Bug #14259: Integer#pow returns an invalid result with large modulo

• Status: Closed
• Assignee: mrkn (Kenta Murata)
• Target version: -
• ruby -v: ruby 2.5.0p0 (2017-12-25 revision 61468) [x86_64-darwin16]
• Backport: 2.3: DONTNEED, 2.4: DONTNEED, 2.5: DONE

[mrkn (Kenta Murata)]

irb(main):020:0> 12.pow(1, 10000000000)
=> 1
irb(main):021:0> 12.pow(1, 10000000001)
=> 1
irb(main):022:0> 12.pow(1, 10000000002)
=> 1

These results should be 12.

[mrkn (Kenta Murata)]

• ruby -v set to ruby 2.5.0p0 (2017-12-25 revision 61468) [x86_64-darwin16]

[mrkn (Kenta Murata)]

• Status changed from Assigned to Closed

Applied in changeset trunk|r61517.

---

numeric.c: Fix Integer#pow with a large Fixnum modulo

• numeric.c: Fix Integer#pow with a large Fixnum modulo
  [Bug #14259] [ruby-core:84562]

• test/ruby/test_numeric.rb: add assertions for reproducing this bug.

[mrkn (Kenta Murata)]

• Backport changed from 2.3: UNKNOWN, 2.4: UNKNOWN, 2.5: UNKNOWN to 2.3: UNKNOWN, 2.4: UNKNOWN, 2.5: REQUIRED

[andrykonchin (Andrew Konchin)]

Another example:

2.pow(61, 9213693951) # => 1

Expected following result:

(2 ** 61) % 9213693951 # => 5432161352

[naruse (Yui NARUSE)]

• Backport changed from 2.3: UNKNOWN, 2.4: UNKNOWN, 2.5: REQUIRED to 2.3: UNKNOWN, 2.4: UNKNOWN, 2.5: DONE

ruby_2_5 r61629 merged revision(s) 61517.

[usa (Usaku NAKAMURA)]

• Backport changed from 2.3: UNKNOWN, 2.4: UNKNOWN, 2.5: DONE to 2.3: DONTNEED, 2.4: DONTNEED, 2.5: DONE

[sawa (Tsuyoshi Sawada)]

• Subject changed from Integer#pow returns a Invalid result with a large modulo to Integer#pow returns an invalid result with large modulo
• Description updated (diff)