Error source highlighting: align using tabs to match tabs in the source

Fixes #9116
ocaml · Nov 13, 2019 · c0546bb · c0546bb
1 parent 7e842f6
commit c0546bb
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Showing 2 changed files with 8 additions and 4 deletions.
diff --git a/parsing/location.ml b/parsing/location.ml
@@ -463,14 +463,18 @@ let highlight_quote ppf
         (* Single-line error *)
         Format.fprintf ppf "%s | %s@," line_nb line;
         Format.fprintf ppf "%*s   " (String.length line_nb) "";
-        for pos = line_start_cnum to rightmost.pos_cnum - 1 do
+        String.iteri (fun i car ->
+          let pos = line_start_cnum + i in
           if ISet.is_start iset ~pos <> None then
             Format.fprintf ppf "@{<%s>" highlight_tag;
           if ISet.mem iset ~pos then Format.pp_print_char ppf '^'
-          else Format.pp_print_char ppf ' ';
+            (* For alignment purposes, align using a tab for each tab in the
+               source code *)
+          else if car = '\t' then Format.pp_print_char ppf '\t'
+          else if pos < rightmost.pos_cnum then Format.pp_print_char ppf ' ';
           if ISet.is_end iset ~pos <> None then
             Format.fprintf ppf "@}"
-        done;
+        ) line;
         Format.fprintf ppf "@}@,"
     | _ ->
         (* Multi-line error *)

diff --git a/testsuite/tests/messages/highlight_tabs.ml b/testsuite/tests/messages/highlight_tabs.ml
@@ -7,7 +7,7 @@
 [%%expect{|
 Line 1, characters 10-13:
 1 | 		let x = abc
-              ^^^
+    		        ^^^
 Error: Unbound value abc
 Hint: Did you mean abs?
 |}];;