Test uncurried cast idea.

When curried application is used for an uncurried function, instead of a type error one gets a curried partial application.

This allows e.g. to define curried library functions such as `raise` and use them both with curried and uncurried application.

Author: cristianoc

jscomp/ml/typecore.ml

@@ -2988,6 +2988,7 @@ and type_application env funct (sargs : sargs) : targs * Types.type_expr =
                 Location.prerr_warning sarg1.pexp_loc Warnings.Unused_argument;
               unify env ty_fun (newty (Tarrow(l1,t1,t2,Clink(ref Cunknown))));
               (t1, t2)
+          | Tconstr (Pdot (Pdot(Pident {name = "Js"},"Fn",_),_,_),[{desc=Tarrow (l,t1,t2,_)}],_)
           | Tarrow (l,t1,t2,_) when Asttypes.same_arg_label l l1
             ->
               (t1, t2)

lib/4.06.1/unstable/js_compiler.ml

@@ -43686,6 +43686,7 @@ and type_application env funct (sargs : sargs) : targs * Types.type_expr =
                 Location.prerr_warning sarg1.pexp_loc Warnings.Unused_argument;
               unify env ty_fun (newty (Tarrow(l1,t1,t2,Clink(ref Cunknown))));
               (t1, t2)
+          | Tconstr (Pdot (Pdot(Pident {name = "Js"},"Fn",_),_,_),[{desc=Tarrow (l,t1,t2,_)}],_)
           | Tarrow (l,t1,t2,_) when Asttypes.same_arg_label l l1
             ->
               (t1, t2)

lib/4.06.1/unstable/js_playground_compiler.ml

@@ -43686,6 +43686,7 @@ and type_application env funct (sargs : sargs) : targs * Types.type_expr =
                 Location.prerr_warning sarg1.pexp_loc Warnings.Unused_argument;
               unify env ty_fun (newty (Tarrow(l1,t1,t2,Clink(ref Cunknown))));
               (t1, t2)
+          | Tconstr (Pdot (Pdot(Pident {name = "Js"},"Fn",_),_,_),[{desc=Tarrow (l,t1,t2,_)}],_)
           | Tarrow (l,t1,t2,_) when Asttypes.same_arg_label l l1
             ->
               (t1, t2)

lib/4.06.1/whole_compiler.ml

@@ -98681,6 +98681,7 @@ and type_application env funct (sargs : sargs) : targs * Types.type_expr =
                 Location.prerr_warning sarg1.pexp_loc Warnings.Unused_argument;
               unify env ty_fun (newty (Tarrow(l1,t1,t2,Clink(ref Cunknown))));
               (t1, t2)
+          | Tconstr (Pdot (Pdot(Pident {name = "Js"},"Fn",_),_,_),[{desc=Tarrow (l,t1,t2,_)}],_)
           | Tarrow (l,t1,t2,_) when Asttypes.same_arg_label l l1
             ->
               (t1, t2)