error in reduce(&:merge)

[pvcresin]

Repro

• Ruby version: ruby 3.3.3 (2024-06-12 revision f1c7b6f435) [arm64-darwin23]
• Steep version: 1.8.1
• Passing multiple args through Symbol#to_proc is not supported yet

# sample.rbs
class Sample
end

# sample.rb
class Sample
  def ng
    merged1 = [{ a: 1 }, { b: 2 }].reduce(&:merge)
    p merged1 # => {:a=>1, :b=>2}
  end

  def ok
    merged2 = [{ a: 1 }, { b: 2 }].reduce { |acc, hash| acc.merge(hash) }
    p merged2 # => {:a=>1, :b=>2}
  end
end

Sample.new.ng
Sample.new.ok

$ ruby lib/sample.rb
{:a=>1, :b=>2}
{:a=>1, :b=>2}

$ bundle exec steep check

$ bundle exec steep check
# Type checking files:

...............................................................................2024-10-24 13:18:15.548: ERROR: [Steep 1.8.1] [typecheck:typecheck@0] [background] [#typecheck_source(path=lib/sample.rb)] [#type_check_file(lib/sample.rb@lib)] [synthesize:(1:1)] [synthesize:(1:1)] [synthesize:(2:3)] [synthesize:(2:3)] [synthesize:(3:5)] [synthesize:(3:5)] [synthesize:(3:14)] [[A] (A) { (A, ::Hash[::Symbol, ::Integer]) -> A } -> A] [synthesize:(3:42)] Passing multiple args through Symbol#to_proc is not supported yet
2024-10-24 13:18:15.550: ERROR: [Steep 1.8.1] [typecheck:typecheck@0] [background] [#typecheck_source(path=lib/sample.rb)] [#type_check_file(lib/sample.rb@lib)] [synthesize:(1:1)] [synthesize:(1:1)] [synthesize:(2:3)] [synthesize:(2:3)] [synthesize:(3:5)] [synthesize:(3:5)] [synthesize:(3:14)] [() { (::Hash[::Symbol, ::Integer], ::Hash[::Symbol, ::Integer]) -> ::Hash[::Symbol, ::Integer] } -> ::Hash[::Symbol, ::Integer]] [synthesize:(3:42)] Passing multiple args through Symbol#to_proc is not supported yet
......

No type error detected. 🫖