Treat @meth annotation as making the type uncurried.

This restores examples in the documentation that have been broken:
```res
type person = {@meth "say": (string, string) => unit}

@Val external john: person = "john"

john["say"]("hey", "jude")
```

Since there's no way in the `.res` syntax to call methods, the `@meth` annotation simply makes the type uncurried.

Author: cristianoc

CHANGELOG.md

@@ -51,6 +51,7 @@ These are only breaking changes for unformatted code.
 - Remove processing of objects expressions, which don't exist in `.res` syntax (`Pexp_object`) https://github.com/rescript-lang/rescript-compiler/pull/5841
 - Remove class type processing from compiler ppx https://github.com/rescript-lang/rescript-compiler/pull/5842
 - Remove method application via operator `##`, which does not exist in `.res` syntax https://github.com/rescript-lang/rescript-compiler/pull/5844
+- Treat `@meth` annotation as making the type uncurried for backwards compatibitly with some examples https://github.com/rescript-lang/rescript-compiler/pull/5845
 
 # 10.1.0-rc.6
 

jscomp/frontend/ast_core_type_class_type.ml

@@ -83,7 +83,9 @@ let typ_mapper (self : Bs_ast_mapper.mapper) (ty : Parsetree.core_type) =
       | Uncurry _ -> Ast_typ_uncurry.to_uncurry_type loc self label args body
       | Meth_callback _ ->
           Ast_typ_uncurry.to_method_callback_type loc self label args body
-      | Method _ -> Ast_typ_uncurry.to_method_type loc self label args body
+      | Method _ ->
+          (* Treat @meth as making the type uncurried, for backwards compatibility *)
+          Ast_typ_uncurry.to_uncurry_type loc self label args body
       | Nothing -> Bs_ast_mapper.default_mapper.typ self ty)
   | { ptyp_desc = Ptyp_object (methods, closed_flag); ptyp_loc = loc } ->
       let ( +> ) attr (typ : Parsetree.core_type) =

jscomp/main/builtin_cmi_datasets.ml

@@ -0,0 +1,6 @@
+'use strict';
+
+
+john.say("hey", "jude");
+
+/*  Not a pure module */

jscomp/test/build.ninja

@@ -0,0 +1,6 @@
+// The @meth annotation is for backwards compatibility. It just makes the type uncurried.
+type person = {@meth "say": (string, string) => unit}
+
+@val external john: person = "john"
+
+john["say"]("hey", "jude")