Possible solution to the alias puzzle, with benchmarks

1 - overridable_alias.rb

require 'active_support/core_ext/array/wrap'

module OverridableAlias
  def overridable_alias(name, aliases:, &block)
    define_method(name) do
      method = method(name)

      if method.super_method
        send(name) # faster than method.call
      else
        yield
      end
    end

    Array.wrap(aliases).each do |a|
      alias_method a, name
    end
  end
end

2 - alias.rb

class A
  extend OverridableAlias

  overridable_alias(:foo, aliases: [:bar, :baz]) do
    'hello'
  end
end

class B < A
  def foo
    'bye'
  end
end

class C < A

end

class D
  def foo
    'hello'
  end

  alias_method :bar, :foo
end

class E < D
  def foo
    'bye'
  end

  alias_method :bar, :foo
end

3 - benchmark.rb

require 'benchmark/ips'

a = A.new
b = B.new
c = C.new
d = D.new
e = E.new

Benchmark.ips do |x|
  x.report("a.bar") { a.bar }
  x.report("b.bar") { b.bar }
  x.report("c.bar") { c.bar }
  x.report("d.bar") { d.bar }
  x.report("e.bar") { e.bar }
  x.compare!
end

Warming up --------------------------------------
               a.bar   122.867k i/100ms
               b.bar    89.096k i/100ms
               c.bar   122.991k i/100ms
               d.bar   248.042k i/100ms
               e.bar   248.293k i/100ms
Calculating -------------------------------------
               a.bar      2.029M (±10.3%) i/s -     10.075M in   5.028884s
               b.bar      1.325M (± 5.1%) i/s -      6.682M in   5.055119s
               c.bar      2.067M (± 5.1%) i/s -     10.331M in   5.013844s
               d.bar      8.198M (± 5.1%) i/s -     40.927M in   5.005289s
               e.bar      8.521M (± 6.7%) i/s -     42.458M in   5.007338s

Comparison:
               e.bar:  8520938.6 i/s
               d.bar:  8198143.6 i/s - same-ish: difference falls within error
               c.bar:  2066677.3 i/s - 4.12x  slower
               a.bar:  2028980.8 i/s - 4.20x  slower
               b.bar:  1325251.7 i/s - 6.43x  slower