[parser] use the loc of the prev sentence to feed the parser

In this way the line number in the loc is not reset to 0.
This has no use internally, since the document holds the text and
computes line number correctly, but Coq code and plugins may want
to display a loc (with a correct line number)

language-server/dm/document.ml

@@ -290,18 +290,18 @@ let parse_one_sentence stream ~st =
 
 
 [%%if coq = "8.18" || coq = "8.19"]
-let parse_one_sentence stream ~st =
+let parse_one_sentence ?loc stream ~st =
   Vernacstate.Synterp.unfreeze st;
   let entry = Pvernac.main_entry (Some (Synterp.get_default_proof_mode ())) in
-  let pa = Pcoq.Parsable.make stream in
+  let pa = Pcoq.Parsable.make ?loc stream in
   let sentence = Pcoq.Entry.parse entry pa in
   (sentence, [])
 [%%else]
-let parse_one_sentence stream ~st =
+let parse_one_sentence ?loc stream ~st =
   Vernacstate.Synterp.unfreeze st;
   Flags.record_comments := true;
   let entry = Pvernac.main_entry (Some (Synterp.get_default_proof_mode ())) in
-  let pa = Pcoq.Parsable.make stream in
+  let pa = Pcoq.Parsable.make ?loc stream in
   let sentence = Pcoq.Entry.parse entry pa in
   let comments = Pcoq.Parsable.comments pa in
   (sentence, comments)
@@ -340,7 +340,7 @@ let get_entry ast =
   Synterp.synterp_control ~intern ast
 [%%endif]
 
-let rec parse_more synterp_state stream raw parsed parsed_comments errors =
+let rec parse_more ?loc synterp_state stream raw parsed parsed_comments errors =
   let handle_parse_error start msg =
     log @@ "handling parse error at " ^ string_of_int start;
     let stop = Stream.count stream in
@@ -352,7 +352,7 @@ let rec parse_more synterp_state stream raw parsed parsed_comments errors =
   log @@ "Start of parse is: " ^ (string_of_int start);
   begin
     (* FIXME should we save lexer state? *)
-    match parse_one_sentence stream ~st:synterp_state with
+    match parse_one_sentence ?loc stream ~st:synterp_state with
     | None, _ (* EOI *) -> List.rev parsed, errors, List.rev parsed_comments
     | Some ast, comments ->
       let stop = Stream.count stream in
@@ -375,7 +375,7 @@ let rec parse_more synterp_state stream raw parsed parsed_comments errors =
           let parsed = sentence :: parsed in
           let comments = List.map (fun ((start, stop), content) -> {start; stop; content}) comments in
           let parsed_comments = List.append comments parsed_comments in
-          parse_more synterp_state stream raw parsed parsed_comments errors
+          parse_more ?loc:ast.loc synterp_state stream raw parsed parsed_comments errors
         with exn ->
           let e, info = Exninfo.capture exn in
           let loc = get_loc_from_info_or_exn exn in