YJIT: Detect and reject `send(:alias_for_send, :foo)`

Previously, YJIT failed to put the stack into the correct shape when
`BasicObject#send` calls an alias method for the send method itself.
This can manifest as strange `NoMethodError`s in the final non-send
receiver, as [seen][1] with the kt-paperclip gem. I also found a case
where it makes YJIT fail the stack size assertion while compiling
`leave`.

YJIT's `BasicObject#__send__` implementation already rejects sends to
`send`, but didn't detect sends to aliases of `send`. Adjust the
detection and reject these cases.

Fixes [Bug #19464]

[1]: https://github.com/Shopify/yjit/issues/306

1 files changed, 20 insertions, 0 deletions

diff --git a/test/ruby/test_yjit.rb b/test/ruby/test_yjit.rb
index 7f0f691320..3f7704116f 100644
--- a/test/ruby/test_yjit.rb
+++ b/test/ruby/test_yjit.rb
@@ -1196,6 +1196,26 @@ class TestYJIT < Test::Unit::TestCase
     RUBY
   end
 
+  def test_nested_send
+    #[Bug #19464]
+    assert_compiles(<<~RUBY, result: [:ok, :ok])
+      klass = Class.new do
+        class << self
+          alias_method :my_send, :send
+
+          def bar = :ok
+
+          def foo = bar
+        end
+      end
+
+      with_break = -> { break klass.send(:my_send, :foo) }
+      wo_break = -> { klass.send(:my_send, :foo) }
+
+      [with_break[], wo_break[]]
+    RUBY
+  end
+
   private
 
   def code_gc_helpers