Change log

master (unreleased)

1.27.0 (2026-08-16)

Bug fixes

*#532: Fix false negatives for Performance/ChainArrayAllocation when using flat_map, filter_map, and collect_concat. (@koic)

Changes

*#530: Speed up loading rubocop-performance by lazily loading only the cops needed for a run. This requires RuboCop 1.89.0+. (@koic)

1.26.1 (2025-10-18)

Bug fixes

*#517: Fix false positives for Performance/RedundantStringChars when using str.chars[0, 2]. (@koic)

Changes

*#520: Disable Performance/BigDecimalWithNumericArgument by default. (@earlopain)

1.26.0 (2025-09-06)

Bug fixes

*#444: Fix an incorrect autocorrect for Performance/BlockGivenWithExplicitBlock when using Naming/BlockForwarding's autocorrection together. (@a-lavis) *#500: Mark Performance/MapCompact cop as unsafe. (@jbpextra) *#498: Fix Performance/Count cop error on empty selector block. (@viralpraxis) *#504: Fix autocorrection syntax error for Performance/Count with multiline calls. (@lovro-bikic)

Changes

*#512: Detect negated conditions like !foo.start_with('bar') && !foo.start_with('baz') with Performance/DoubleStartEndWith. (@earlopain)

1.25.0 (2025-04-01)

New features

*#496: Support it block parameter in Performance cops. (@koic)

Bug fixes

*#494: Fix Performance/FixedSize false positive when count is called with a numblock. (@dvandersluis) *#492: Fix false positives for Performance/StringIdentifierArgument when using interpolated string argument. (@koic)

Changes

*#482: Change Performance/CollectionLiteralInLoop to not register offenses for Array#include? that are optimized directly in Ruby. (@earlopain)

1.24.0 (2025-02-16)

New features

*#490: Pluginfy RuboCop Performance. (@koic) *#462: Add new Performance/ZipWithoutBlock cop that checks patterns like .map { |id| [id] } or .map { [_1] } and can replace them with .zip. (@corsonknowles)

Bug fixes

*#484: Fix Performance/CaseWhenSplat cop error on when node without body. (@viralpraxis)

1.23.1 (2025-01-04)

Bug fixes

*#478: Fix Performance/RedundantStringChars cop error in case of implicit receiver. (@viralpraxis) *#480: Fix Performance/Squeeze cop error on frozen AST string node value. (@viralpraxis)

1.23.0 (2024-11-14)

New features

*#474: Add new Performance/StringBytesize cop. (@viralpraxis)

1.22.1 (2024-09-17)

Bug fixes

*#468: Fix false positives for Performance/BigDecimalWithNumericArgument when using float argument for BigDecimal. (@koic)

1.22.0 (2024-09-16)

Bug fixes

*#454: Fix false positives for Performance/BigDecimalWithNumericArgument when using BigDecimal 3.1+. (@koic)

Changes

*#385: Disable Performance/BlockGivenWithExplicitBlock by default. (@earlopain) *#407: Make Performance/DoubleStartEndWith aware of safe navigation. (@earlopain)

1.21.1 (2024-06-16)

Bug fixes

*#452: Fix an error for Performance/RedundantEqualityComparisonBlock when the block is empty. (@earlopain)

1.21.0 (2024-03-30)

New features

*#446: Support Prism as a Ruby parser (experimental). (@koic)

Bug fixes

*#437: Fix a false positive for Performance/ChainArrayAllocation when using select with block argument after select. (@koic) *#448: Fix a false positive for Performance/RedundantBlockCall when using block.call with block argument. (@koic)

Changes

*#240: Disable Performance/Casecmp cop by default. (@parkerfinch)

1.20.2 (2024-01-08)

Bug fixes

*#425: Fix a false positive for Performance/StringIdentifierArgument when using string interpolation with methods that don't support symbols with :: inside them. (@earlopain)

1.20.1 (2023-12-25)

Bug fixes

*#428: Fix false negatives for Performance/StringIdentifierArgument when using multiple string arguments. (@koic)

1.20.0 (2023-12-16)

New features

*#384: Support optimized String#dup for Performance/UnfreezeString when Ruby 3.3+. (@koic)

Bug fixes

*#374: Fix an error for Performance/MapMethodChain when using map method chain without receiver. (@koic) *#386: Fix a false negative for Performance/StringIdentifierArgument when using string interpolation. (@earlopain) *#419: Make Performance/Count, Performance/FixedSize, Performance/FlatMap, Performance/InefficientHashSearch, Performance/RangeInclude, Performance/RedundantSortBlock, Performance/ReverseFirst, Performance/SelectMap, Performance/Size, Performance/SortReverse, and Performance/TimesMap cops aware of safe navigation operator. (@koic) *#390: Fix a false negative for Performance/ReverseEach when safe navigation is between reverse and each. (@fatkodima) *#401: Make Performance/Sum aware of safe navigation operator. (@koic)

Changes

*#389: Improve Performance/MapCompact to handle more safe navigation calls. (@fatkodima) *#395: Enhance Performance/StringInclude to handle === method. (@fatkodima) *#388: Require RuboCop 1.30+ as runtime dependency. (@koic) *#380: Require RuboCop AST 1.30.0+. (@koic)

1.19.1 (2023-09-17)

Bug fixes

*#367: Fix an incorrect autocorrect for Performance/BlockGivenWithExplicitBlock when using Lint/UnusedMethodArgument's autocorrection together. (@ymap) *#370: Fix an incorrect autocorrect for Performance/RedundantMatch when expressions with lower precedence than =~ are used as an argument. (@ymap) *#365: Fix false positives for Performance/ArraySemiInfiniteRangeSlice when using [] with string literals. (@koic) *#373: Set target version for Performance/UnfreezeString. (@tagliala)

1.19.0 (2023-08-13)

New features

*#364: Add new Performance/MapMethodChain cop. (@koic) *#363: Support safe navigation operator for Performance/ArraySemiInfiniteRangeSlice, Performance/DeletePrefix, Performance/DeleteSuffix, Performance/Detect, Performance/EndWith, Performance/InefficientHashSearch, Performance/MapCompact, Performance/RedundantSplitRegexpArgument, Performance/ReverseEach, Performance/ReverseFirst, Performance/SelectMap, Performance/Squeeze, Performance/StartWith, Performance/StringInclude, and Performance/StringReplacement cops. (@koic)

1.18.0 (2023-05-21)

Bug fixes

*#359: Fix a false positive for Performance/RedundantEqualityComparisonBlock when the block variable is used on both sides of ==. (@koic) *#351: Fix an incorrect autocorrect for Performance/ConstantRegexp and Performance/RegexpMatch when autocorrecting both at the same time. (@fatkodima)

Changes

*#357: Add sort! and minmax to Performance/CompareWithBlock. (@vlad-pisanov) *#353: (Breaking) Drop Ruby 2.6 support. (@koic)

1.17.1 (2023-04-09)

Bug fixes

*#352: Fix the default config for AllowRegexpMatch option of Performance/RedundantEqualityComparisonBlock. (@koic)

1.17.0 (2023-04-09)

New features

*#347: Add AllowRegexpMatch option to Performance/RedundantEqualityComparisonBlock. (@koic)

Bug fixes

*#346: Fix a false positive for Performance/StringIdentifierArgument when using a command method with receiver. (@koic) *#344: Fix Performance/FlatMap autocorrection for chained methods on separate lines. (@fatkodima)

1.16.0 (2023-02-06)

Changes

*#332: Register offenses for variables against regexes in Performance/StringInclude. (@fatkodima)

1.15.2 (2022-12-25)

Bug fixes

*#313: Fix a false negative for Performance/RedundantStringChars when using str.chars.last without argument. (@koic) *#321: Fix a false positive for Performance/Sum when using TargetRubyVersion is 2.3 or lower. (@koic) *#314: Fix Performance/RegexpMatch to handle ::Regexp. (@fatkodima)

Changes

*#318: Extend Performance/StringInclude to handle !~. (@fatkodima)

1.15.1 (2022-11-16)

Bug fixes

*#309: Fix an error for Performance/MapCompact when using map(&:do_something).compact and there is a line break after map.compact and assigning with ||=. (@koic)

Changes

*#307: Support autocorrection even if reject is used on Performance/Count. (@r7kamura)

1.15.0 (2022-09-10)

New features

*#305: Support numbered parameter for Performance/RedundantSortBlock, Performance/SortReverse, and Performance/TimesMap cops. (@koic)

Bug fixes

*#299: Fix incorrect documentation URLs when using rubocop --show-docs-url. (@r7kamura)

Changes

*#297: Support autocorrection on Performance/RedundantMatch when receiver is a Regexp literal. (@r7kamura)

1.14.3 (2022-07-17)

Bug fixes

*#296: Fix a false negative for Performance/StringIdentifierArgument when using instance_variable_defined?. (@koic) *#294: Fix a false negative for Performance/ChainArrayAllocation when using array.first(do_something).uniq. (@koic)

1.14.2 (2022-06-08)

Bug fixes

*#292: Fix a false positive for Performance/RegexpMatch when TargetRubyVersion: 2.3. (@koic)

1.14.1 (2022-06-05)

Bug fixes

*#291: Fix Performance/MapCompact autocorrect causing invalid syntax when using multiline map { ... }.compact as an argument for an assignment method. (@QQism)

1.14.0 (2022-05-24)

Bug fixes

*#289: Fix a false positive for Performance/StringIdentifierArgument when using namespaced class string argument. (@koic) *#288: Recover Ruby 2.4 code analysis using TargetRubyVersion: 2.4. (@koic)

Changes

*#287: (Compatibility) Drop Ruby 2.5 support. (@koic)

1.13.3 (2022-03-05)

Bug fixes

*#285: Fix an error for Performance/MapCompact when using map(&:do_something).compact.first and there is a line break after map.compact and receiver. (@ydah)

1.13.2 (2022-01-16)

Bug fixes

*#281: Fix an error for Performance/BlockGivenWithExplicitBlock when using Ruby 3.1's anonymous block forwarding. (@koic)

1.13.1 (2022-01-01)

Bug fixes

*#278: Fix a false positive for Performance/StringIdentifierArgument when using attr. (@koic)

1.13.0 (2021-12-25)

New features

*#276: Add new Performance/StringIdentifierArgument cop. (@koic) *#204: Add Performance/Sum option to ignore potential false positives. (@leoarnold) *#269: Add #to_d support to BigDecimalWithNumericArgument. (@leoarnold)

Bug fixes

*#277: Fix an incorrect autocorrect for Performance/MapCompact when using map.compact.first and there is a line break after map.compact and receiver. (@koic) *#273: Fix an incorrect autocorrect for Performance/RedundantStringChars when using str.chars. (@koic)

Changes

*#270: Mark Performance/Sum auto-correction as unsafe and extend documentation. (@leoarnold) *#274: Unmark AutoCorrect: false from Performance/CaseWhenSplat. (@koic) *#275: Unmark AutoCorrect: false from Performance/TimesMap. (@koic)

1.12.0 (2021-10-31)

New features

*#267: Add new Performance/ConcurrentMonotonicTime cop. (@koic)

Bug fixes

*#261: Fix a false negative for Performance/RedundantBlockCall when using block.call in a class method'. (@koic) *#264: Fix error in Performance/Sum when method has no brackets. (@mvz)

Changes

*#263: Unmark AutoCorrect: false from Performance/StringInclude. (@koic)

1.11.5 (2021-08-18)

Bug fixes

*#255: Fix a false positive for Performance/RedundantEqualityComparisonBlock when using block argument is used for an argument of operand. (@koic) *#257: Fix an incorrect auto-correct for Performance/MapCompact when using multi-line collection.map { ... }.compact as a method argument. (@koic)

1.11.4 (2021-07-07)

Bug fixes

*#247: Fix an incorrect auto-correct for Performance/MapCompact when using multi-line trailing dot method calls. (@koic) *#249: Fix a false positive for Performance/RedundantStringChars when using str.chars.last and str.chars.drop. (@koic) *#252: Fix an incorrect auto-correct for Performance/UnfreezeString when invoking a method after String.new with a string. (@koic)

Changes

*#245: Mark Performance/DeletePrefix and Performance/DeleteSuffix as unsafe. (@koic)

1.11.3 (2021-05-06)

Bug fixes

*#242: Fix an error for Performance/MapCompact when using multiline map { ... }.compact and assigning to return value. (@koic)

1.11.2 (2021-05-05)

Bug fixes

*#238: Fix an incorrect auto-correct for Performance/MapCompact when invoking a method after map { ... }.compact on the same line. (@koic)

1.11.1 (2021-05-02)

Bug fixes

*#236: Fix an incorrect auto-correct for Performance/MapCompact when using multi-line leading dot method calls. (@koic)

1.11.0 (2021-04-22)

New features

*#229: Add new Performance/MapCompact cop. (@koic) *#178: Add new Performance/SelectMap cop. (@koic)

Bug fixes

*#230: Fix a false positive for Performance/ChainArrayAllocation when using Enumerable#lazy. (@koic)

Changes

*#228: Mark Performance/RedundantMerge as unsafe. (@dvandersluis) *#232: (Compatibility) Drop Ruby 2.4 support. (@koic) *#235: Require RuboCop 1.7 or higher. (@koic)

1.10.2 (2021-03-23)

Bug fixes

*#162: Fix a false positive for Performance/RedundantBlockCall when an optional block that is overridden by block variable. (@koic) *#36: Fix a false positive for Performance/ReverseEach when each is called on reverse and using the result value. (@koic) *#224: Fix a false positive for Style/RedundantEqualityComparisonBlock when using one argument with comma separator in block argument. (@koic) *#225: Fix a false positive for Style/RedundantEqualityComparisonBlock when using any? with === comparison block and block argument is not used as a receiver for ===. (@koic) *#222: Fix a false positive for Performance/RedundantSplitRegexpArgument when split method argument is exactly one space regexp / /. (@koic)

1.10.1 (2021-03-02)

Bug fixes

*#214: Fix a false positive for Performance/RedundantEqualityComparisonBlock when using multiple block arguments. (@koic) *#216: Fix a false positive for Performance/RedundantSplitRegexpArgument when using split method with ignore case regexp option. (@koic) *#217: Fix a false positive for Performance/RedundantEqualityComparisonBlock when using block argument is used for an argument of is_a. (@koic)

1.10.0 (2021-03-01)

New features

*#190: Add new Performance/RedundantSplitRegexpArgument cop. (@mfbmina) *#213: Add new Performance/RedundantEqualityComparisonBlock cop. (@koic)

Bug fixes

*#207: Fix an error for Performance/Sum when using map(&do_something).sum without receiver. (@koic) *#210: Fix a false negative for Performance/BindCall when receiver is not a method call. (@koic)

Changes

*#205: Update Performance/ConstantRegexp to allow memoized regexps. (@dvandersluis) *#212: Enable unsafe auto-correct for Performance/StartWith and Performance/EndWith cops by default. (@koic)

1.9.2 (2021-01-01)

Bug fixes

*#201: Fix an incorrect auto-correct for Performance/ReverseEach when using multi-line reverse.each with leading dot. (@koic)

1.9.1 (2020-11-28)

Bug fixes

*#185: Fix incorrect replacement recommendation for Performance/ChainArrayAllocation. (@fatkodima)

Changes

*#197: Disable Performance/ArraySemiInfiniteRangeSlice cop. (@tejasbubane)

1.9.0 (2020-11-17)

New features

*#173: Add new Performance/BlockGivenWithExplicitBlock cop. (@fatkodima) *#136: Add new Performance/MethodObjectAsBlock cop. (@fatkodima) *#151: Add new Performance/ConstantRegexp cop. (@fatkodima) *#175: Add new Performance/ArraySemiInfiniteRangeSlice cop. (@fatkodima) *#189: Support auto-correction for Performance/Caller. (@koic) *#171: Extend auto-correction support for Performance/Sum. (@koic) *#194: Support auto-correction for Performance/UnfreezeString. (@koic)

Changes

*#181: Change default configuration for Performance/CollectionLiteralInLoop to Enabled: 'pending'. (@ghiculescu) *#170: Extend Performance/Sum to register an offense for map { ... }.sum. (@eugeneius) *#179: Change Performance/Sum to warn about empty arrays, and not register an offense on empty array literals. (@ghiculescu) *#180: Require RuboCop 0.90 or higher. (@koic)

1.8.1 (2020-09-19)

Bug fixes

*#164: Fix an error for Performance/CollectionLiteralInLoop when a method from Enumerable is called with no receiver. (@eugeneius) *#165: Fix a false positive for Performance/Sum when using initial value argument is a variable. (@koic)

Changes

*#163: Change Performance/Detect to also detect offenses when index 0 or -1 is used instead (ie. detect<a href='0'> ... </a>). (@dvandersluis) *#168: Extend Performance/Sum to register an offense for inject(&:+). (@eugeneius)

1.8.0 (2020-09-04)

New features

*#140: Add new Performance/CollectionLiteralInLoop cop. (@fatkodima) *#137: Add new Performance/Sum cop. (@fatkodima)

Bug fixes

*#159: Fix a false positive for Performance/AncestorsInclude when receiver is a variable. (@koic)

Changes

*#157: Extend Performance/Detect cop with check for filter method and Performance/Count cop with checks for find_all and filter methods. (@fatkodima) *#154: Require RuboCop 0.87 or higher. (@koic)

1.7.1 (2020-07-18)

Bug fixes

*#147: Fix an error for Performance/AncestorsInclude when using ancestors.include? without receiver. (@koic) *#150: Fix an incorrect autocorrect for Performance/BigDecimalWithNumericArgument when a precision is specified. (@eugeneius)

Changes

*#149: Mark Performance/AncestorsInclude as unsafe. (@eugeneius) *#145: Mark Performance/StringInclude as SafeAutocorrect: false and disable autocorrect by default. (@koic)

1.7.0 (2020-07-07)

New features

*#141: Add new Performance/RedundantStringChars cop. (@fatkodima) *#127: Add new Performance/IoReadlines cop. (@fatkodima) *#128: Add new Performance/ReverseFirst cop. (@fatkodima) *#132: Add new Performance/RedundantSortBlock cop. (@fatkodima) *#125: Support Array() and Hash() methods for Performance/Size cop. (@fatkodima) *#124: Add new Performance/Squeeze cop. (@fatkodima) *#129: Add new Performance/BigDecimalWithNumericArgument cop. (@fatkodima) *#130: Add new Performance/SortReverse cop. (@fatkodima) *#81: Add new Performance/StringInclude cop. (@fatkodima) *#123: Add new Performance/AncestorsInclude cop. (@fatkodima) *#125: Support Range#member? method for Performance/RangeInclude cop. (@fatkodima)

Changes

*#138: Drop support for RuboCop 0.81 or lower. (@koic)

1.6.1 (2020-06-05)

New features

*#115: Support String#sub and String#sub! methods for Performance/DeletePrefix and Performance/DeleteSuffix cops. (@fatkodima)

Bug fixes

*#111: Fix an error for Performance/DeletePrefix and Performance/DeleteSuffix cops when using autocorrection with RuboCop 0.81 or lower. (@koic) *#118: Fix a false positive for Performance/DeletePrefix, Performance/DeleteSuffix, Performance/StartWith, and Performance/EndWith cops when receiver is multiline string. (@koic)

1.6.0 (2020-05-22)

New features

*#77: Add new Performance/BindCall cop. (@koic) *#105: Add new Performance/DeletePrefix and Performance/DeleteSuffix cops. (@koic) *#107: Support regexp metacharacter ^ for Performance/StartWith cop and regexp metacharacter $ for Performance/EndWith cop. (@koic)

Bug fixes

*#55: Fix an incorrect autocorrect for Performance/RegexpMatch when using str.=~(/regexp/). (@koic) *#108: Fix an incorrect autocorrect for Performance/ReverseEach when there is a newline between reverse and each. (@joe-sharp, @dischorde, @siegfault)

Changes

*#103: (Compatibility) Drop support for Ruby 2.3. (@koic) *#101: Mark unsafe for Performance/Casecmp cop. (@koic)

1.5.2 (2019-12-25)

Bug fixes

*#86: Fix an incorrect autocorrect for Performance/RedundantMerge when using an empty hash argument. (@koic)

1.5.1 (2019-11-14)

Bug fixes

*#82: Let Performance/StartWith and Performance/EndWith correct Regexp#match? and Regexp#=~. (@eugeneius)

1.5.0 (2019-10-01)

Bug fixes

*#74: Fix an error for Performance/RedundantMerge when MaxKeyValuePairs option is set to null. (@koic) *#70: This PR fixes a false negative for Performance/FlatMap when using symbol to proc operator argument of map method. (@koic, @splattael)

Changes

*#69: Remove SafeMode from Performance/Count and Performance/Detect. Set SafeAutoCorrect to false for these cops by default. (@rrosenblum)

1.4.1 (2019-07-29)

Bug fixes

*#67: Fix an error for Performance/RedundantMerge when MaxKeyValuePairs option is set to null. (@koic) *#73: Fix a false negative for Performance/RegexpMatch when MatchData is not detected in if branch of guard condition. (@koic)

1.4.0 (2019-06-20)

Bug fixes

*#54: Fix Performance/FixedSize to accept const assign with some operation. (@tejasbubane) *#61: Fix a false negative for Performance/RegexpMatch when using RuboCop 0.71 or higher. (@koic)

1.3.0 (2019-05-13)

Bug fixes

*#48: Reduce Performance/RegexpMatch false positive by only flagging match used with Regexp/String/Symbol literals. (@dduugg)

Changes

*#52: (Compatibility) Drop support for Ruby 2.2. (@bquorning)

1.2.0 (2019-05-04)

Bug fixes

*#47: Fix a false negative for Performance/RegexpMatch when using RuboCop 0.68 or higher. (@koic)

1.1.0 (2019-04-08)

Changes

*#39: Remove Performance/LstripRstrip cop. (@koic) *#39: Remove Performance/RedundantSortBy, Performance/UnneededSort and Performance/Sample cops. (@koic)

1.0.0 (2019-03-14)

New features

• Extract performance cops from rubocop/rubocop repository. (@composerinteralia, @koic)