Bug #15753: unknown keyword when passing an hash to a method that accepts a default argument and a named argument

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 2.7.0dev (2019-03-18 trunk 67296) [x86_64-darwin17] / ruby 2.6.2p47 (2019-03-13 revision 67232) [x86_64-darwin17]
• Backport: 2.4: UNKNOWN, 2.5: UNKNOWN, 2.6: UNKNOWN

[localhostdotdev (localhost .dev)]

e.g.

>> def a(b = {}, c: 1); p [b, c]; end; a(a: 1)
Traceback (most recent call last):
        3: from (irb):3
        2: from (irb):3:in `rescue in irb_binding'
        1: from (irb):3:in `a'
ArgumentError (unknown keyword: a)

Prettier version:

def do_something(thing = {}, force: true)
  # doing things
end

do_something({ user: { id: 1 } })
# => ArgumentError (unknown keyword: user)

Tested on ruby-head from ~1 month ago and ruby 2.6.2

[jeremyevans0 (Jeremy Evans)]

I believe this is the same issue as #12717. We are trying to address this issue in #14183.

[jeremyevans0 (Jeremy Evans)]

• Related to Feature #14183: "Real" keyword argument added

[jeremyevans0 (Jeremy Evans)]

• Status changed from Open to Closed

The first example should fail, because you are passing an unsupported keyword to a method that accepts a keyword.

With the acceptance of #14183, the second example now submits a warning:

do_something({ user: { id: 1 } })
# (irb):85: warning: The last argument is used as the keyword parameter
# (irb):82: warning: for `do_something' defined here
# ArgumentError (unknown keyword: :user)

In Ruby 3, the second example will pass the hash as the first argument. To get the Ruby 3 behavior with the master branch:

do_something({ user: { id: 1 } }, **(;{}))
# => nil