Recover Ruby 2.0 code analysis using TargetRubyVersion: 2.0

Follow up rubocop#10632 (comment).

Reverts part of rubocop#4787.

Only the Ruby version (2.0) to runtime should have been dropped, not code analysis.
This PR makes Ruby 2.0 code analysis with `TargetRubyVersion: 2.0`.
It aims to solve essentially the same problem as rubocop#10626, rubocop#10632, rubocop#10640, rubocop#10644, and rubocop#10662.

changelog/fix_recover_ruby_20_code_analysis.md

@@ -0,0 +1 @@
+* [#10668](https://github.com/rubocop/rubocop/pull/10668): Recover Ruby 2.0 code analysis using `TargetRubyVersion: 2.0`. ([@koic][])

lib/rubocop/cop/style/dir.rb

@@ -18,6 +18,9 @@ module Style
       #   path = __dir__
       class Dir < Base
         extend AutoCorrector
+        extend TargetRubyVersion
+
+        minimum_target_ruby_version 2.0
 
         MSG = "Use `__dir__` to get an absolute path to the current file's directory."
         RESTRICT_ON_SEND = %i[expand_path dirname].freeze

lib/rubocop/cop/style/symbol_array.rb

@@ -7,7 +7,8 @@ module Style
       # using the %i() syntax.
       #
       # Alternatively, it checks for symbol arrays using the %i() syntax on
-      # projects which do not want to use that syntax.
+      # projects which do not want to use that syntax, perhaps because they
+      # support a version of Ruby lower than 2.0.
       #
       # Configuration option: MinSize
       # If set, arrays with fewer elements than this value will not trigger the
@@ -33,6 +34,9 @@ class SymbolArray < Base
         include ConfigurableEnforcedStyle
         include PercentArray
         extend AutoCorrector
+        extend TargetRubyVersion
+
+        minimum_target_ruby_version 2.0
 
         PERCENT_MSG = 'Use `%i` or `%I` for an array of symbols.'
         ARRAY_MSG = 'Use `%<prefer>s` for an array of symbols.'

lib/rubocop/rspec/shared_contexts.rb

@@ -116,6 +116,10 @@ def source_range(range, buffer: source_buffer)
   end
 end
 
+RSpec.shared_context 'ruby 2.0', :ruby20 do
+  let(:ruby_version) { 2.0 }
+end
+
 RSpec.shared_context 'ruby 2.1', :ruby21 do
   let(:ruby_version) { 2.1 }
 end

lib/rubocop/target_ruby.rb

@@ -4,7 +4,7 @@ module RuboCop
   # The kind of Ruby that code inspected by RuboCop is written in.
   # @api private
   class TargetRuby
-    KNOWN_RUBIES = [2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 3.0, 3.1, 3.2].freeze
+    KNOWN_RUBIES = [2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 3.0, 3.1, 3.2].freeze
     DEFAULT_VERSION = 2.6
 
     OBSOLETE_RUBIES = {

spec/rubocop/cli_spec.rb

@@ -1724,7 +1724,7 @@ def method(foo, bar, qux, fred, arg5, f) end #{'#' * 85}
           'Error: RuboCop found unknown Ruby version 4.0 in `TargetRubyVersion`'
         )
         expect($stderr.string.strip).to match(
-          /Supported versions: 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 3.0, 3.1, 3.2/
+          /Supported versions: 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 3.0, 3.1, 3.2/
         )
       end
     end
@@ -1733,20 +1733,20 @@ def method(foo, bar, qux, fred, arg5, f) end #{'#' * 85}
       it 'fails with an error message' do
         create_file('.rubocop.yml', <<~YAML)
           AllCops:
-            TargetRubyVersion: 2.0
+            TargetRubyVersion: 1.9
         YAML
 
         expect(cli.run([])).to eq(2)
         expect($stderr.string.strip).to start_with(
-          'Error: RuboCop found unsupported Ruby version 2.0 in '\
+          'Error: RuboCop found unsupported Ruby version 1.9 in '\
           '`TargetRubyVersion`'
         )
 
         expect($stderr.string.strip).to match(
-          /2\.0-compatible analysis was dropped after version 0\.50/
+          /1\.9-compatible analysis was dropped after version 0\.41/
         )
 
-        expect($stderr.string.strip).to match(/Supported versions: 2.1/)
+        expect($stderr.string.strip).to match(/Supported versions: 2.0/)
       end
     end
   end

spec/rubocop/config_loader_spec.rb

@@ -1188,7 +1188,7 @@ class Loop < Base
       end
 
       context 'when the specified version is obsolete' do
-        let(:inherited_version) { '2.0' }
+        let(:inherited_version) { '1.9' }
 
         context 'and it is not overridden' do
           before do
@@ -1199,7 +1199,7 @@ class Loop < Base
 
           it 'raises a validation error' do
             expect { configuration_from_file }.to raise_error(RuboCop::ValidationError) do |error|
-              expect(error.message).to start_with('RuboCop found unsupported Ruby version 2.0')
+              expect(error.message).to start_with('RuboCop found unsupported Ruby version 1.9')
             end
           end
         end

spec/rubocop/cop/style/optional_arguments_spec.rb

@@ -71,7 +71,7 @@ def foo(a = 1, b: 2)
       end
     end
 
-    context 'required params' do
+    context 'required params', :ruby21 do
       it 'registers an offense for optional arguments that come before ' \
          'required arguments where there are name arguments' do
         expect_offense(<<~RUBY)