Bug #21196: Ruby 3.4 ignores visibility when passing arguments using `...`

• Status: Closed
• Assignee: tenderlovemaking (Aaron Patterson)
• Target version: -
• ruby -v: ruby 3.4.2 (2025-02-15 revision d2930f8e7a) +PRISM [x86_64-linux]
• Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: REQUIRED

[toy (Ivan Kuchin)]

If method is passing arguments using ..., then receiver visibility gets ignored if once called without receiver:

class A
private

  def foo = :foo
  def bar = :bar
end

class B
  def initialize(o)
    @o = o
  end

  def foo(...) = @o.foo(...)
  def bar = @o.bar

  def internal_foo = foo
  def internal_bar = bar
end

def try
  p yield
rescue => e
  p e
end

If foo is called first without receiver through internal_foo:

b = B.new(A.new)

try{ b.internal_foo }
try{ b.internal_bar }
try{ b.foo }
try{ b.bar }

Visibility of A#foo gets ignored:

ruby 3.4.2 (2025-02-15 revision d2930f8e7a) +PRISM [x86_64-linux]
:foo
#<NoMethodError: private method 'bar' called for an instance of A>
:foo
#<NoMethodError: private method 'bar' called for an instance of A>

ruby 3.3.7 (2025-01-15 revision be31f993d7) [x86_64-linux]
#<NoMethodError: private method `foo' called for an instance of A>
#<NoMethodError: private method `bar' called for an instance of A>
#<NoMethodError: private method `foo' called for an instance of A>
#<NoMethodError: private method `bar' called for an instance of A>

If internal_foo is not called before foo:

b = B.new(A.new)

try{ b.foo }
try{ b.bar }

Visibility of A#foo gets checked:

ruby 3.4.2 (2025-02-15 revision d2930f8e7a) +PRISM [x86_64-linux]
#<NoMethodError: private method 'foo' called for an instance of A>
#<NoMethodError: private method 'bar' called for an instance of A>

ruby 3.3.7 (2025-01-15 revision be31f993d7) [x86_64-linux]
#<NoMethodError: private method `foo' called for an instance of A>
#<NoMethodError: private method `bar' called for an instance of A>

[tenderlovemaking (Aaron Patterson)]

• Assignee set to tenderlovemaking (Aaron Patterson)
• Backport changed from 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN to 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: REQUIRED

[tenderlovemaking (Aaron Patterson)]

I've sent a PR with a fix, but I can't seem to merge it right now. I will get it merged as soon as possible.

[tenderlovemaking (Aaron Patterson)]

• Status changed from Open to Closed

Applied in changeset git|595040ba271175e18c8461a926c34903742788de.

---

FCALL shouldn't be forwarded from caller

When we forward an FCALL (a method call with an implicit self), we
shouldn't forward the FCALL flag because it ignores method visibility
checks. This patch removes the FCALL flag from callers.

[Bug #21196]

[tenderlovemaking (Aaron Patterson)]

• Has duplicate Bug #21125: Kernel is called first added