Fix regex literal loc (#7683)

* fix regex literal loc

* changelog

* more sane fix

Author: zth

CHANGELOG.md

@@ -34,6 +34,7 @@
 
 - Fix `--create-sourcedirs` generation with for a single project. https://github.com/rescript-lang/rescript/pull/7671
 - Fix rewatch not recompiling on changes under windows. https://github.com/rescript-lang/rescript/pull/7690
+- Fix locations of regex literals. https://github.com/rescript-lang/rescript/pull/7683
 
 # 12.0.0-beta.2
 

compiler/syntax/src/res_core.ml

@@ -1812,8 +1812,7 @@ and parse_constrained_expr_region p =
     | _ -> Some expr)
   | _ -> None
 
-and parse_regex p pattern flags =
-  let start_pos = p.Parser.start_pos in
+and parse_regex ~start_pos p pattern flags =
   Parser.next p;
   let loc = mk_loc start_pos p.prev_end_pos in
   let payload =
@@ -1826,7 +1825,7 @@ and parse_regex p pattern flags =
                   if p.mode = ParseForTypeChecker then Some "js" else None )));
       ]
   in
-  Ast_helper.Exp.extension (Location.mknoloc "re", payload)
+  Ast_helper.Exp.extension (Location.mkloc "re" loc, payload)
 
 (* Atomic expressions represent unambiguous expressions.
  * This means that regardless of the context, these expressions
@@ -1903,13 +1902,13 @@ and parse_atomic_expr p =
     | Forwardslash -> (
       Parser.next_regex_token p;
       match p.token with
-      | Regex (pattern, flags) -> parse_regex p pattern flags
+      | Regex (pattern, flags) -> parse_regex ~start_pos p pattern flags
       | _ -> Ast_helper.Exp.extension (Location.mknoloc "re", Parsetree.PStr [])
       )
     | ForwardslashDot -> (
       Parser.next_regex_token p;
       match p.token with
-      | Regex (pattern, flags) -> parse_regex p ("." ^ pattern) flags
+      | Regex (pattern, flags) -> parse_regex ~start_pos p ("." ^ pattern) flags
       | _ -> Ast_helper.Exp.extension (Location.mknoloc "re", Parsetree.PStr [])
       )
     | token -> (

tests/build_tests/super_errors/expected/extract_from_none_file.res.expected renamed to tests/build_tests/super_errors/expected/regex_literal.res.expected

@@ -1,6 +1,10 @@
 
   We've found a bug for you!
-  /.../fixtures/extract_from_none_file.res
+  /.../fixtures/regex_literal.res:1:7-11
+
+  1 │ while /foo/ {
+  2 │   ()
+  3 │ }
 
   This has type: RegExp.t
   But a while loop condition must always be of type: bool

tests/build_tests/super_errors/fixtures/extract_from_none_file.res

@@ -0,0 +1,3 @@
+while /foo/ {
+  ()
+}