Backport #7935: Array#sample with random generator

• Status: Closed
• Priority: Normal
• Assignee: Tomoyuki Chikanaga

[Marc-Andre Lafortune]

The Random generator method's rand is called with the wrong limit.

Kernel::rand(n) returns integer between 0 and n-1, but generator is called with (n-1).

For example:

require 'delegate'
[1, 2].sample(1, random: Random.new) # => [1], or [2]
[1, 2].sample(1, random: SimpleDelegator.new(Random.new)) # => [1], never [2]

test_random_ulong_limited

[Nobuyoshi Nakada]

• Status changed from Open to Closed
• % Done changed from 0 to 100

This issue was solved with changeset r39466.
Marc-Andre, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

---

random.c: increase limit for generic rand

• random.c (rb_random_ulong_limited): limit is inclusive, but generic rand method should return a number less than it, so increase for the difference. [Bug #7935]

[Nobuyoshi Nakada]

• Tracker changed from Bug to Backport
• Project changed from Ruby trunk to Backport200
• Category deleted (core)
• Status changed from Closed to Assigned
• Assignee set to Yusuke Endoh
• Target version deleted (next minor)

[Tomoyuki Chikanaga]

• Assignee changed from Yusuke Endoh to Tomoyuki Chikanaga

[Tomoyuki Chikanaga]

• Status changed from Assigned to Closed

This issue was solved with changeset r39675.
Marc-Andre, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

---

merge revision(s) 39466,39470: [Backport #7935]

* random.c (rb_random_ulong_limited): limit is inclusive, but generic
  rand method should return a number less than it, so increase for the
  difference.   [Bug #7935]

* test/ruby/test_array.rb (test_sample_random): remove adjustment for
  the bug fixed by r39466.   [Bug #7935]