Ruby

It's not what I expected, but Ruby is splitting test2 into two hashes, with all keywords into the second hash. There are no keywords in {0 => [0, 1]}, so Ruby passes {0 => [0, 1]} as foo and {} as keywords.

def argtest2 foo = nil, bar: nil printf "foo = %p (%p), bar: %p\n", foo, foo.class, bar end argtest2(0 => [0, 1], bar: 2) # => foo = {0=>[0, 1]} (Hash), bar: 2 argtest2(bar: 2, 0 => [0, 1]) # => foo = {0=>[0, 1]} (Hash), bar: 2 argtest2(0 => [0, 1]) # => foo = {0=>[0, 1]} (Hash), bar: nil 

So argtest2(test2) acts like argtest2(0 => [0, 1]). I don't know why Ruby does this split, or why Ruby 2.1 was different.

I get the same odd behavior with:

ruby --version ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-linux]

./ruby --version ruby 2.4.0preview2 (2016-09-09 trunk 56129) [x86_64-linux]

It looks like the combination ( foo = nil, bar: nil ) causes the issue.

On 10/31/2016 01:01 AM, nobu@ruby-lang.org wrote:

Issue #12821 has been updated by Nobuyoshi Nakada.

Subject changed from Object converted to Hash unexpectedly uder certain method call to Object converted to Hash unexpectedly under certain method call
Description updated

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Bug #12821: Object converted to Hash unexpectedly under certain method call
https://bugs.ruby-lang.org/issues/12821#change-61140

• Author: Hiroyuki Tanaka
• Status: Open
• Priority: Normal
• Assignee:
• ruby -v: 2.2.5p319, 2.3.1p112, 2.4.0-preview2
• Backport: 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN

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Hi,

I saw a bit strange behavior (at least for me) with the code below; an object given as an argument to a method with a default value and a keyword argument becomes Hash class if the object has 'to_hash' method with ruby >= 2.2, but it is not converted to Hash with ruby 2.1.
I expected the behavior of ruby 2.1.
Is this a bug or expected behavior of ruby >= 2.2?

I tested both on Linux x86_64 (CentOS 6) and Mac OS X 10.11.6.

class Test1 end class Test2 def to_hash {0 => [0, 1]} end end def argtest1 foo, bar: nil p foo.class end def argtest2 foo = nil, bar: nil p foo.class end test1 = Test1.new test2 = Test2.new argtest1(test1) # => Test1 argtest1(test2) # => Test2 argtest2(test1) # => Test1 argtest2(test2) # => Hash (2.2.5p319, 2.3.1p112, 2.4.0-preview2), Test2 (2.1.10p492) 

Regards,
Hiroyuki Tanaka