Support Prism as a Ruby parser

Follow up rubocop/rubocop-ast#277

In Prism (`Prism::Translation::Parser`), `match-with-lvasgn` can be distinctly differentiated.

It is unclear whether to conform to the current behavior of the Parser gem, but initially,
`def_node_matcher` has been updated to accept the following incompatibilities for
`Performance/EndWith`, `Performance/StringInclude`, and `Performance/StartWith` cops
to ensure it works with Prism 0.24.0 as well.

## Parser gem

Returns an `match_with_lvasgn` node:

```console
$ bundle exec ruby -rparser/ruby33 -ve 'p Parser::Ruby33.parse("/foo/ =~ bar")'
ruby 3.3.0 (2023-12-25 revision 5124f9ac75) [x86_64-darwin22]
s(:match_with_lvasgn,
  s(:regexp,
    s(:str, "foo"),
    s(:regopt)),
  s(:send, nil, :bar))
```

Returns an `match_with_lvasgn` node:

```console
$ bundle exec ruby -rparser/ruby33 -ve 'p Parser::Ruby33.parse("/(?<foo>)foo/ =~ bar")'
ruby 3.3.0 (2023-12-25 revision 5124f9ac75) [x86_64-darwin22]
s(:match_with_lvasgn,
  s(:regexp,
    s(:str, "(?<foo>)foo"),
    s(:regopt)),
  s(:send, nil, :bar))
```

This lvar-injecting feature appears to have not been supported by Parser gem for a long time:
whitequark/parser#69 (comment)

## Prism

Returns an `send` node:

```console
$ bundle exec ruby -Ilib -rprism -rprism/translation/parser33 -ve 'p Prism::Translation::Parser33.parse("/foo/ =~ bar")'
ruby 3.3.0 (2023-12-25 revision 5124f9ac75) [x86_64-darwin22]
s(:send,
  s(:regexp,
    s(:str, "foo"),
    s(:regopt)), :=~,
  s(:send, nil, :bar))
```

Returns an `match_with_lvasgn` node:

```console
$ bundle exec ruby -Ilib -rprism -rprism/translation/parser33 -ve 'p Prism::Translation::Parser33.parse("/(?<foo>)foo/ =~ bar")'
ruby 3.3.0 (2023-12-25 revision 5124f9ac75) [x86_64-darwin22]
s(:match_with_lvasgn,
  s(:regexp,
    s(:str, "(?<foo>)foo"),
    s(:regopt)),
  s(:send, nil, :bar))
```

Author: koic

.github/workflows/test.yml

@@ -53,6 +53,22 @@ jobs:
       - name: internal_investigation
         run: bundle exec rake internal_investigation
 
+  prism:
+    runs-on: ubuntu-latest
+    name: Prism
+    steps:
+      - uses: actions/checkout@v4
+      - name: set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          # Specify the minimum Ruby version 2.7 required for Prism to run.
+          ruby-version: 2.7
+          bundler-cache: true
+      - name: spec
+        env:
+          PARSER_ENGINE: parser_prism
+        run: bundle exec rake prism_spec
+
   documentation_checks:
     runs-on: ubuntu-latest
     name: Check documentation syntax

Gemfile

@@ -7,6 +7,7 @@ git_source(:github) { |repo| "https://github.com/#{repo}.git" }
 gemspec
 
 gem 'bump', require: false
+gem 'prism'
 gem 'rake'
 gem 'rspec'
 gem 'rubocop', github: 'rubocop/rubocop'

Rakefile

@@ -27,6 +27,11 @@ task :spec do
   end
 end
 
+desc 'Run RSpec with Prism'
+task :prism_spec do
+  sh('PARSER_ENGINE=parser_prism bundle exec rake spec')
+end
+
 desc 'Run RSpec with code coverage'
 task :coverage do
   ENV['COVERAGE'] = 'true'
@@ -36,7 +41,7 @@ end
 desc 'Run RuboCop over itself'
 RuboCop::RakeTask.new(:internal_investigation)
 
-task default: %i[documentation_syntax_check spec internal_investigation]
+task default: %i[documentation_syntax_check spec prism_spec internal_investigation]
 
 desc 'Generate a new cop template'
 task :new_cop, [:cop] do |_task, args|

changelog/new_support_prism.md

@@ -0,0 +1 @@
+* [#446](https://github.com/rubocop/rubocop-performance/pull/446): Support Prism as a Ruby parser (experimental). ([@koic][])

lib/rubocop/cop/performance/end_with.rb

@@ -56,7 +56,8 @@ class EndWith < Base
         def_node_matcher :redundant_regex?, <<~PATTERN
           {(call $!nil? {:match :=~ :match?} (regexp (str $#literal_at_end?) (regopt)))
            (send (regexp (str $#literal_at_end?) (regopt)) {:match :match?} $_)
-           (match-with-lvasgn (regexp (str $#literal_at_end?) (regopt)) $_)}
+           ({send match-with-lvasgn} (regexp (str $#literal_at_end?) (regopt)) $_)
+           (send (regexp (str $#literal_at_end?) (regopt)) :=~ $_)}
         PATTERN
 
         def on_send(node)

lib/rubocop/cop/performance/start_with.rb

@@ -56,7 +56,8 @@ class StartWith < Base
         def_node_matcher :redundant_regex?, <<~PATTERN
           {(call $!nil? {:match :=~ :match?} (regexp (str $#literal_at_start?) (regopt)))
            (send (regexp (str $#literal_at_start?) (regopt)) {:match :match?} $_)
-           (match-with-lvasgn (regexp (str $#literal_at_start?) (regopt)) $_)}
+           (match-with-lvasgn (regexp (str $#literal_at_start?) (regopt)) $_)
+           (send (regexp (str $#literal_at_start?) (regopt)) :=~ $_)}
         PATTERN
 
         def on_send(node)

lib/rubocop/cop/performance/string_include.rb

@@ -29,7 +29,8 @@ class StringInclude < Base
         def_node_matcher :redundant_regex?, <<~PATTERN
           {(call $!nil? {:match :=~ :!~ :match?} (regexp (str $#literal?) (regopt)))
            (send (regexp (str $#literal?) (regopt)) {:match :match? :===} $_)
-           (match-with-lvasgn (regexp (str $#literal?) (regopt)) $_)}
+           (match-with-lvasgn (regexp (str $#literal?) (regopt)) $_)
+           (send (regexp (str $#literal?) (regopt)) :=~ $_)}
         PATTERN
 
         # rubocop:disable Metrics/AbcSize

rubocop-performance.gemspec

@@ -31,5 +31,5 @@ Gem::Specification.new do |s|
   }
 
   s.add_runtime_dependency('rubocop', '>= 1.48.1', '< 2.0')
-  s.add_runtime_dependency('rubocop-ast', '>= 1.30.0', '< 2.0')
+  s.add_runtime_dependency('rubocop-ast', '>= 1.31.1', '< 2.0')
 end

spec/rubocop/cop/performance/bind_call_spec.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 RSpec.describe RuboCop::Cop::Performance::BindCall, :config do
-  context 'when TargetRubyVersion <= 2.6', :ruby26 do
+  context 'when TargetRubyVersion <= 2.6', :ruby26, unsupported_on: :prism do
     it 'does not register an offense when using `bind(obj).call(args, ...)`' do
       expect_no_offenses(<<~RUBY)
         umethod.bind(obj).call(foo, bar)

spec/rubocop/cop/performance/collection_literal_in_loop_spec.rb

@@ -144,7 +144,9 @@
       RUBY
     end
 
-    it 'registers an offense when the method is called with no receiver' do
+    # FIXME: `undefined method `[]' for nil` occurs Prism 0.24.0. It has been resolved in
+    # the development line. This will be resolved in Prism > 0.24.0 and higher releases.
+    it 'registers an offense when the method is called with no receiver', broken_on: :prism do
       expect_offense(<<~RUBY)
         all? do |e|
           [1, 2, 3].include?(e)

spec/rubocop/cop/performance/delete_prefix_spec.rb

@@ -4,7 +4,7 @@
   let(:cop_config) { { 'SafeMultiline' => safe_multiline } }
   let(:safe_multiline) { true }
 
-  context 'when TargetRubyVersion <= 2.4', :ruby24 do
+  context 'when TargetRubyVersion <= 2.4', :ruby24, unsupported_on: :prism do
     it "does not register an offense when using `gsub(/\Aprefix/, '')`" do
       expect_no_offenses(<<~RUBY)
         str.gsub(/\\Aprefix/, '')

spec/rubocop/cop/performance/delete_suffix_spec.rb

@@ -4,7 +4,7 @@
   let(:cop_config) { { 'SafeMultiline' => safe_multiline } }
   let(:safe_multiline) { true }
 
-  context 'when TargetRubyVersion <= 2.4', :ruby24 do
+  context 'when TargetRubyVersion <= 2.4', :ruby24, unsupported_on: :prism do
     it "does not register an offense when using `gsub(/suffix\z/, '')`" do
       expect_no_offenses(<<~RUBY)
         str.gsub(/suffix\\z/, '')

spec/rubocop/cop/performance/map_compact_spec.rb

@@ -361,7 +361,7 @@
     end
   end
 
-  context 'when TargetRubyVersion <= 2.6', :ruby26 do
+  context 'when TargetRubyVersion <= 2.6', :ruby26, unsupported_on: :prism do
     it 'does not register an offense when using `collection.map(&:do_something).compact`' do
       expect_no_offenses(<<~RUBY)
         collection.map(&:do_something).compact

spec/rubocop/cop/performance/redundant_equality_comparison_block_spec.rb

@@ -149,7 +149,7 @@
     end
   end
 
-  context 'when TargetRubyVersion <= 2.4', :ruby24 do
+  context 'when TargetRubyVersion <= 2.4', :ruby24, unsupported_on: :prism do
     # Ruby 2.4 does not support `items.all?(Klass)`.
     it 'does not register an offense when using `all?` with `is_a?` comparison block' do
       expect_no_offenses(<<~RUBY)

spec/rubocop/cop/performance/redundant_merge_spec.rb

@@ -36,7 +36,9 @@
     end
   end
 
-  context 'when receiver is implicit' do
+  # FIXME: `undefined method `[]' for nil` occurs Prism 0.24.0. It has been resolved in
+  # the development line. This will be resolved in Prism > 0.24.0 and higher releases.
+  context 'when receiver is implicit', broken_on: :prism do
     it "doesn't autocorrect" do
       new_source = autocorrect_source('merge!(foo: 1, bar: 2)')
       expect(new_source).to eq('merge!(foo: 1, bar: 2)')

spec/rubocop/cop/performance/regexp_match_spec.rb

@@ -396,7 +396,7 @@ def foo
     RUBY
   end
 
-  context 'when Ruby <= 2.3', :ruby23 do
+  context 'when Ruby <= 2.3', :ruby23, unsupported_on: :prism do
     it 'does not register an offense when using `String#match` in condition' do
       expect_no_offenses(<<~RUBY)
         if 'foo'.match(re)

spec/rubocop/cop/performance/select_map_spec.rb

@@ -130,7 +130,7 @@
     end
   end
 
-  context 'when TargetRubyVersion <= 2.6', :ruby26 do
+  context 'when TargetRubyVersion <= 2.6', :ruby26, unsupported_on: :prism do
     it 'does not register an offense when using `select.map`' do
       expect_no_offenses(<<~RUBY)
         ary.select(&:present?).map(&:to_i)

spec/rubocop/cop/performance/string_identifier_argument_spec.rb

@@ -27,7 +27,9 @@
         RUBY
       end
     else
-      it "registers an offense when using string argument for `#{method}` method" do
+      # FIXME: `undefined method `[]' for nil` occurs Prism 0.24.0. It has been resolved in
+      # the development line. This will be resolved in Prism > 0.24.0 and higher releases.
+      it "registers an offense when using string argument for `#{method}` method", broken_on: :prism do
         expect_offense(<<~RUBY, method: method)
           #{method}('do_something')
           _{method} ^^^^^^^^^^^^^^ Use `:do_something` instead of `'do_something'`.
@@ -38,14 +40,18 @@
         RUBY
       end
 
-      it "does not register an offense when using symbol argument for `#{method}` method" do
+      # FIXME: `undefined method `[]' for nil` occurs Prism 0.24.0. It has been resolved in
+      # the development line. This will be resolved in Prism > 0.24.0 and higher releases.
+      it "does not register an offense when using symbol argument for `#{method}` method", broken_on: :prism do
         expect_no_offenses(<<~RUBY)
           #{method}(:do_something)
         RUBY
       end
 
       if described_class::INTERPOLATION_IGNORE_METHODS.include?(method)
-        it 'does not register an offense when using string interpolation for `#{method}` method' do
+        # FIXME: `undefined method `[]' for nil` occurs Prism 0.24.0. It has been resolved in
+        # the development line. This will be resolved in Prism > 0.24.0 and higher releases.
+        it 'does not register an offense when using string interpolation for `#{method}` method', broken_on: :prism do
           # NOTE: These methods don't support `::` when passing a symbol. const_get('A::B') is valid
           # but const_get(:'A::B') isn't. Since interpolated arguments may contain any content these
           # cases are not detected as an offense to prevent false positives.
@@ -54,7 +60,9 @@
           RUBY
         end
       else
-        it 'registers an offense when using interpolated string argument' do
+        # FIXME: `undefined method `[]' for nil` occurs Prism 0.24.0. It has been resolved in
+        # the development line. This will be resolved in Prism > 0.24.0 and higher releases.
+        it 'registers an offense when using interpolated string argument', broken_on: :prism do
           expect_offense(<<~RUBY, method: method)
             #{method}("do_something_\#{var}")
             _{method} ^^^^^^^^^^^^^^^^^^^^^ Use `:"do_something_\#{var}"` instead of `"do_something_\#{var}"`.

spec/rubocop/cop/performance/sum_spec.rb

@@ -343,7 +343,7 @@
       RUBY
     end
 
-    context 'when Ruby 2.3 or lower', :ruby23 do
+    context 'when Ruby 2.3 or lower', :ruby23, unsupported_on: :prism do
       it "does not register an offense when using `array.#{method}(10, :+)`" do
         expect_no_offenses(<<~RUBY)
           array.#{method}(10, :+)

spec/rubocop/cop/performance/unfreeze_string_spec.rb

@@ -9,7 +9,7 @@
     end
   end
 
-  context 'when Ruby <= 3.2', :ruby32 do
+  context 'when Ruby <= 3.2', :ruby32, unsupported_on: :prism do
     it 'registers an offense and corrects for an empty string with `.dup`' do
       expect_offense(<<~RUBY)
         "".dup
@@ -123,7 +123,7 @@
     RUBY
   end
 
-  context 'when Ruby <= 2.2', :ruby22 do
+  context 'when Ruby <= 2.2', :ruby22, unsupported_on: :prism do
     it 'does not register an offense for an empty string with `.dup`' do
       expect_no_offenses(<<~RUBY)
         "".dup

spec/spec_helper.rb

@@ -13,6 +13,10 @@
 
   config.shared_context_metadata_behavior = :apply_to_host_groups
   config.filter_run_when_matching :focus
+  config.filter_run_excluding broken_on: :prism if ENV['PARSER_ENGINE'] == 'parser_prism'
+
+  # Prism supports Ruby 3.3+ parsing.
+  config.filter_run_excluding unsupported_on: :prism if ENV['PARSER_ENGINE'] == 'parser_prism'
   config.example_status_persistence_file_path = 'spec/examples.txt'
   config.disable_monkey_patching!
   config.warnings = true