nobu	2018-03-23 09:40:08 +0900 (Fri, 23 Mar 2018)

  New Revision: 62901

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=62901

  Log:
    parse.y: else without rescue
    
    * parse.y (bodystmt): [EXPERIMENTAL] make `else` without `rescue`
      a syntax error.  [DevelopersMeeting20180315Japan]
    
      https://bugs.ruby-lang.org/projects/ruby/wiki/DevelopersMeeting20180315Japan
      https://docs.google.com/document/d/1RT0ijSo8uJ4Awn3CEvuYkjH0TVeXSYgeAFNmVGYC3ak/edit#
      > * do-else-end
      >   https://twitter.com/joker1007/status/974173396006129664
      >   https://twitter.com/joker1007/status/974173641347756032
      >   https://twitter.com/joker1007/status/974176512554369027
      >   Will be SyntaxError in 2.6-preview2
      >   All of begin/do/def (experimental)

  Modified files:
    trunk/NEWS
    trunk/parse.y
    trunk/spec/ruby/language/rescue_spec.rb
    trunk/test/ruby/test_parse.rb
Index: NEWS
===================================================================
--- NEWS	(revision 62900)
+++ NEWS	(revision 62901)
@@ -18,6 +18,8 @@ with all sufficient information, see the https://github.com/ruby/ruby/blob/trunk/NEWS#L18
 
 * refinements take place at block passing.  [Feature #14223]
 
+* `else` without `rescue` is now causes a syntax error.  [EXPERIMENTAL]
+
 === Core classes updates (outstanding ones only)
 
 * Array
Index: test/ruby/test_parse.rb
===================================================================
--- test/ruby/test_parse.rb	(revision 62900)
+++ test/ruby/test_parse.rb	(revision 62901)
@@ -14,13 +14,12 @@ class TestParse < Test::Unit::TestCase https://github.com/ruby/ruby/blob/trunk/test/ruby/test_parse.rb#L14
   end
 
   def test_else_without_rescue
-    x = eval <<-END, nil, __FILE__, __LINE__+1
+    assert_syntax_error(<<-END, /else without rescue/)
       begin
       else
         42
       end
     END
-    assert_equal(42, x)
   end
 
   def test_alias_backref
Index: parse.y
===================================================================
--- parse.y	(revision 62900)
+++ parse.y	(revision 62901)
@@ -1000,7 +1000,7 @@ bodystmt	: compstmt https://github.com/ruby/ruby/blob/trunk/parse.y#L1000
 			    $$ = NEW_RESCUE($1, $2, $3, &@$);
 			}
 			else if ($3) {
-			    rb_warn0("else without rescue is useless");
+			    compile_error(p, "else without rescue is useless");
 			    $$ = block_append(p, $$, $3);
 			}
 			if ($4) {
Index: spec/ruby/language/rescue_spec.rb
===================================================================
--- spec/ruby/language/rescue_spec.rb	(revision 62900)
+++ spec/ruby/language/rescue_spec.rb	(revision 62901)
@@ -195,18 +195,26 @@ describe "The rescue keyword" do https://github.com/ruby/ruby/blob/trunk/spec/ruby/language/rescue_spec.rb#L195
     ScratchPad.recorded.should == [:one, :else_ran, :ensure_ran, :outside_begin]
   end
 
-  it "will execute an else block even without rescue and ensure" do
-    lambda {
-      eval <<-ruby
+  else_without_rescue = lambda {
+    eval <<-ruby
         begin
           ScratchPad << :begin
         else
           ScratchPad << :else
         end
       ruby
-    }.should complain(/else without rescue is useless/)
+  }
 
-    ScratchPad.recorded.should == [:begin, :else]
+  ruby_version_is ""..."2.6" do
+    it "will execute an else block even without rescue and ensure" do
+      else_without_rescue.should complain(/else without rescue is useless/)
+
+      ScratchPad.recorded.should == [:begin, :else]
+    end
+  end
+
+  ruby_version_is "2.6" do
+    else_without_rescue.should raise_error(SyntaxError)
   end
 
   it "will not execute an else block if an exception was raised" do

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