not saving empty submodule's arity

it is not useful in general

Author: bobzhang

jscomp/core/builtin_cmj_datasets.ml

@@ -44,17 +44,17 @@ let rec get_arity (meta : Lam_stats.t) (lam : Lam.t) :  Lam_arity.t =
   | Lvar v -> arity_of_var meta v 
   | Lconst _ -> Lam_arity.non_function_arity_info
   | Llet(_,_,_, l ) -> get_arity meta l 
-  | Lprim {primitive = Pfield (_, Fld_module {name = fld_name}); 
+  | Lprim {primitive = Pfield (_, Fld_module {name }); 
            args =  [ Lglobal_module id  ]; _} -> 
-    begin match (Lam_compile_env.query_external_id_info id fld_name).arity with 
+    begin match (Lam_compile_env.query_external_id_info id name).arity with 
       | Single x -> x 
       | Submodule _ -> Lam_arity.na
     end
   | Lprim {primitive = Pfield (m,_); 
-           args =  [ Lprim{primitive = Pfield(n,Fld_module {name = fld_name}); 
+           args =  [ Lprim{primitive = Pfield(_,Fld_module {name }); 
                            args = [ Lglobal_module id]}  ]
           ; _} ->
-    begin match (Lam_compile_env.query_external_id_info id fld_name ).arity with 
+    begin match (Lam_compile_env.query_external_id_info id name).arity with 
       | Submodule subs -> subs.(m) (* TODO: shall we store it as array?*)
       | Single _ -> Lam_arity.na
     end

jscomp/core/lam_arity_analysis.ml

@@ -177,14 +177,14 @@ let rec
   compile_external_field (* Like [List.empty]*)
     (lamba_cxt : Lam_compile_context.t)
     (id : Ident.t)
-    pos
+    name
   : Js_output.t =  
-  match Lam_compile_env.query_external_id_info id pos  with      
+  match Lam_compile_env.query_external_id_info id name  with      
   | {  persistent_closed_lambda = Some lam}
       when Lam_util.not_function lam
       ->
       compile_lambda lamba_cxt lam     
-  | { name} ->
+  | _ ->
       Js_output.output_of_expression lamba_cxt.continuation  
       ~no_effects:no_effects_const
       (E.ml_var_dot id name )
@@ -254,7 +254,9 @@ and compile_external_field_apply
         E.call ~info:(call_info_of_ap_status ap_status) fn args 
       | App_na ->   
         match ident_info.arity with 
-        | Submodule _ -> E.call ~info:Js_call_info.dummy fn args 
+        | Submodule _ 
+        | Single Arity_na 
+          -> E.call ~info:Js_call_info.dummy fn args 
         | Single x -> 
           apply_with_arity
             fn ~arity:(Lam_arity.extract_arity x) args         

jscomp/core/lam_compile.ml

@@ -135,9 +135,8 @@ let simplify_alias
                   end
                 |  _ -> true 
               ) -> 
-          simpl @@
-          Lam_beta_reduce.propogate_beta_reduce
-            meta params body args
+          simpl (Lam_beta_reduce.propogate_beta_reduce
+                   meta params body args)
         | _ -> 
           Lam.apply (simpl l1) (Ext_list.map args simpl) loc status
 

jscomp/core/lam_pass_remove_alias.ml

@@ -99,9 +99,7 @@ let values_of_export
        match arity, persistent_closed_lambda with 
        | Single Arity_na, 
         (None | Some (Lconst (Const_pointer (_, Pt_module_alias)))) -> acc
-        (* TODO: empty module can be saved too
-           This is common since we have a module of externals quite common      
-         *)
+       | Submodule [||], None -> acc          
        | _ ->  
          let cmj_value : Js_cmj_format.cmj_value =  
            {arity ; persistent_closed_lambda } in  

jscomp/core/lam_stats_export.ml

@@ -6522,7 +6522,9 @@ type file_kind =
   | Upper_bs
   | Little_js 
   | Little_bs 
-  (** [js_name_of_modulename ~little A-Ns]
+  
+  
+(** [js_name_of_modulename ~little A-Ns]
   *)
 val js_name_of_modulename : 
   string -> 

lib/4.06.1/bsb.ml

@@ -3760,7 +3760,9 @@ type file_kind =
   | Upper_bs
   | Little_js 
   | Little_bs 
-  (** [js_name_of_modulename ~little A-Ns]
+  
+  
+(** [js_name_of_modulename ~little A-Ns]
   *)
 val js_name_of_modulename : 
   string -> 

lib/4.06.1/bsb_helper.ml

@@ -16393,7 +16393,9 @@ type file_kind =
   | Upper_bs
   | Little_js 
   | Little_bs 
-  (** [js_name_of_modulename ~little A-Ns]
+  
+  
+(** [js_name_of_modulename ~little A-Ns]
   *)
 val js_name_of_modulename : 
   string -> 

lib/4.06.1/unstable/all_ounit_tests.ml

@@ -6522,7 +6522,9 @@ type file_kind =
   | Upper_bs
   | Little_js 
   | Little_bs 
-  (** [js_name_of_modulename ~little A-Ns]
+  
+  
+(** [js_name_of_modulename ~little A-Ns]
   *)
 val js_name_of_modulename : 
   string ->