sync syntax

Author: cristianoc

CHANGELOG.md

@@ -20,6 +20,7 @@
 
 - Fix location issue in error messages with JSX V4 where the multiple props types are defined https://github.com/rescript-lang/syntax/pull/655
 - Fix location issue in make function in JSX V4 that breaks dead code elimination https://github.com/rescript-lang/syntax/pull/660
+- Fix parsing (hence pretty printing) of expressions with underscore `_` and comments.
 
 # 10.1.0-alpha.2
 

jscomp/napkin/CHANGELOG.md

@@ -30,6 +30,7 @@
 - Fix printing of comments inside empty blocks https://github.com/rescript-lang/syntax/pull/647
 - Fix location issue in error messages with JSX V4 where the multiple props types are defined https://github.com/rescript-lang/syntax/pull/655
 - Fix location issue in make function in JSX V4 that breaks dead code elimination https://github.com/rescript-lang/syntax/pull/660
+- Fix parsing (hence pretty printing) of expressions with underscore `_` and comments.
 
 ## ReScript 10.0
 

lib/4.06.1/unstable/js_playground_compiler.ml

@@ -283382,11 +283382,13 @@ let processUnderscoreApplication args =
     | _ -> arg
   in
   let args = List.map check_arg args in
-  let wrap exp_apply =
+  let wrap (exp_apply : Parsetree.expression) =
     match !exp_question with
     | Some {pexp_loc = loc} ->
       let pattern =
-        Ast_helper.Pat.mk (Ppat_var (Location.mkloc hidden_var loc)) ~loc
+        Ast_helper.Pat.mk
+          (Ppat_var (Location.mkloc hidden_var loc))
+          ~loc:Location.none
       in
       Ast_helper.Exp.mk (Pexp_fun (Nolabel, None, pattern, exp_apply)) ~loc
     | None -> exp_apply

lib/4.06.1/whole_compiler.ml

@@ -296906,11 +296906,13 @@ let processUnderscoreApplication args =
     | _ -> arg
   in
   let args = List.map check_arg args in
-  let wrap exp_apply =
+  let wrap (exp_apply : Parsetree.expression) =
     match !exp_question with
     | Some {pexp_loc = loc} ->
       let pattern =
-        Ast_helper.Pat.mk (Ppat_var (Location.mkloc hidden_var loc)) ~loc
+        Ast_helper.Pat.mk
+          (Ppat_var (Location.mkloc hidden_var loc))
+          ~loc:Location.none
       in
       Ast_helper.Exp.mk (Pexp_fun (Nolabel, None, pattern, exp_apply)) ~loc
     | None -> exp_apply