   $ mustache foo.json $PROBLEM
   Template parse error:
-  File "wrong-nesting.mustache", lines 1-2, characters 41-0:
+  File "wrong-nesting.mustache", line 1, characters 9-32:
   Section mismatch: {{#foo}} is closed by {{/bar}}.
   [3]
 

lib/mustache.ml

@@ -157,10 +157,10 @@ and template_parse_error_kind =
 exception Template_parse_error of template_parse_error
 
 let parse_lx (lexbuf: Lexing.lexbuf) : Locs.t =
-  let raise_err lexbuf kind =
-    let loc =
-      let open Lexing in
-      { loc_start = lexbuf.lex_start_p; loc_end = lexbuf.lex_curr_p } in
+  let loc_of lexbuf =
+    let open Lexing in
+    { loc_start = lexbuf.lex_start_p; loc_end = lexbuf.lex_curr_p } in
+  let raise_err loc kind =
     raise (Template_parse_error { loc; kind })
   in
   try
@@ -169,11 +169,11 @@ let parse_lx (lexbuf: Lexing.lexbuf) : Locs.t =
       Mustache_lexer.(handle_standalone mustache lexbuf)
   with
   | Mustache_lexer.Error msg ->
-    raise_err lexbuf (Lexing msg)
+    raise_err (loc_of lexbuf) (Lexing msg)
   | Mustache_parser.Error ->
-    raise_err lexbuf Parsing
-  | Mismatched_section { start_name; end_name } ->
-    raise_err lexbuf (Mismatched_section { start_name; end_name })
+    raise_err (loc_of lexbuf) Parsing
+  | Mismatched_section { loc; start_name; end_name } ->
+    raise_err loc (Mismatched_section { start_name; end_name })
 
 let of_string s = parse_lx (Lexing.from_string s)
 

lib/mustache_parser.mly

@@ -24,16 +24,17 @@
   open Mustache_types
   open Mustache_types.Locs
 
-  let parse_section start_name end_name contents =
+  let mkloc (start_pos, end_pos) =
+    { loc_start = start_pos;
+      loc_end = end_pos }
+
+  let parse_section loc start_name end_name contents =
     if start_name <> end_name then
-      raise (Mismatched_section { start_name; end_name });
+      raise (Mismatched_section { loc = mkloc loc; start_name; end_name });
     { contents; name = start_name }
 
-  let with_loc (startpos, endpos) desc =
-    let loc =
-      { loc_start = startpos;
-        loc_end = endpos } in
-    { loc; desc }
+  let with_loc loc desc =
+    { loc = mkloc loc; desc }
 %}
 
 %token EOF
@@ -57,13 +58,13 @@ section:
     e = mustache_expr
     se = CLOSE_SECTION {
     with_loc $sloc
-      (Inverted_section (parse_section ss se e))
+      (Inverted_section (parse_section $sloc ss se e))
   }
   | ss = OPEN_SECTION
     e = mustache_expr
     se = CLOSE_SECTION {
     with_loc $sloc
-      (Section (parse_section ss se e))
+      (Section (parse_section $sloc ss se e))
   }
 
 mustache_element:

lib/mustache_types.ml

@@ -85,6 +85,7 @@ end
 (* this exception is used internally in the parser,
    never exposed to users *)
 exception Mismatched_section of {
+  loc: loc;
   start_name: dotted_name;
   end_name: dotted_name;
 }