Fix bad NameError raised using sendforward instruction through vcall

If you called a VCALL method and the method takes forwarding arguments
and then you forward those arguments along using the sendforward
instruction, the method_missing class was wrongly chosen as NameError
instead of NoMethodError. This is because the VM looked at the CallInfo
of the vcall and determined it needed to raise NameError. Now we detect
that case and raise NoMethodError.

[Backport #21535]

Author: luke-gruber

test/ruby/test_nomethod_error.rb

@@ -106,4 +106,32 @@ def name
 
     assert_match(/undefined method.+this_method_does_not_exist.+for.+Module/, err.to_s)
   end
+
+  def test_send_forward_raises
+    t = EnvUtil.labeled_class("Test") do
+      def foo(...)
+        forward(...)
+      end
+    end
+    obj = t.new
+    assert_raise(NoMethodError) do
+      obj.foo
+    end
+  end
+
+  # [Bug #21535]
+  def test_send_forward_raises_when_called_through_vcall
+    t = EnvUtil.labeled_class("Test") do
+      def foo(...)
+        forward(...)
+      end
+      def foo_indirect
+        foo # vcall
+      end
+    end
+    obj = t.new
+    assert_raise(NoMethodError) do
+      obj.foo_indirect
+    end
+  end
 end

vm_insnhelper.c

@@ -4185,7 +4185,7 @@ static enum method_missing_reason
 ci_missing_reason(const struct rb_callinfo *ci)
 {
     enum method_missing_reason stat = MISSING_NOENTRY;
-    if (vm_ci_flag(ci) & VM_CALL_VCALL) stat |= MISSING_VCALL;
+    if (vm_ci_flag(ci) & VM_CALL_VCALL && !(vm_ci_flag(ci) & VM_CALL_FORWARDING)) stat |= MISSING_VCALL;
     if (vm_ci_flag(ci) & VM_CALL_FCALL) stat |= MISSING_FCALL;
     if (vm_ci_flag(ci) & VM_CALL_SUPER) stat |= MISSING_SUPER;
     return stat;