Ruby::MethodDefinitionMissing with attr_reader

[lloeki]

• attr_reader foo: untyped in RBS defines the signature for the method #foo as would def foo: () -> untyped
• with Steep::Diagnostic::Ruby::MethodDefinitionMissing Steep expects the method #foo from the above
• attr_reader in Ruby defines the method #foo yet Steep can't find it, even though both .rb and .rbsuseattr_reader` semantics

Expected result:

• attr_reader foo: untyped should be able to find attr_reader-defined methods
• Arguably def foo: () -> untyped + @foo: untyped should also work with and find attr_reader :foo
• Same for attr_writer and attr_accessor and #foo=

Actual result:

# foo.rb
class Foo
  attr_reader :foo
end

# foo.rbs
class Foo
  attr_reader foo: untyped
end

# Steepfile
target :lib do
  configure_code_diagnostics do |hash|
    hash[Steep::Diagnostic::Ruby::MethodDefinitionMissing] = :error
  end

  check '.'
  signature '.'
end

$ bundle exec steep check foo.rb
foo.rb:1:6: [error] Cannot find implementation of method `::Foo#foo`
│ Diagnostic ID: Ruby::MethodDefinitionMissing
│
└ class Foo

[lloeki]

Attempted a fix in #1037, probably not a very good one.

[lloeki]

Apparently the solution (as of 1.6.0) is to use @dynamic:

# foo.rb
class Foo
  # @dynamic foo
  attr_reader :foo
end

Which feels very redundant given that RBS's attr_reader already knows that.