[Bug #20423] Disallow anonymous block within argument forwarding

parse.y

@@ -4263,7 +4263,7 @@ block_arg	: tAMPER arg_value
                     }
                 | tAMPER
                     {
-                        forwarding_arg_check(p, idFWD_BLOCK, 0, "block");
+                        forwarding_arg_check(p, idFWD_BLOCK, idFWD_ALL, "block");
                         $$ = NEW_BLOCK_PASS(NEW_LVAR(idFWD_BLOCK, &@1), &@$);
                     /*% ripper: Qnil %*/
                     }

prism/prism.c

@@ -13486,7 +13486,6 @@ parse_parameters(
                     update_parameter_state(parser, &parser->current, &order);
                     parser_lex(parser);
 
-                    parser->current_scope->parameters |= PM_SCOPE_PARAMETERS_FORWARDING_BLOCK;
                     parser->current_scope->parameters |= PM_SCOPE_PARAMETERS_FORWARDING_ALL;
 
                     pm_forwarding_parameter_node_t *param = pm_forwarding_parameter_node_create(parser, &parser->previous);

test/prism/fixtures/methods.txt

@@ -175,7 +175,7 @@ def f x:!a; end
 def foo x:%(xx); end
 
 def foo(...)
-  bar(&)
+  bar(...)
 end
 
 def foo(bar = (def baz(bar) = bar; 1)) = 2

test/prism/snapshots/methods.txt

@@ -1908,21 +1908,22 @@
         │   │   │   @ ForwardingParameterNode (location: (177,8)-(177,11))
         │   │   └── block: ∅
         │   ├── body:
-        │   │   @ StatementsNode (location: (178,2)-(178,7))
+        │   │   @ StatementsNode (location: (178,2)-(178,10))
         │   │   └── body: (length: 1)
-        │   │       └── @ CallNode (location: (178,2)-(178,7))
+        │   │       └── @ CallNode (location: (178,2)-(178,10))
         │   │           ├── flags: ignore_visibility
         │   │           ├── receiver: ∅
         │   │           ├── call_operator_loc: ∅
         │   │           ├── name: :bar
         │   │           ├── message_loc: (178,2)-(178,5) = "bar"
         │   │           ├── opening_loc: (178,5)-(178,6) = "("
-        │   │           ├── arguments: ∅
-        │   │           ├── closing_loc: (178,7)-(178,8) = ")"
-        │   │           └── block:
-        │   │               @ BlockArgumentNode (location: (178,6)-(178,7))
-        │   │               ├── expression: ∅
-        │   │               └── operator_loc: (178,6)-(178,7) = "&"
+        │   │           ├── arguments:
+        │   │           │   @ ArgumentsNode (location: (178,6)-(178,9))
+        │   │           │   ├── flags: ∅
+        │   │           │   └── arguments: (length: 1)
+        │   │           │       └── @ ForwardingArgumentsNode (location: (178,6)-(178,9))
+        │   │           ├── closing_loc: (178,9)-(178,10) = ")"
+        │   │           └── block: ∅
         │   ├── locals: []
         │   ├── def_keyword_loc: (177,0)-(177,3) = "def"
         │   ├── operator_loc: ∅

test/ruby/test_compile_prism.rb

@@ -1839,15 +1839,6 @@ end
 
         o.bar { :ok }
       RUBY
-
-      # Test anonymous block forwarding from argument forwarding
-      assert_prism_eval(<<~RUBY)
-        o = Object.new
-        def o.foo = yield
-        def o.bar(...) = foo(&)
-
-        o.bar { :ok }
-      RUBY
     end
 
     def test_BlockLocalVariableNode

test/ruby/test_syntax.rb

@@ -190,6 +190,7 @@ class TestSyntax < Test::Unit::TestCase
     assert_syntax_error("def f(...); g(0, *); end", /no anonymous rest parameter/)
     assert_syntax_error("def f(...); g(**); end", /no anonymous keyword rest parameter/)
     assert_syntax_error("def f(...); g(x: 1, **); end", /no anonymous keyword rest parameter/)
+    assert_syntax_error("def f(...); g(&); end", /no anonymous block parameter/)
   end
 
   def test_newline_in_block_parameters