From: Marc-Andre Lafortune <redmine@...>
Date: 2009-06-25T03:25:16+09:00
Subject: [ruby-core:24017] [Bug #1686] Enumerable#first broken

Bug #1686: Enumerable#first broken
http://redmine.ruby-lang.org/issues/show/1686

Author: Marc-Andre Lafortune
Status: Open, Priority: High
Category: core, Target version: 1.9.2
ruby -v: ruby 1.9.2dev (2009-06-24 trunk 23840) [i386-darwin9.7.0]

Enumerable#first is broken in the current HEAD. If 4 <= n < enum_length + 4, enum.first(n) returns the (n-4)th element instead of an array of n elements. E.g.:

to6 = (1..6).to_enum  # necessary so Enumerable#first is used
p to6.first(2)  # ==> [1, 2]
p to6.first(4)  # ==> 1
p to6.first(9)  # ==> 6
p to6.first(10) # ==> [1, 2, 3, 4, 5, 6]

This is due to http://redmine.ruby-lang.org/repositories/diff/ruby-19/enum.c?rev=23622 , after which ary[0] holds "n" as a long instead of a Fixnum. The comparison to Qnil isn't working as desired.

Either ary[0] holds INT2NUM(len) and first_i calls NUM2LONG + INT2NUM (as per my original patch, see http://redmine.ruby-lang.org/issues/show/1554 ) or alternatively, enum_first could use take_i or enum_take when there is an argument, since they behave the same way in that case.


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