Syntax check of `yield` in the parser

4 files changed, 43 insertions, 5 deletions

diff --git a/parse.y b/parse.y
index 7570ba050f..e9ebfebf61 100644
--- a/parse.y
+++ b/parse.y
@@ -2697,7 +2697,7 @@ command		: fcall command_args       %prec tLOWEST
                     /*% %*/
                     /*% ripper: super!($2) %*/
                     }
-                | keyword_yield command_args
+                | k_yield command_args
                     {
                     /*%%%*/
                         $$ = new_yield(p, $2, &@$);
@@ -3797,21 +3797,21 @@ primary		: literal
                     /*% %*/
                     /*% ripper: return0! %*/
                     }
-                | keyword_yield '(' call_args rparen
+                | k_yield '(' call_args rparen
                     {
                     /*%%%*/
                         $$ = new_yield(p, $3, &@$);
                     /*% %*/
                     /*% ripper: yield!(paren!($3)) %*/
                     }
-                | keyword_yield '(' rparen
+                | k_yield '(' rparen
                     {
                     /*%%%*/
                         $$ = NEW_YIELD(0, &@$);
                     /*% %*/
                     /*% ripper: yield!(paren!(args_new!)) %*/
                     }
-                | keyword_yield
+                | k_yield
                     {
                     /*%%%*/
                         $$ = NEW_YIELD(0, &@$);
@@ -4294,6 +4294,13 @@ k_return	: keyword_return
                     }
                 ;
 
+k_yield 	: keyword_yield
+                    {
+                        if (!p->ctxt.in_defined && !p->ctxt.in_def && !dyna_in_block(p))
+                            yyerror1(&@1, "Invalid yield");
+                    }
+                ;
+
 then		: term
                 | keyword_then
                 | term keyword_then
diff --git a/test/prism/parse_test.rb b/test/prism/parse_test.rb
index 65128bf5a7..3c0d584a12 100644
--- a/test/prism/parse_test.rb
+++ b/test/prism/parse_test.rb
@@ -89,7 +89,7 @@ module Prism
           src = source
 
           case relative
-          when /break|next|redo|if|unless|rescue|control|keywords|retry/
+          when /break|next|redo|if|unless|rescue|control|keywords|retry|yield|\/args_assocs/
             # Uncaught syntax errors: Invalid break, Invalid next
             src = "->do\nrescue\n#{src}\nend"
             ripper_should_match = false
diff --git a/test/ruby/test_ast.rb b/test/ruby/test_ast.rb
index 70ebd22a98..76fd2b3783 100644
--- a/test/ruby/test_ast.rb
+++ b/test/ruby/test_ast.rb
@@ -285,6 +285,34 @@ class TestAst < Test::Unit::TestCase
     assert_parse("begin rescue; END {defined? retry}; end")
   end
 
+  def test_invalid_yield
+    msg = /Invalid yield/
+    assert_invalid_parse(msg, "yield")
+    assert_invalid_parse(msg, "class C; yield; end")
+    assert_invalid_parse(msg, "BEGIN {yield}")
+    assert_invalid_parse(msg, "END {yield}")
+
+    assert_invalid_parse(msg, "yield true")
+    assert_invalid_parse(msg, "class C; yield true; end")
+    assert_invalid_parse(msg, "BEGIN {yield true}")
+    assert_invalid_parse(msg, "END {yield true}")
+
+    assert_parse("!defined?(yield)")
+    assert_parse("class C; defined?(yield); end")
+    assert_parse("BEGIN {defined?(yield)}")
+    assert_parse("END {defined?(yield)}")
+
+    assert_parse("!defined?(yield true)")
+    assert_parse("class C; defined?(yield true); end")
+    assert_parse("BEGIN {defined?(yield true)}")
+    assert_parse("END {defined?(yield true)}")
+
+    assert_parse("!defined? yield")
+    assert_parse("class C; defined? yield; end")
+    assert_parse("BEGIN {defined? yield}")
+    assert_parse("END {defined? yield}")
+  end
+
   def test_node_id_for_location
     exception = begin
                   raise
diff --git a/test/ruby/test_rubyoptions.rb b/test/ruby/test_rubyoptions.rb
index a2f738d9a5..b2e2e7bb6c 100644
--- a/test/ruby/test_rubyoptions.rb
+++ b/test/ruby/test_rubyoptions.rb
@@ -373,14 +373,17 @@ class TestRubyOptions < Test::Unit::TestCase
     assert_in_out_err(%w(-cw -e next), "", [], ["-e:1: Invalid next", :*])
     assert_in_out_err(%w(-cw -e redo), "", [], ["-e:1: Invalid redo", :*])
     assert_in_out_err(%w(-cw -e retry), "", [], ["-e:1: Invalid retry", :*])
+    assert_in_out_err(%w(-cw -e yield), "", [], ["-e:1: Invalid yield", :*])
     assert_in_out_err(%w(-cw -e begin -e break -e end), "", [], ["-e:2: Invalid break", :*])
     assert_in_out_err(%w(-cw -e begin -e next -e end), "", [], ["-e:2: Invalid next", :*])
     assert_in_out_err(%w(-cw -e begin -e redo -e end), "", [], ["-e:2: Invalid redo", :*])
     assert_in_out_err(%w(-cw -e begin -e retry -e end), "", [], ["-e:2: Invalid retry", :*])
+    assert_in_out_err(%w(-cw -e begin -e yield -e end), "", [], ["-e:2: Invalid yield", :*])
     assert_in_out_err(%w(-cw -e !defined?(break)), "", ["Syntax OK"], [])
     assert_in_out_err(%w(-cw -e !defined?(next)), "", ["Syntax OK"], [])
     assert_in_out_err(%w(-cw -e !defined?(redo)), "", ["Syntax OK"], [])
     assert_in_out_err(%w(-cw -e !defined?(retry)), "", ["Syntax OK"], [])
+    assert_in_out_err(%w(-cw -e !defined?(yield)), "", ["Syntax OK"], [])
     assert_in_out_err(%w(-n -cw -e break), "", ["Syntax OK"], [])
     assert_in_out_err(%w(-n -cw -e next), "", ["Syntax OK"], [])
     assert_in_out_err(%w(-n -cw -e redo), "", ["Syntax OK"], [])