Issue #8463 has been reported by marcandre (Marc-Andre Lafortune).

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Bug #8463: Proc auto-splat bug with named arguments
https://bugs.ruby-lang.org/issues/8463

Author: marcandre (Marc-Andre Lafortune)
Status: Open
Priority: High
Assignee: nobu (Nobuyoshi Nakada)
Category: core
Target version: 
ruby -v: r40734
Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN


I'd expect a proc to either do an implicit splat or not, but right now it looks for options before doing the implicit splat. Should it not do it after doing the implicit splat?

I thought that when a proc had an argument list with more than one element, it was the same to call it with a single array argument than with the same array splatted:

   Proc{|a, ...| ... }.call([...]) == Proc{|a, ...}| ... }.call(*[...]) # => Because of implicit splat

But we have currently:

  Proc.new{|a, *b, **c| p a, b, c}.call(1,2, bar: 3)
  # => 1, [2], {:bar=>3} : OK

  Proc.new{|a, *b, **c| p a, b, c}.call([1,2, bar: 3])
  # => 1, [2, {:bar=>3}], {}: Expected same as above

  Proc.new{|(a, *b), **c| p a, b, c}.call([1,2], bar: 3)
  # => 1, [2], {:bar=>3} : OK

  Proc.new{|(a, *b), **c| p a, b, c}.call([[1,2], bar: 3])
  # => [1, 2], [{:bar=>3}], {}: Expected same as above

As an additional note, this affects some methods of Enumerable when yielding multiple arguments.

For example:

    def each; yield 1, 2, bar: 3; end
    include Enumerable

    each{|a, *b, **c| p a, b, c} # => 1, [2], {:bar => 3}: ok
    detect{|a, *b, **c| p a, b, c} # => 1, [2, {:bar => 3}], {}: should be the same, no?




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