From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-Status: No, score=-4.1 required=3.0 tests=AWL,BAYES_00, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from neon.ruby-lang.org (neon.ruby-lang.org [221.186.184.75]) by dcvr.yhbt.net (Postfix) with ESMTP id BC8DB1F4B4 for ; Sat, 10 Oct 2020 06:55:04 +0000 (UTC) Received: from neon.ruby-lang.org (localhost [IPv6:::1]) by neon.ruby-lang.org (Postfix) with ESMTP id 1025B120975; Sat, 10 Oct 2020 15:54:26 +0900 (JST) Received: from xtrwkhkc.outbound-mail.sendgrid.net (xtrwkhkc.outbound-mail.sendgrid.net [167.89.16.28]) by neon.ruby-lang.org (Postfix) with ESMTPS id CA974120974 for ; Sat, 10 Oct 2020 15:54:24 +0900 (JST) Received: by filterdrecv-p3iad2-6fcd869f88-nxx85 with SMTP id filterdrecv-p3iad2-6fcd869f88-nxx85-18-5F815AC2-25 2020-10-10 06:54:58.852433202 +0000 UTC m=+202818.641861434 Received: from herokuapp.com (unknown) by geopod-ismtpd-1-4 (SG) with ESMTP id tm3JS6lVTnSU6yO2M-JecQ for ; Sat, 10 Oct 2020 06:54:58.801 +0000 (UTC) Date: Sat, 10 Oct 2020 06:54:58 +0000 (UTC) From: nobu@ruby-lang.org Message-ID: References: Mime-Version: 1.0 X-Redmine-MailingListIntegration-Message-Ids: 76221 X-Redmine-Project: ruby-master X-Redmine-Issue-Tracker: Bug X-Redmine-Issue-Id: 17257 X-Redmine-Issue-Author: universato X-Redmine-Issue-Assignee: mrkn X-Redmine-Sender: nobu X-Mailer: Redmine X-Redmine-Host: bugs.ruby-lang.org X-Redmine-Site: Ruby Issue Tracking System X-Auto-Response-Suppress: All Auto-Submitted: auto-generated X-SG-EID: =?us-ascii?Q?q8Dly+pU2+3ektTtZVXgZtbJPXwqo7p86jCsvYTW4ByYxZ23TUioWjqwaHdmxK?= =?us-ascii?Q?fWk=2F4rmSRK254OhC24rt7h147XMNsEtitIYfnnH?= =?us-ascii?Q?zzdApu9cQ2TXU=2FfIhOTD2yC81ASlsp75PsF8zg9?= =?us-ascii?Q?BecsaJ3dt+ar6ZQcY=2F64Tk6IV9QqKAUfR8rC1CV?= =?us-ascii?Q?CkdPBVOzxGUyOw7949Zv8m89XYQ6Q=2F56lIEtW77?= =?us-ascii?Q?8n337DJMsX938oH3o=3D?= To: ruby-core@ruby-lang.org X-Entity-ID: b/2+PoftWZ6GuOu3b0IycA== X-ML-Name: ruby-core X-Mail-Count: 100355 Subject: [ruby-core:100355] [Ruby master Bug#17257] Integer#pow(0, 1) returns 1, which is incorrect X-BeenThere: ruby-core@ruby-lang.org X-Mailman-Version: 2.1.15 Precedence: list Reply-To: Ruby developers List-Id: Ruby developers List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ruby-core-bounces@ruby-lang.org Sender: "ruby-core" Issue #17257 has been updated by nobu (Nobuyoshi Nakada). Assignee set to mrkn (Kenta Murata) Status changed from Open to Assigned I'm not sure if it should be 0. As `x.pow(y, m)` equals multiplying `x % m` to 1 `y` times, isn't 1 ok when `x == 0`? ---------------------------------------- Bug #17257: Integer#pow(0, 1) returns 1, which is incorrect https://bugs.ruby-lang.org/issues/17257#change-87967 * Author: universato (Yoshimine Sato) * Status: Assigned * Priority: Normal * Assignee: mrkn (Kenta Murata) * Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN ---------------------------------------- Ruby 2.5.8, 2.6.6, 2.7.1 ```ruby p -1.pow(0, 1) #=> 1 p 0.pow(0, 1) #=> 1 p 1.pow(0, 1) #=> 1 p 1234567890.pow(0, 1) #=> 1 ``` These return values should be 0. Patch for test: Let's add some boundary value tests to `test_pow` of [test_numeric.rb](https://github.com/ruby/ruby/blob/e014e6bf6685f681998238ff005f6d161d43ce51/test/ruby/test_numeric.rb). ```ruby integers = [-2, -1, 0, 1, 2, 3, 6, 1234567890123456789] integers.each do |i| assert_equal(0, i.pow(0, 1), '[Bug #17257]') assert_equal(1, i.pow(0, 2)) assert_equal(1, i.pow(0, 3)) assert_equal(1, i.pow(0, 6)) assert_equal(1, i.pow(0, 1234567890123456789)) assert_equal(0, i.pow(0, -1)) assert_equal(-1, i.pow(0, -2)) assert_equal(-2, i.pow(0, -3)) assert_equal(-5, i.pow(0, -6)) assert_equal(-1234567890123456788, i.pow(0, -1234567890123456789)) end assert_equal(0, 0.pow(2, 1)) assert_equal(0, 0.pow(3, 1)) assert_equal(0, 2.pow(3, 1)) assert_equal(0, -2.pow(3, 1)) -- https://bugs.ruby-lang.org/