Workaround for @asin labels in uncurried externals.

CHANGELOG.md

@@ -22,6 +22,7 @@
 - GenType: only export types (not values) from module types. https://github.com/rescript-lang/rescript-compiler/pull/6516
 - Fix compiler crash with unboxed variant definition with only 1 constructor. https://github.com/rescript-lang/rescript-compiler/pull/6523
 - GenType: support mutual recursive types inside modules. https://github.com/rescript-lang/rescript-compiler/pull/6528
+- Workaround for `@as`in labels in uncurried externals, which was broken. https://github.com/rescript-lang/rescript-compiler/pull/6527
 
 # 11.0.0-rc.7
 

jscomp/syntax/src/res_core.ml

@@ -151,6 +151,10 @@ module ErrorMessages = struct
      mean `#" ^ number ^ "`?"
 end
 
+module InExternal = struct
+  let status = ref false
+end
+
 let jsxAttr = (Location.mknoloc "JSX", Parsetree.PStr [])
 let uncurriedAppAttr = (Location.mknoloc "res.uapp", Parsetree.PStr [])
 let ternaryAttr = (Location.mknoloc "res.ternary", Parsetree.PStr [])
@@ -4276,6 +4280,22 @@ and parseEs6ArrowType ~attrs p =
             p.uncurried_config |> Res_uncurried.fromDotted ~dotted
           in
           let loc = mkLoc startPos endPos in
+          let arity =
+            (* Workaround for ~lbl: @as(json`false`) _, which changes the arity *)
+            match argLbl with
+            | Labelled _s ->
+              let typ_is_any =
+                match typ.ptyp_desc with
+                | Ptyp_any -> true
+                | _ -> false
+              in
+              let has_as =
+                Ext_list.exists typ.ptyp_attributes (fun (x, _) -> x.txt = "as")
+              in
+              if !InExternal.status && typ_is_any && has_as then arity - 1
+              else arity
+            | _ -> arity
+          in
           let tArg = Ast_helper.Typ.arrow ~loc ~attrs argLbl typ t in
           if uncurried && (paramNum = 1 || p.uncurried_config = Legacy) then
             (paramNum - 1, Ast_uncurried.uncurriedType ~loc ~arity tArg, 1)
@@ -5441,6 +5461,8 @@ and parseTypeDefinitionOrExtension ~attrs p =
 
 (* external value-name : typexp = external-declaration *)
 and parseExternalDef ~attrs ~startPos p =
+  let inExternal = !InExternal.status in
+  InExternal.status := true;
   Parser.leaveBreadcrumb p Grammar.External;
   Parser.expect Token.External p;
   let name, loc = parseLident p in
@@ -5465,6 +5487,7 @@ and parseExternalDef ~attrs ~startPos p =
   let loc = mkLoc startPos p.prevEndPos in
   let vb = Ast_helper.Val.mk ~loc ~attrs ~prim name typExpr in
   Parser.eatBreadcrumb p;
+  InExternal.status := inExternal;
   vb
 
 (* constr-def ::=

jscomp/test/AsInUncurriedExternals.res

@@ -0,0 +1,16 @@
+@@uncurried
+
+@obj
+external makeOptions: (
+  ~objectMode: @as(json`false`) _,
+  ~name: string,
+  ~someOther: @as(json`true`) _,
+  unit,
+) => int = ""
+
+let mo = makeOptions
+
+let options = mo(~name="foo", ())
+
+let shouldNotFail: (~objectMode: @as(json`false`) _, ~name: string) => int = (~objectMode, ~name) =>
+  3