Cut 1.19.0

Author: koic

CHANGELOG.md

@@ -11,6 +11,8 @@
 
 ## master (unreleased)
 
+## 1.19.0 (2023-08-13)
+
 ### New features
 
 * [#364](https://github.com/rubocop/rubocop-performance/pull/364): Add new `Performance/MapMethodChain` cop. ([@koic][])

config/default.yml

@@ -197,7 +197,7 @@ Performance/MapMethodChain:
   Description: 'Checks if the `map` method is used in a chain.'
   Enabled: pending
   Safe: false
-  VersionAdded: '<<next>>'
+  VersionAdded: '1.19'
 
 Performance/MethodObjectAsBlock:
   Description: 'Use block explicitly instead of block-passing a method object.'

docs/antora.yml

@@ -2,6 +2,6 @@ name: rubocop-performance
 title: RuboCop Performance
 # We always provide version without patch here (e.g. 1.1),
 # as patch versions should not appear in the docs.
-version: ~
+version: '1.19'
 nav:
   - modules/ROOT/nav.adoc

docs/modules/ROOT/pages/cops.adoc

@@ -36,6 +36,7 @@ Performance cops optimization analysis for your projects.
 * xref:cops_performance.adoc#performanceinefficienthashsearch[Performance/InefficientHashSearch]
 * xref:cops_performance.adoc#performanceioreadlines[Performance/IoReadlines]
 * xref:cops_performance.adoc#performancemapcompact[Performance/MapCompact]
+* xref:cops_performance.adoc#performancemapmethodchain[Performance/MapMethodChain]
 * xref:cops_performance.adoc#performancemethodobjectasblock[Performance/MethodObjectAsBlock]
 * xref:cops_performance.adoc#performanceopenstruct[Performance/OpenStruct]
 * xref:cops_performance.adoc#performancerangeinclude[Performance/RangeInclude]

docs/modules/ROOT/pages/cops_performance.adoc

@@ -1175,6 +1175,59 @@ ary.map(&:foo).compact!
 ary.compact.map(&:foo)
 ----
 
+== Performance/MapMethodChain
+
+|===
+| Enabled by default | Safe | Supports autocorrection | Version Added | Version Changed
+
+| Pending
+| No
+| No
+| 1.19
+| -
+|===
+
+Checks if the map method is used in a chain.
+
+Autocorrection is not supported because an appropriate block variable name cannot be determined automatically.
+
+[source,ruby]
+----
+class X
+  def initialize
+    @@num = 0
+  end
+
+  def foo
+    @@num += 1
+    self
+  end
+
+  def bar
+    @@num * 2
+  end
+end
+
+[X.new, X.new].map(&:foo).map(&:bar) # => [4, 4]
+[X.new, X.new].map { |x| x.foo.bar } # => [2, 4]
+----
+
+=== Safety
+
+This cop is unsafe because false positives occur if the number of times the first method is executed
+affects the return value of subsequent methods.
+
+=== Examples
+
+[source,ruby]
+----
+# bad
+array.map(&:foo).map(&:bar)
+
+# good
+array.map { |item| item.foo.bar }
+----
+
 == Performance/MethodObjectAsBlock
 
 |===

lib/rubocop/performance/version.rb

@@ -4,7 +4,7 @@ module RuboCop
   module Performance
     # This module holds the RuboCop Performance version information.
     module Version
-      STRING = '1.18.0'
+      STRING = '1.19.0'
 
       def self.document_version
         STRING.match('\d+\.\d+').to_s

relnotes/v1.19.0.md

@@ -0,0 +1,6 @@
+### New features
+
+* [#364](https://github.com/rubocop/rubocop-performance/pull/364): Add new `Performance/MapMethodChain` cop. ([@koic][])
+* [#363](https://github.com/rubocop/rubocop-performance/pull/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][])
+
+[@koic]: https://github.com/koic