erb.rb: deprecate safe_level of ERB.new

Also, as it's in the middle of the list of 4 arguments, 3rd and 4th arguments
(trim_mode, eoutvar) are changed to keyword arguments.
Old ways to specify arguments are deprecated and warned now.

bin/erb: deprecate -S option.

We'll remove all of deprecated ones at Ruby 2.7+.

enc/make_encmake.rb: stopped using deprecated interface
ext/etc/mkconstants.rb: ditto
ext/socket/mkconstants.rb: ditto
sample/ripper/ruby2html.rb: ditto
spec/ruby/library/erb/defmethod/def_erb_method_spec.rb: ditto
spec/ruby/library/erb/new_spec.rb: ditto
test/erb/test_erb.rb: ditto
test/erb/test_erb_command.rb: ditto
tool/generic_erb.rb: ditto
tool/ruby_vm/helpers/dumper.rb: ditto
tool/transcode-tblgen.rb: ditto
lib/rdoc/erbio.rb: ditto
lib/rdoc/generator/darkfish.rb: ditto

[Feature #14256]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62529 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

16 files changed, 236 insertions, 70 deletions

diff --git a/NEWS b/NEWS
index c846fcbb45..2e36f5b61c 100644
--- a/NEWS
+++ b/NEWS
@@ -69,6 +69,11 @@ with all sufficient information, see the ChangeLog file or Redmine
 
 === Stdlib updates (outstanding ones only)
 
+* ERB
+
+  * 2nd, 3rd and 4th arguments of ERB.new are deprecated. 2nd argument (safe_level) will be dropped in the future
+    and some of those arguments (trim_mode, eoutvar) are changed to keyword arguments. [Feature #14256]
+
 * Matrix
 
   * New method:
diff --git a/bin/erb b/bin/erb
index 86f7042fae..d060caba90 100755
--- a/bin/erb
+++ b/bin/erb
@@ -75,6 +75,7 @@ class ERB
           when '-r'                        # require
             require ARGV.req_arg
           when '-S'                        # security level
+            warn 'warning: -S option of erb command is deprecated. Please do not use this.'
             arg = ARGV.req_arg
             raise "invalid safe_level #{arg.dump}" unless arg =~ /\A[0-1]\z/
             safe_level = arg.to_i
@@ -112,7 +113,6 @@ class ERB
   -v               enable verbose mode
   -d               set $DEBUG to true
   -r library       load a library
-  -S safe_level    set $SAFE (0..1)
   -E ex[:in]       set default external/internal encodings
   -U               set default encoding to UTF-8.
   -T trim_mode     specify trim_mode (0..2, -)
@@ -127,7 +127,12 @@ EOU
       filename = $FILENAME
       exit 2 unless src
       trim = trim_mode_opt(trim_mode, disable_percent)
-      erb = factory.new(src.untaint, safe_level, trim)
+      if safe_level.nil?
+        erb = factory.new(src.untaint, trim_mode: trim)
+      else
+        # [deprecated] This will be removed at Ruby 2.7.
+        erb = factory.new(src.untaint, safe_level, trim_mode: trim)
+      end
       erb.filename = filename
       if output
         if number
diff --git a/enc/make_encmake.rb b/enc/make_encmake.rb
index 4ab85f36e3..06979dbad7 100755
--- a/enc/make_encmake.rb
+++ b/enc/make_encmake.rb
@@ -121,7 +121,11 @@ ENCS, ENC_DEPS = target_encodings
 ATRANS, TRANS = target_transcoders
 
 if File.exist?(depend = File.join($srcdir, "depend"))
-  erb = ERB.new(File.read(depend), nil, '%')
+  if RUBY_VERSION >= '2.6'
+    erb = ERB.new(File.read(depend), trim_mode: '%')
+  else
+    erb = ERB.new(File.read(depend), nil, '%')
+  end
   erb.filename = depend
   tmp = erb.result(binding)
   dep = "\n#### depend ####\n\n" << depend_rules(tmp).join
@@ -135,7 +139,11 @@ open(ARGV[0], 'wb') {|f|
 }
 if MODULE_TYPE == :static
   filename = "encinit.c.erb"
-  erb = ERB.new(File.read(File.join($srcdir, filename)), nil, '%-')
+  if RUBY_VERSION >= '2.6'
+    erb = ERB.new(File.read(File.join($srcdir, filename)), trim_mode: '%-')
+  else
+    erb = ERB.new(File.read(File.join($srcdir, filename)), nil, '%-')
+  end
   erb.filename = "enc/#{filename}"
   tmp = erb.result(binding)
   begin
diff --git a/ext/etc/mkconstants.rb b/ext/etc/mkconstants.rb
index 18f34c9875..69b472d682 100644
--- a/ext/etc/mkconstants.rb
+++ b/ext/etc/mkconstants.rb
@@ -66,7 +66,15 @@ def each_name(pat)
   }
 end
 
-ERB.new(<<'EOS', nil, '%').def_method(Object, "gen_const_decls")
+erb_new = lambda do |src, safe, trim|
+  if RUBY_VERSION >= '2.6'
+    ERB.new(src, trim_mode: trim)
+  else
+    ERB.new(src, safe, trim)
+  end
+end
+
+erb_new.call(<<'EOS', nil, '%').def_method(Object, "gen_const_decls")
 % each_const {|name, default_value|
 #if !defined(<%=name%>)
 # if defined(HAVE_CONST_<%=name.upcase%>)
@@ -80,7 +88,7 @@ ERB.new(<<'EOS', nil, '%').def_method(Object, "gen_const_decls")
 % }
 EOS
 
-ERB.new(<<'EOS', nil, '%').def_method(Object, "gen_const_defs")
+erb_new.call(<<'EOS', nil, '%').def_method(Object, "gen_const_defs")
 % each_const {|name, default_value|
 #if defined(<%=name%>)
 %   if comment = COMMENTS[name]
@@ -91,13 +99,13 @@ ERB.new(<<'EOS', nil, '%').def_method(Object, "gen_const_defs")
 % }
 EOS
 
-header_result = ERB.new(<<'EOS', nil, '%').result(binding)
+header_result = erb_new.call(<<'EOS', nil, '%').result(binding)
 /* autogenerated file */
 
 <%= gen_const_decls %>
 EOS
 
-result = ERB.new(<<'EOS', nil, '%').result(binding)
+result = erb_new.call(<<'EOS', nil, '%').result(binding)
 /* autogenerated file */
 
 #ifdef HAVE_LONG_LONG
diff --git a/ext/socket/mkconstants.rb b/ext/socket/mkconstants.rb
index 0ebf628b46..86e0453ae8 100644
--- a/ext/socket/mkconstants.rb
+++ b/ext/socket/mkconstants.rb
@@ -73,7 +73,15 @@ def each_name(pat)
   }
 end
 
-ERB.new(<<'EOS', nil, '%').def_method(Object, "gen_const_decls")
+erb_new = lambda do |src, safe, trim|
+  if RUBY_VERSION >= '2.6'
+    ERB.new(src, trim_mode: trim)
+  else
+    ERB.new(src, safe, trim)
+  end
+end
+
+erb_new.call(<<'EOS', nil, '%').def_method(Object, "gen_const_decls")
 % each_const {|guard, name, default_value|
 #if !defined(<%=name%>)
 # if defined(HAVE_CONST_<%=name.upcase%>)
@@ -87,7 +95,7 @@ ERB.new(<<'EOS', nil, '%').def_method(Object, "gen_const_decls")
 % }
 EOS
 
-ERB.new(<<'EOS', nil, '%').def_method(Object, "gen_const_defs_in_guard(name, default_value)")
+erb_new.call(<<'EOS', nil, '%').def_method(Object, "gen_const_defs_in_guard(name, default_value)")
 #if defined(<%=name%>)
     /* <%= COMMENTS[name] %> */
     rb_define_const(rb_cSocket, <%=c_str name%>, INTEGER2NUM(<%=name%>));
@@ -96,7 +104,7 @@ ERB.new(<<'EOS', nil, '%').def_method(Object, "gen_const_defs_in_guard(name, def
 #endif
 EOS
 
-ERB.new(<<'EOS', nil, '%').def_method(Object, "gen_const_defs")
+erb_new.call(<<'EOS', nil, '%').def_method(Object, "gen_const_defs")
 % each_const {|guard, name, default_value|
 %   if guard
 #if <%=guard%>
@@ -146,7 +154,7 @@ def each_names_with_len(pat, prefix_optional=nil)
   }
 end
 
-ERB.new(<<'EOS', nil, '%').def_method(Object, "gen_name_to_int_decl(funcname, pat, prefix_optional, guard=nil)")
+erb_new.call(<<'EOS', nil, '%').def_method(Object, "gen_name_to_int_decl(funcname, pat, prefix_optional, guard=nil)")
 %if guard
 #ifdef <%=guard%>
 int <%=funcname%>(const char *str, long len, int *valp);
@@ -156,7 +164,7 @@ int <%=funcname%>(const char *str, long len, int *valp);
 %end
 EOS
 
-ERB.new(<<'EOS', nil, '%').def_method(Object, "gen_name_to_int_func_in_guard(funcname, pat, prefix_optional, guard=nil)")
+erb_new.call(<<'EOS', nil, '%').def_method(Object, "gen_name_to_int_func_in_guard(funcname, pat, prefix_optional, guard=nil)")
 int
 <%=funcname%>(const char *str, long len, int *valp)
 {
@@ -177,7 +185,7 @@ int
 }
 EOS
 
-ERB.new(<<'EOS', nil, '%').def_method(Object, "gen_name_to_int_func(funcname, pat, prefix_optional, guard=nil)")
+erb_new.call(<<'EOS', nil, '%').def_method(Object, "gen_name_to_int_func(funcname, pat, prefix_optional, guard=nil)")
 %if guard
 #ifdef <%=guard%>
 <%=gen_name_to_int_func_in_guard(funcname, pat, prefix_optional, guard)%>
@@ -206,7 +214,7 @@ def reverse_each_name_with_prefix_optional(pat, prefix_pat)
   end
 end
 
-ERB.new(<<'EOS', nil, '%').def_method(Object, "gen_int_to_name_hash(hash_var, pat, prefix_pat)")
+erb_new.call(<<'EOS', nil, '%').def_method(Object, "gen_int_to_name_hash(hash_var, pat, prefix_pat)")
     <%=hash_var%> = st_init_numtable();
 % reverse_each_name_with_prefix_optional(pat, prefix_pat) {|n,s|
 #ifdef <%=n%>
@@ -215,7 +223,7 @@ ERB.new(<<'EOS', nil, '%').def_method(Object, "gen_int_to_name_hash(hash_var, pa
 % }
 EOS
 
-ERB.new(<<'EOS', nil, '%').def_method(Object, "gen_int_to_name_func(func_name, hash_var)")
+erb_new.call(<<'EOS', nil, '%').def_method(Object, "gen_int_to_name_func(func_name, hash_var)")
 ID
 <%=func_name%>(int val)
 {
@@ -226,7 +234,7 @@ ID
 }
 EOS
 
-ERB.new(<<'EOS', nil, '%').def_method(Object, "gen_int_to_name_decl(func_name, hash_var)")
+erb_new.call(<<'EOS', nil, '%').def_method(Object, "gen_int_to_name_decl(func_name, hash_var)")
 ID <%=func_name%>(int val);
 EOS
 
@@ -275,7 +283,7 @@ def_intern('rsock_intern_udp_optname',  /\AUDP_/, "UDP_")
 def_intern('rsock_intern_scm_optname',  /\ASCM_/, "SCM_")
 def_intern('rsock_intern_local_optname',  /\ALOCAL_/, "LOCAL_")
 
-result = ERB.new(<<'EOS', nil, '%').result(binding)
+result = erb_new.call(<<'EOS', nil, '%').result(binding)
 /* autogenerated file */
 
 <%= INTERN_DEFS.map {|vardef, gen_hash, decl, func| vardef }.join("\n") %>
@@ -318,7 +326,7 @@ init_constants(void)
 
 EOS
 
-header_result = ERB.new(<<'EOS', nil, '%').result(binding)
+header_result = erb_new.call(<<'EOS', nil, '%').result(binding)
 /* autogenerated file */
 <%= gen_const_decls %>
 <%= NAME_TO_INT_DEFS.map {|decl, func| decl }.join("\n") %>
diff --git a/lib/erb.rb b/lib/erb.rb
index 215a3f516f..c50d3eac48 100644
--- a/lib/erb.rb
+++ b/lib/erb.rb
@@ -115,7 +115,7 @@ require "cgi/util"
 #     James Edward Gray II
 #   }.gsub(/^  /, '')
 #
-#   message = ERB.new(template, 0, "%<>")
+#   message = ERB.new(template, trim_mode: "%<>")
 #
 #   # Set up template data.
 #   to = "Community Spokesman <spokesman@ruby_community.org>"
@@ -263,7 +263,7 @@ class ERB
 
   # Returns revision information for the erb.rb module.
   def self.version
-    "erb.rb [2.1.0 #{ERB::Revision.split[1]}]"
+    "erb.rb [2.2.0 #{ERB::Revision.split[1]}]"
   end
 end
 
@@ -777,11 +777,11 @@ class ERB
   #    def build
   #      b = binding
   #      # create and run templates, filling member data variables
-  #      ERB.new(<<-'END_PRODUCT'.gsub(/^\s+/, ""), 0, "", "@product").result b
+  #      ERB.new(<<-'END_PRODUCT'.gsub(/^\s+/, ""), trim_mode: "", eoutvar: "@product").result b
   #        <%= PRODUCT[:name] %>
   #        <%= PRODUCT[:desc] %>
   #      END_PRODUCT
-  #      ERB.new(<<-'END_PRICE'.gsub(/^\s+/, ""), 0, "", "@price").result b
+  #      ERB.new(<<-'END_PRICE'.gsub(/^\s+/, ""), trim_mode: "", eoutvar: "@price").result b
   #        <%= PRODUCT[:name] %> -- <%= PRODUCT[:cost] %>
   #        <%= PRODUCT[:desc] %>
   #      END_PRICE
@@ -802,7 +802,22 @@ class ERB
   #  Chicken Fried Steak -- 9.95
   #  A well messages pattie, breaded and fried.
   #
-  def initialize(str, safe_level=nil, trim_mode=nil, eoutvar='_erbout')
+  def initialize(str, safe_level=NOT_GIVEN, legacy_trim_mode=NOT_GIVEN, legacy_eoutvar=NOT_GIVEN, trim_mode: nil, eoutvar: '_erbout')
+    # Complex initializer for $SAFE deprecation at Feature #14256, which should be removed at Ruby 2.7.
+    if safe_level != NOT_GIVEN
+      warn 'warning: Passing safe_level with the 2nd argument of ERB.new is deprecated. Do not use it, and specify other arguments as keyword arguments.'
+    else
+      safe_level = nil
+    end
+    if legacy_trim_mode != NOT_GIVEN
+      warn 'warning: Passing trim_mode with the 3rd argument of ERB.new is deprecated. Use keyword argument like ERB.new(str, trim_mode: ...) instead.'
+      trim_mode = legacy_trim_mode
+    end
+    if legacy_eoutvar != NOT_GIVEN
+      warn 'warning: Passing eoutvar with the 4th argument of ERB.new is deprecated. Use keyword argument like ERB.new(str, eoutvar: ...) instead.'
+      eoutvar = legacy_eoutvar
+    end
+
     @safe_level = safe_level
     compiler = make_compiler(trim_mode)
     set_eoutvar(compiler, eoutvar)
@@ -810,6 +825,8 @@ class ERB
     @filename = nil
     @lineno = 0
   end
+  NOT_GIVEN = Object.new
+  private_constant :NOT_GIVEN
 
   ##
   # Creates a new compiler for ERB.  See ERB::Compiler.new for details
diff --git a/lib/rdoc/erbio.rb b/lib/rdoc/erbio.rb
index 42ce895fb3..2ebce9519f 100644
--- a/lib/rdoc/erbio.rb
+++ b/lib/rdoc/erbio.rb
@@ -21,7 +21,11 @@ class RDoc::ERBIO < ERB
   # Defaults +eoutvar+ to 'io', otherwise is identical to ERB's initialize
 
   def initialize str, safe_level = nil, trim_mode = nil, eoutvar = 'io'
-    super
+    if RUBY_VERSION >= '2.6'
+      super(str, trim_mode: trim_mode, eoutvar: eoutvar)
+    else
+      super
+    end
   end
 
   ##
diff --git a/lib/rdoc/generator/darkfish.rb b/lib/rdoc/generator/darkfish.rb
index bf4eb1f530..a07f74e716 100644
--- a/lib/rdoc/generator/darkfish.rb
+++ b/lib/rdoc/generator/darkfish.rb
@@ -778,7 +778,11 @@ class RDoc::Generator::Darkfish
       erbout = "_erbout_#{file_var}"
     end
 
-    template = klass.new template, nil, '<>', erbout
+    if RUBY_VERSION >= '2.6'
+      template = klass.new template, trim_mode: '<>', eoutvar: erbout
+    else
+      template = klass.new template, nil, '<>', erbout
+    end
     @template_cache[file] = template
     template
   end
diff --git a/sample/ripper/ruby2html.rb b/sample/ripper/ruby2html.rb
index 8f64f5a713..1e6b3bf550 100644
--- a/sample/ripper/ruby2html.rb
+++ b/sample/ripper/ruby2html.rb
@@ -73,7 +73,11 @@ class ERB
 end
 
 def ruby2html(f, encoding, css, print_line_number)
-  erb = ERB.new(TEMPLATE, nil, '>')
+  if RUBY_VERSION >= '2.6'
+    erb = ERB.new(TEMPLATE, trim_mode: '>')
+  else
+    erb = ERB.new(TEMPLATE, nil, '>')
+  end
   erb.filename = __FILE__
   erb.lineno = TEMPLATE_LINE
   erb.result(binding())
diff --git a/spec/ruby/library/erb/defmethod/def_erb_method_spec.rb b/spec/ruby/library/erb/defmethod/def_erb_method_spec.rb
index e1eca2fbef..6c465936c1 100644
--- a/spec/ruby/library/erb/defmethod/def_erb_method_spec.rb
+++ b/spec/ruby/library/erb/defmethod/def_erb_method_spec.rb
@@ -50,7 +50,11 @@ END
     MY_INPUT4_FOR_ERB = input
     class MyClass4ForErb
       extend ERB::DefMethod
-      erb = ERB.new(MY_INPUT4_FOR_ERB, nil, '<>')
+      if RUBY_VERSION >= '2.6'
+        erb = ERB.new(MY_INPUT4_FOR_ERB, trim_mode: '<>')
+      else
+        erb = ERB.new(MY_INPUT4_FOR_ERB, nil, '<>')
+      end
       def_erb_method('render()', erb)
       def initialize(items)
         @items = items
diff --git a/spec/ruby/library/erb/new_spec.rb b/spec/ruby/library/erb/new_spec.rb
index f141f1c00e..156873a598 100644
--- a/spec/ruby/library/erb/new_spec.rb
+++ b/spec/ruby/library/erb/new_spec.rb
@@ -31,21 +31,33 @@ END
   it "compiles eRuby script into ruby code when trim mode is 0 or not specified" do
     expected = "<ul>\n\n\n\n<li>1</li>\n\n\n\n<li>2</li>\n\n\n\n<li>3</li>\n\n\n</ul>\n"
     [0, '', nil].each do |trim_mode|
-      ERB.new(@eruby_str, nil, trim_mode).result.should == expected
+      if RUBY_VERSION >= '2.6'
+        ERB.new(@eruby_str, trim_mode: trim_mode).result.should == expected
+      else
+        ERB.new(@eruby_str, nil, trim_mode).result.should == expected
+      end
     end
   end
 
   it "removes '\n' when trim_mode is 1 or '>'" do
     expected = "<ul>\n<li>1</li>\n<li>2</li>\n<li>3</li>\n</ul>\n"
     [1, '>'].each do |trim_mode|
-      ERB.new(@eruby_str, nil, trim_mode).result.should == expected
+      if RUBY_VERSION >= '2.6'
+        ERB.new(@eruby_str, trim_mode: trim_mode).result.should == expected
+      else
+        ERB.new(@eruby_str, nil, trim_mode).result.should == expected
+      end
     end
   end
 
   it "removes spaces at beginning of line and '\n' when trim_mode is 2 or '<>'" do
     expected = "<ul>\n<li>1</li>\n<li>2</li>\n<li>3</li>\n</ul>\n"
     [2, '<>'].each do |trim_mode|
-      ERB.new(@eruby_str, nil, trim_mode).result.should == expected
+      if RUBY_VERSION >= '2.6'
+        ERB.new(@eruby_str, trim_mode: trim_mode).result.should == expected
+      else
+        ERB.new(@eruby_str, nil, trim_mode).result.should == expected
+      end
     end
   end
 
@@ -61,7 +73,11 @@ END
 </ul>
 END
 
-    ERB.new(input, nil, '-').result.should == expected
+    if RUBY_VERSION >= '2.6'
+      ERB.new(input, trim_mode: '-').result.should == expected
+    else
+      ERB.new(input, nil, '-').result.should == expected
+    end
   end
 
 
@@ -75,23 +91,39 @@ END
 END
 
     lambda {
-      ERB.new(input, nil, '-').result
+      if RUBY_VERSION >= '2.6'
+        ERB.new(input, trim_mode: '-').result
+      else
+        ERB.new(input, nil, '-').result
+      end
     }.should raise_error(SyntaxError)
   end
 
   it "regards lines starting with '%' as '<% ... %>' when trim_mode is '%'" do
     expected = "<ul>\n  <li>1\n  \n  <li>2\n  \n  <li>3\n  \n\n</ul>\n%%\n"
-    ERB.new(@eruby_str2, nil, "%").result.should == expected
+    if RUBY_VERSION >= '2.6'
+      ERB.new(@eruby_str2, trim_mode: "%").result.should == expected
+    else
+      ERB.new(@eruby_str2, nil, "%").result.should == expected
+    end
   end
   it "regards lines starting with '%' as '<% ... %>' and remove \"\\n\" when trim_mode is '%>'" do
     expected = "<ul>\n  <li>1    <li>2    <li>3  </ul>\n%%\n"
-    ERB.new(@eruby_str2, nil, '%>').result.should == expected
+    if RUBY_VERSION >= '2.6'
+      ERB.new(@eruby_str2, trim_mode: '%>').result.should == expected
+    else
+      ERB.new(@eruby_str2, nil, '%>').result.should == expected
+    end
   end
 
 
   it "regard lines starting with '%' as '<% ... %>' and remove \"\\n\" when trim_mode is '%<>'" do
     expected = "<ul>\n  <li>1\n  \n  <li>2\n  \n  <li>3\n  \n</ul>\n%%\n"
-    ERB.new(@eruby_str2, nil, '%<>').result.should == expected
+    if RUBY_VERSION >= '2.6'
+      ERB.new(@eruby_str2, trim_mode: '%<>').result.should == expected
+    else
+      ERB.new(@eruby_str2, nil, '%<>').result.should == expected
+    end
   end
 
 
@@ -106,13 +138,22 @@ END
 %%%
 END
 
-    ERB.new(input, nil, '%-').result.should == expected
+    if RUBY_VERSION >= '2.6'
+      ERB.new(input, trim_mode: '%-').result.should == expected
+    else
+      ERB.new(input, nil, '%-').result.should == expected
+    end
   end
 
   it "changes '_erbout' variable name in the produced source" do
     input = @eruby_str
-    match_erbout = ERB.new(input, nil, nil).src
-    match_buf = ERB.new(input, nil, nil, 'buf').src
+    if RUBY_VERSION >= '2.6'
+      match_erbout = ERB.new(input, trim_mode: nil).src
+      match_buf = ERB.new(input, trim_mode: nil, eoutvar: 'buf').src
+    else
+      match_erbout = ERB.new(input, nil, nil).src
+      match_buf = ERB.new(input, nil, nil, 'buf').src
+    end
     match_erbout.gsub("_erbout", "buf").should == match_buf
   end
 
@@ -124,7 +165,11 @@ END
 <%# end %>
 END
     ERB.new(input).result.should == "\n<b></b>\n\n"
-    ERB.new(input, nil, '<>').result.should == "<b></b>\n"
+    if RUBY_VERSION >= '2.6'
+      ERB.new(input, trim_mode: '<>').result.should == "<b></b>\n"
+    else
+      ERB.new(input, nil, '<>').result.should == "<b></b>\n"
+    end
   end
 
   it "forget local variables defined previous one" do
diff --git a/test/erb/test_erb.rb b/test/erb/test_erb.rb
index 045ce5129b..ffa1fef23d 100644
--- a/test/erb/test_erb.rb
+++ b/test/erb/test_erb.rb
@@ -24,16 +24,22 @@ class TestERB < Test::Unit::TestCase
     assert_match(/\Atest filename:1\b/, e.backtrace[0])
   end
 
+  # [deprecated] This will be removed at Ruby 2.7
   def test_without_filename_with_safe_level
-    erb = ERB.new("<% raise ::TestERB::MyError %>", 1)
+    erb = EnvUtil.suppress_warning do
+      ERB.new("<% raise ::TestERB::MyError %>", 1)
+    end
     e = assert_raise(MyError) {
       erb.result
     }
     assert_match(/\A\(erb\):1\b/, e.backtrace[0])
   end
 
+  # [deprecated] This will be removed at Ruby 2.7
   def test_with_filename_and_safe_level
-    erb = ERB.new("<% raise ::TestERB::MyError %>", 1)
+    erb = EnvUtil.suppress_warning do
+      ERB.new("<% raise ::TestERB::MyError %>", 1)
+    end
     erb.filename = "test filename"
     e = assert_raise(MyError) {
       erb.result
@@ -92,9 +98,12 @@ class TestERBCore < Test::Unit::TestCase
   end
 
   def test_core
-    _test_core(nil)
-    _test_core(0)
-    _test_core(1)
+    # [deprecated] Fix initializer at Ruby 2.7
+    EnvUtil.suppress_warning do
+      _test_core(nil)
+      _test_core(0)
+      _test_core(1)
+    end
   end
 
   def _test_core(safe)
@@ -203,26 +212,26 @@ EOS
   end
 
   def test_trim_line1_with_carriage_return
-    erb = @erb.new("<% 3.times do %>\r\nline\r\n<% end %>\r\n", nil, '>')
+    erb = @erb.new("<% 3.times do %>\r\nline\r\n<% end %>\r\n", trim_mode: '>')
     assert_equal("line\r\n" * 3, erb.result)
 
-    erb = @erb.new("<% 3.times do %>\r\nline\r\n<% end %>\r\n", nil, '%>')
+    erb = @erb.new("<% 3.times do %>\r\nline\r\n<% end %>\r\n", trim_mode: '%>')
     assert_equal("line\r\n" * 3, erb.result)
   end
 
   def test_trim_line2_with_carriage_return
-    erb = @erb.new("<% 3.times do %>\r\nline\r\n<% end %>\r\n", nil, '<>')
+    erb = @erb.new("<% 3.times do %>\r\nline\r\n<% end %>\r\n", trim_mode: '<>')
     assert_equal("line\r\n" * 3, erb.result)
 
-    erb = @erb.new("<% 3.times do %>\r\nline\r\n<% end %>\r\n", nil, '%<>')
+    erb = @erb.new("<% 3.times do %>\r\nline\r\n<% end %>\r\n", trim_mode: '%<>')
     assert_equal("line\r\n" * 3, erb.result)
   end
 
   def test_explicit_trim_line_with_carriage_return
-    erb = @erb.new("<%- 3.times do -%>\r\nline\r\n<%- end -%>\r\n", nil, '-')
+    erb = @erb.new("<%- 3.times do -%>\r\nline\r\n<%- end -%>\r\n", trim_mode: '-')
     assert_equal("line\r\n" * 3, erb.result)
 
-    erb = @erb.new("<%- 3.times do -%>\r\nline\r\n<%- end -%>\r\n", nil, '%-')
+    erb = @erb.new("<%- 3.times do -%>\r\nline\r\n<%- end -%>\r\n", trim_mode: '%-')
     assert_equal("line\r\n" * 3, erb.result)
   end
 
@@ -259,26 +268,26 @@ EOS
 %n = 1
 <%= n%>
 EOS
-    assert_equal("1\n", ERB.new(src, nil, '%').result(binding))
+    assert_equal("1\n", ERB.new(src, trim_mode: '%').result(binding))
 
     src = <<EOS
 <%
 %>
 EOS
     ans = "\n"
-    assert_equal(ans, ERB.new(src, nil, '%').result(binding))
+    assert_equal(ans, ERB.new(src, trim_mode: '%').result(binding))
 
     src = "<%\n%>"
     # ans = "\n"
     ans = ""
-    assert_equal(ans, ERB.new(src, nil, '%').result(binding))
+    assert_equal(ans, ERB.new(src, trim_mode: '%').result(binding))
 
     src = <<EOS
 <%
 n = 1
 %><%= n%>
 EOS
-    assert_equal("1\n", ERB.new(src, nil, '%').result(binding))
+    assert_equal("1\n", ERB.new(src, trim_mode: '%').result(binding))
 
     src = <<EOS
 %n = 1
@@ -294,7 +303,7 @@ EOS
 % %%><%1
 %%
 EOS
-    assert_equal(ans, ERB.new(src, nil, '%').result(binding))
+    assert_equal(ans, ERB.new(src, trim_mode: '%').result(binding))
   end
 
   def test_def_erb_method
@@ -378,7 +387,7 @@ foo
 %% print 'foo'
 
 EOS
-    assert_equal(ans, ERB.new(src, nil, '%').result)
+    assert_equal(ans, ERB.new(src, trim_mode: '%').result)
   end
 
   def test_keep_lineno
@@ -389,7 +398,7 @@ Hello,\s
 % raise("lineno")
 EOS
 
-    erb = ERB.new(src, nil, '%')
+    erb = ERB.new(src, trim_mode: '%')
     e = assert_raise(RuntimeError) {
       erb.result
     }
@@ -407,7 +416,7 @@ EOS
 %>Hello,\s
 World%>
 EOS
-    assert_equal(ans, ERB.new(src, nil, '>').result)
+    assert_equal(ans, ERB.new(src, trim_mode: '>').result)
 
     ans = <<EOS
 %>
@@ -415,7 +424,7 @@ Hello,\s
 
 World%>
 EOS
-    assert_equal(ans, ERB.new(src, nil, '<>').result)
+    assert_equal(ans, ERB.new(src, trim_mode: '<>').result)
 
     ans = <<EOS
 %>
@@ -440,13 +449,13 @@ EOS
     }
     assert_match(/\A\(erb\):5\b/, e.backtrace[0].to_s)
 
-    erb = ERB.new(src, nil, '>')
+    erb = ERB.new(src, trim_mode: '>')
     e = assert_raise(RuntimeError) {
       erb.result
     }
     assert_match(/\A\(erb\):5\b/, e.backtrace[0].to_s)
 
-    erb = ERB.new(src, nil, '<>')
+    erb = ERB.new(src, trim_mode: '<>')
     e = assert_raise(RuntimeError) {
       erb.result
     }
@@ -460,13 +469,13 @@ EOS
 <% raise("lineno") %>
 EOS
 
-    erb = ERB.new(src, nil, '-')
+    erb = ERB.new(src, trim_mode: '-')
     e = assert_raise(RuntimeError) {
       erb.result
     }
     assert_match(/\A\(erb\):5\b/, e.backtrace[0].to_s)
 
-    erb = ERB.new(src, nil, '%-')
+    erb = ERB.new(src, trim_mode: '%-')
     e = assert_raise(RuntimeError) {
       erb.result
     }
@@ -502,8 +511,8 @@ NotSkip  NotSkip
    * WORLD
 KeepNewLine \s
 EOS
-   assert_equal(ans, ERB.new(src, nil, '-').result)
-   assert_equal(ans, ERB.new(src, nil, '-%').result)
+   assert_equal(ans, ERB.new(src, trim_mode: '-').result)
+   assert_equal(ans, ERB.new(src, trim_mode: '-%').result)
   end
 
   def test_url_encode
@@ -519,7 +528,7 @@ EOS
   end
 
   def test_percent_after_etag
-    assert_equal("1%", @erb.new("<%= 1 %>%", nil, "%").result)
+    assert_equal("1%", @erb.new("<%= 1 %>%", trim_mode: "%").result)
   end
 
   def test_token_extension
@@ -629,6 +638,27 @@ EOS
       @erb.new("<% # comment %>\n").result
     end
   end
+
+  # These interfaces will be removed at Ruby 2.7.
+  def test_deprecated_interface_warnings
+    [nil, 0, 1, 2].each do |safe|
+      assert_warning(/2nd argument of ERB.new is deprecated/) do
+        ERB.new('', safe)
+      end
+    end
+
+    [nil, '', '%', '%<>'].each do |trim|
+      assert_warning(/3rd argument of ERB.new is deprecated/) do
+        ERB.new('', nil, trim)
+      end
+    end
+
+    [nil, '_erbout', '_hamlout'].each do |eoutvar|
+      assert_warning(/4th argument of ERB.new is deprecated/) do
+        ERB.new('', nil, nil, eoutvar)
+      end
+    end
+  end
 end
 
 class TestERBCoreWOStrScan < TestERBCore
diff --git a/test/erb/test_erb_command.rb b/test/erb/test_erb_command.rb
index 7e2b874632..ac87b07740 100644
--- a/test/erb/test_erb_command.rb
+++ b/test/erb/test_erb_command.rb
@@ -15,4 +15,16 @@ class TestErbCommand < Test::Unit::TestCase
                        File.expand_path("../../../bin/erb", __FILE__)],
                       "<%=''.encoding.to_s%>", ["UTF-8"])
   end
+
+  # These interfaces will be removed at Ruby 2.7.
+  def test_deprecated_option
+    warnings = [
+      "warning: -S option of erb command is deprecated. Please do not use this.",
+      "warning: Passing safe_level with the 2nd argument of ERB.new is deprecated. Do not use it, and specify other arguments as keyword arguments.",
+    ]
+    assert_in_out_err(["-w",
+                       File.expand_path("../../../bin/erb", __FILE__),
+                       "-S", "0"],
+                      "hoge", ["hoge"], warnings)
+  end
 end
diff --git a/tool/generic_erb.rb b/tool/generic_erb.rb
index c9986c7284..83c569b55b 100644
--- a/tool/generic_erb.rb
+++ b/tool/generic_erb.rb
@@ -34,7 +34,11 @@ unchanged = color.pass("unchanged")
 updated = color.fail("updated")
 
 result = templates.map do |template|
-  erb = ERB.new(File.read(template), nil, '%-')
+  if RUBY_VERSION >= '2.6'
+    erb = ERB.new(File.read(template), trim_mode: '%-')
+  else
+    erb = ERB.new(File.read(template), nil, '%-')
+  end
   erb.filename = template
   source ? erb.src : proc{erb.result(binding)}.call
 end
diff --git a/tool/ruby_vm/helpers/dumper.rb b/tool/ruby_vm/helpers/dumper.rb
index b622b898b9..ec7871dbea 100644
--- a/tool/ruby_vm/helpers/dumper.rb
+++ b/tool/ruby_vm/helpers/dumper.rb
@@ -32,7 +32,11 @@ class RubyVM::Dumper
   rescue Errno::ENOENT
     raise "don't know how to generate #{path}"
   else
-    erb = ERB.new src, nil, '%-'
+    if RUBY_VERSION >= '2.6'
+      erb = ERB.new(src, trim_mode: '%-')
+    else
+      erb = ERB.new(src, nil, '%-')
+    end
     erb.filename = path.realpath.to_path
     return erb
   end
diff --git a/tool/transcode-tblgen.rb b/tool/transcode-tblgen.rb
index f43627b781..6a896ad392 100644
--- a/tool/transcode-tblgen.rb
+++ b/tool/transcode-tblgen.rb
@@ -1078,7 +1078,11 @@ if __FILE__ == $0
   end
 
   libs1 = $".dup
-  erb = ERB.new(src, nil, '%')
+  if RUBY_VERSION >= '2.6'
+    erb = ERB.new(src, trim_mode: '%')
+  else
+    erb = ERB.new(src, nil, '%')
+  end
   erb.filename = arg
   erb_result = erb.result(binding)
   libs2 = $".dup