improve code gen for bs.this when this is not used, add a raw example for bs object

Author: Hongbo Zhang

jscomp/js_dump.ml

@@ -374,17 +374,25 @@ let rec pp_function method_
             formal_parameter_list inner_cxt  f (List.tl l) env )
         in
         P.space f ;
-        ignore @@ P.brace_vgroup f 1 (fun _ -> 
-            P.string f L.var ; 
-            P.space f; 
-            let cxt = ident cxt f (List.hd l) in 
-            P.space f ; 
-            P.string f L.eq ; 
-            P.space f ;
-            P.string f L.this;
-            P.space f ; 
-            semi f ; 
-            P.newline f ;
+        ignore @@ P.brace_vgroup f 1 (fun _ ->
+            let cxt =
+              if not (Js_fun_env.get_unused env 0) then
+                begin               
+                  P.string f L.var ; 
+                  P.space f; 
+                  let cxt = ident cxt f (List.hd l) in 
+                  P.space f ; 
+                  P.string f L.eq ; 
+                  P.space f ;
+                  P.string f L.this;
+                  P.space f ; 
+                  semi f ;
+                  P.newline f ;
+                  cxt ;                
+                end
+              else
+                cxt
+            in
             statement_list false cxt f b 
           );
 

jscomp/test/.depend

@@ -774,6 +774,8 @@ undef_regression_test.cmj : ../runtime/js_obj.cmj ../runtime/js.cmj
 undef_regression_test.cmx : ../runtime/js_obj.cmx ../runtime/js.cmx
 unitest_string.cmj :
 unitest_string.cmx :
+unsafe_obj_external.cmj : ../runtime/js.cmj
+unsafe_obj_external.cmx : ../runtime/js.cmx
 unsafe_ppx_test.cmj : mt.cmi ffi_js.cmj
 unsafe_ppx_test.cmx : mt.cmx ffi_js.cmx
 unsafe_this.cmj : ../runtime/js.cmj unsafe_this.cmi
@@ -1520,6 +1522,8 @@ undef_regression_test.cmo : ../runtime/js_obj.cmo ../runtime/js.cmo
 undef_regression_test.cmj : ../runtime/js_obj.cmj ../runtime/js.cmj
 unitest_string.cmo :
 unitest_string.cmj :
+unsafe_obj_external.cmo : ../runtime/js.cmo
+unsafe_obj_external.cmj : ../runtime/js.cmj
 unsafe_ppx_test.cmo : mt.cmi ffi_js.cmo
 unsafe_ppx_test.cmj : mt.cmj ffi_js.cmj
 unsafe_this.cmo : ../runtime/js.cmo unsafe_this.cmi

jscomp/test/test_bs_this.js

@@ -46,9 +46,14 @@ function f(x) {
             });
 }
 
+function u() {
+  return x;
+}
+
 exports.uux_this = uux_this;
 exports.even     = even;
 exports.bark     = bark;
 exports.js_obj   = js_obj;
 exports.f        = f;
+exports.u        = u;
 /* uux_this Not a pure module */

jscomp/test/test_bs_this.ml

@@ -39,3 +39,4 @@ let f (x : x ) =
     end
   end
 
+let u = fun [@bs.this] (_ : int) (x : int) -> x 

jscomp/test/unsafe_obj_external.js

@@ -0,0 +1,19 @@
+// GENERATED CODE BY BUCKLESCRIPT VERSION 0.9.0 , PLEASE EDIT WITH CARE
+'use strict';
+
+
+var v = {
+  x: function () {
+    return 3;
+  },
+  say: function (x) {
+    var self = this ;
+    return self.x() + x | 0;
+  }
+};
+
+var u = v.x() + v.say(3) | 0;
+
+exports.v = v;
+exports.u = u;
+/* v Not a pure module */

jscomp/test/unsafe_obj_external.ml

@@ -0,0 +1,34 @@
+
+
+
+external config :
+  x : ('self_type -> 'x [@bs.this]) ->
+  say :('self_type  -> 'x -> 'say [@bs.this]) ->
+  unit ->
+  (<
+     x : unit -> 'x [@bs.meth];
+     say : 'x -> 'say [@bs.meth]      
+  > Js.t as 'self_type)  = "" [@@bs.obj] 
+
+
+let v =
+  let x = 3 in   
+  config
+    ~x:(fun [@bs.this] _ -> x )
+    ~say:(fun [@bs.this] self x -> self##x () + x)
+    ()
+
+(** 
+let x = 3 in
+object (self : 'self_type)
+   method x = x 
+   method say x = self##x + x 
+end [@bs]
+*)
+let u =
+  v##x () + v##say 3 
+
+  
+(* local variables: *)
+(* compile-command: "bsc -I ../runtime -drawlambda  unsafe_obj_external.ml" *)
+(* end: *)