From a9f096183170810ac6ce32b20d7810d11a51b5f5 Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Sat, 23 Dec 2023 18:07:37 +0900
Subject: [PATCH] [Feature #19370] Prohibit nesting anonymous parameter
 forwarding

---
 parse.y                  | 6 ++++++
 test/ruby/test_syntax.rb | 7 +++++++
 2 files changed, 13 insertions(+)

diff --git a/parse.y b/parse.y
index 75b7151e60197c..f8e21dc9a3c1d8 100644
--- a/parse.y
+++ b/parse.y
@@ -15009,6 +15009,8 @@ add_forwarding_args(struct parser_params *p)
 static void
 forwarding_arg_check(struct parser_params *p, ID arg, ID all, const char *var)
 {
+    bool conflict = false;
+
     struct vtable *vars, *args;
 
     vars = p->lvtbl->vars;
@@ -15017,6 +15019,7 @@ forwarding_arg_check(struct parser_params *p, ID arg, ID all, const char *var)
     while (vars && !DVARS_TERMINAL_P(vars->prev)) {
         vars = vars->prev;
         args = args->prev;
+        conflict |= (vtable_included(args, arg) && !(all && vtable_included(args, all)));
     }
 
     bool found = false;
@@ -15032,6 +15035,9 @@ forwarding_arg_check(struct parser_params *p, ID arg, ID all, const char *var)
     if (!found) {
         compile_error(p, "no anonymous %s parameter", var);
     }
+    else if (conflict) {
+        compile_error(p, "anonymous %s parameter is also used within block", var);
+    }
 }
 
 #ifndef RIPPER
diff --git a/test/ruby/test_syntax.rb b/test/ruby/test_syntax.rb
index 7bbb14e3239ae8..33fcc6a1e024aa 100644
--- a/test/ruby/test_syntax.rb
+++ b/test/ruby/test_syntax.rb
@@ -76,6 +76,7 @@ def test_script_lines_encoding
 
   def test_anonymous_block_forwarding
     assert_syntax_error("def b; c(&); end", /no anonymous block parameter/)
+    assert_syntax_error("def b(&) ->(&) {c(&)} end", /anonymous block parameter is also used/)
     assert_separately([], "#{<<-"begin;"}\n#{<<-'end;'}")
     begin;
       def b(&); c(&) end
@@ -143,6 +144,9 @@ def all_kwrest(arg1, arg2, *rest, post1, post2, kw1: 1, kw2: 2, okw1:, okw2:, **
   def test_anonymous_rest_forwarding
     assert_syntax_error("def b; c(*); end", /no anonymous rest parameter/)
     assert_syntax_error("def b; c(1, *); end", /no anonymous rest parameter/)
+    assert_syntax_error("def b(*) ->(*) {c(*)} end", /anonymous rest parameter is also used/)
+    assert_syntax_error("def b(a, *) ->(*) {c(1, *)} end", /anonymous rest parameter is also used/)
+    assert_syntax_error("def b(*) ->(a, *) {c(*)} end", /anonymous rest parameter is also used/)
     assert_separately([], "#{<<-"begin;"}\n#{<<-'end;'}")
     begin;
       def b(*); c(*) end
@@ -156,6 +160,9 @@ def d(*); b(*, *) end
   def test_anonymous_keyword_rest_forwarding
     assert_syntax_error("def b; c(**); end", /no anonymous keyword rest parameter/)
     assert_syntax_error("def b; c(k: 1, **); end", /no anonymous keyword rest parameter/)
+    assert_syntax_error("def b(**) ->(**) {c(**)} end", /anonymous keyword rest parameter is also used/)
+    assert_syntax_error("def b(k:, **) ->(**) {c(k: 1, **)} end", /anonymous keyword rest parameter is also used/)
+    assert_syntax_error("def b(**) ->(k:, **) {c(**)} end", /anonymous keyword rest parameter is also used/)
     assert_separately([], "#{<<-"begin;"}\n#{<<-'end;'}")
     begin;
       def b(**); c(**) end