Handle comments and blank interpolations in regexp parsed_tree (#8803)

* Handle comments and blank interpolations in regexp parsed_tree

CHANGELOG.md

@@ -14,6 +14,7 @@
 
 ### Changes
 
+* [#8803](https://github.com/rubocop-hq/rubocop/pull/8803): **(Breaking)** `RegexpNode#parsed_tree` now processes regexps including interpolation (by blanking the interpolation before parsing, rather than skipping). ([@owst][])
 * [#8646](https://github.com/rubocop-hq/rubocop/issues/8646): Faster find of all files in `TargetFinder` class which improves initial startup speed. ([@tleish][])
 * [#8102](https://github.com/rubocop-hq/rubocop/issues/8102): Consider class length instead of block length for `Struct.new`. ([@tejasbubane][])
 

lib/rubocop/cop/lint/mixed_regexp_capture_types.rb

@@ -25,6 +25,7 @@ class MixedRegexpCaptureTypes < Base
               'in a Regexp literal.'
 
         def on_regexp(node)
+          return if node.interpolation?
           return if node.each_capture(named: false).none?
           return if node.each_capture(named: true).none?
 

lib/rubocop/ext/regexp_node.rb

@@ -17,11 +17,9 @@ class << self
 
       # @return [Regexp::Expression::Root, nil]
       def parsed_tree
-        return if interpolation?
-
-        str = content
+        str = with_interpolations_blanked
         Ext::RegexpNode.parsed_cache[str] ||= begin
-          Regexp::Parser.parse(str)
+          Regexp::Parser.parse(str, options: options)
         rescue StandardError
           nil
         end
@@ -40,6 +38,24 @@ def each_capture(named: ANY)
         self
       end
 
+      private
+
+      def with_interpolations_blanked
+        # Ignore the trailing regopt node
+        children[0...-1].map do |child|
+          source = child.source
+
+          # We don't want to consider the contents of interpolations as part of the pattern source,
+          # but need to preserve their width, to allow offsets to correctly line up with the
+          # original source: spaces have no effect, and preserve width.
+          if child.begin_type?
+            ' ' * source.length
+          else
+            source
+          end
+        end.join
+      end
+
       AST::RegexpNode.include self
     end
   end

rubocop.gemspec

@@ -36,9 +36,9 @@ Gem::Specification.new do |s|
   s.add_runtime_dependency('parallel', '~> 1.10')
   s.add_runtime_dependency('parser', '>= 2.7.1.5')
   s.add_runtime_dependency('rainbow', '>= 2.2.2', '< 4.0')
-  s.add_runtime_dependency('regexp_parser', '>= 1.7')
+  s.add_runtime_dependency('regexp_parser', '>= 1.8')
   s.add_runtime_dependency('rexml')
-  s.add_runtime_dependency('rubocop-ast', '>= 0.5.0')
+  s.add_runtime_dependency('rubocop-ast', '>= 0.6.0')
   s.add_runtime_dependency('ruby-progressbar', '~> 1.7')
   s.add_runtime_dependency('unicode-display_width', '>= 1.4.0', '< 2.0')
 

spec/rubocop/ext/regexp_node_spec.rb

@@ -32,4 +32,69 @@
       it { is_expected.to match [named] }
     end
   end
+
+  describe '#parsed_tree' do
+    let(:source) { '/foo#{bar}baz/' }
+
+    context 'with an extended mode regexp with comment' do
+      let(:source) { '/42 # the answer/x' }
+
+      it 'returns the expected tree' do
+        tree = node.parsed_tree
+
+        expect(tree.is_a?(Regexp::Expression::Root)).to eq(true)
+        expect(tree.map(&:token)).to eq(%i[literal whitespace comment])
+      end
+    end
+
+    context 'with a regexp containing interpolation' do
+      it 'returns the expected blanked tree' do
+        tree = node.parsed_tree
+
+        expect(tree.is_a?(Regexp::Expression::Root)).to eq(true)
+        expect(tree.to_s).to eq('foo      baz')
+      end
+    end
+
+    context 'with a regexp containing a multi-line interpolation' do
+      let(:source) do
+        <<~'REGEXP'
+          /
+            foo
+            #{
+              bar(
+                42
+              )
+            }
+            baz
+          /
+        REGEXP
+      end
+
+      it 'returns the expected blanked tree' do
+        tree = node.parsed_tree
+
+        expect(tree.is_a?(Regexp::Expression::Root)).to eq(true)
+        expect(tree.to_s.split("\n")).to eq(
+          [
+            '',
+            '  foo',
+            ' ' * 32,
+            '  baz'
+          ]
+        )
+      end
+    end
+
+    context 'with a regexp not containing interpolation' do
+      let(:source) { '/foobaz/' }
+
+      it 'returns the expected tree' do
+        tree = node.parsed_tree
+
+        expect(tree.is_a?(Regexp::Expression::Root)).to eq(true)
+        expect(tree.to_s).to eq('foobaz')
+      end
+    end
+  end
 end