add bs-unafe-empty-array

Author: bobzhang

jscomp/common/js_config.ml

@@ -114,4 +114,6 @@ let no_export = ref false
 
 let record_as_js_object = ref false (* otherwise has an attribute *)
 
-let as_ppx = ref false
+let as_ppx = ref false
+
+let mono_empty_array = ref true

jscomp/common/js_config.mli

@@ -109,4 +109,6 @@ val all_module_aliases : bool ref
 val no_stdlib: bool ref
 val no_export: bool ref
 val record_as_js_object : bool ref
-val as_ppx : bool ref 
+val as_ppx : bool ref 
+
+val mono_empty_array : bool ref

jscomp/main/js_main.ml

@@ -206,8 +206,8 @@ let buckle_script_flags : (string * Arg.spec * string) list =
      " Define conditional variable e.g, -D DEBUG=true"
   )
   ::
-  ("-bs-quiet", Arg.Unit (fun _ -> ()),
-    " (Deprecated using -w a) Quiet mode (no warnings printed)"
+  ("-bs-unsafe-empty-array", Arg.Clear Js_config.mono_empty_array,
+    " Allow [||] to be polymorphic"
   )
   ::
   ("-nostdlib", Arg.Set Js_config.no_stdlib,

jscomp/syntax/bs_builtin_ppx.ml

@@ -76,7 +76,7 @@ let expr_mapper  (self : mapper) (e : Parsetree.expression) =
             (s, (Some delim)))
           ->
             Ast_utf8_string_interp.transform e s delim
-        | Pexp_array [] when 
+        | Pexp_array [] when !Js_config.mono_empty_array &&
           not (Ext_list.exists e.pexp_attributes (fun ({txt},_) -> txt = ""))->  
         (* `ocamlfind query ppx_tools`/dumpast -loc_underscore -e 'let emptyArray () = [||] in emptyArray ()'*)          
           let loc = e.pexp_loc in

jscomp/test/build.ninja

@@ -465,6 +465,7 @@ build test/parser_api.cmi test/parser_api.cmj : cc test/parser_api.ml | $stdlib
 build test/parser_api_test.cmi test/parser_api_test.cmj : cc test/parser_api_test.ml | test/mt.cmj test/parser_api.cmj $stdlib
 build test/pipe_send_readline.cmi test/pipe_send_readline.cmj : cc test/pipe_send_readline.ml | $stdlib
 build test/pipe_syntax.cmi test/pipe_syntax.cmj : cc test/pipe_syntax.ml | $stdlib
+build test/poly_empty_array.cmi test/poly_empty_array.cmj : cc test/poly_empty_array.ml | $stdlib
 build test/poly_type.cmi test/poly_type.cmj : cc test/poly_type.ml | $stdlib
 build test/poly_variant_test.cmj : cc_cmi test/poly_variant_test.ml | test/mt.cmj test/poly_variant_test.cmi $stdlib
 build test/poly_variant_test.cmi : cc test/poly_variant_test.mli | $stdlib

jscomp/test/poly_empty_array.js

@@ -0,0 +1,7 @@
+'use strict';
+
+
+var a = [];
+
+exports.a = a;
+/* No side effect */

jscomp/test/poly_empty_array.ml

@@ -0,0 +1,3 @@
+
+[@@@bs.config  {flags = [|"-bs-unsafe-empty-array"|] } ]
+let a = [||]

lib/4.06.1/unstable/all_ounit_tests.ml

@@ -7776,6 +7776,8 @@ val no_stdlib: bool ref
 val no_export: bool ref
 val record_as_js_object : bool ref
 val as_ppx : bool ref 
+
+val mono_empty_array : bool ref
 end = struct
 #1 "js_config.ml"
 (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
@@ -7895,6 +7897,8 @@ let no_export = ref false
 let record_as_js_object = ref false (* otherwise has an attribute *)
 
 let as_ppx = ref false
+
+let mono_empty_array = ref true
 end
 module Map_gen
 = struct

lib/4.06.1/unstable/bspack.ml

@@ -11351,6 +11351,8 @@ val no_stdlib: bool ref
 val no_export: bool ref
 val record_as_js_object : bool ref
 val as_ppx : bool ref 
+
+val mono_empty_array : bool ref
 end = struct
 #1 "js_config.ml"
 (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
@@ -11470,6 +11472,8 @@ let no_export = ref false
 let record_as_js_object = ref false (* otherwise has an attribute *)
 
 let as_ppx = ref false
+
+let mono_empty_array = ref true
 end
 module Map_gen
 = struct

lib/4.06.1/unstable/js_compiler.ml

@@ -298844,6 +298844,8 @@ val no_stdlib: bool ref
 val no_export: bool ref
 val record_as_js_object : bool ref
 val as_ppx : bool ref 
+
+val mono_empty_array : bool ref
 end = struct
 #1 "js_config.ml"
 (* Copyright (C) 2015-2016 Bloomberg Finance L.P.
@@ -298963,6 +298965,8 @@ let no_export = ref false
 let record_as_js_object = ref false (* otherwise has an attribute *)
 
 let as_ppx = ref false
+
+let mono_empty_array = ref true
 end
 module Ast_config : sig 
 #1 "ast_config.mli"
@@ -308258,7 +308262,7 @@ let expr_mapper  (self : mapper) (e : Parsetree.expression) =
             (s, (Some delim)))
           ->
             Ast_utf8_string_interp.transform e s delim
-        | Pexp_array [] when 
+        | Pexp_array [] when !Js_config.mono_empty_array &&
           not (Ext_list.exists e.pexp_attributes (fun ({txt},_) -> txt = ""))->  
         (* `ocamlfind query ppx_tools`/dumpast -loc_underscore -e 'let emptyArray () = [||] in emptyArray ()'*)          
           let loc = e.pexp_loc in