[Fix #10002] Fix an incorrect auto-correct for Lint/AmbigousRegexpLiteral

changelog/fix_incorrect_autocorrect_for_lint_ambiguous_regexp_literal.md

@@ -0,0 +1 @@
+* [#10002](https://github.com/rubocop/rubocop/issues/10002): Fix an incorrect auto-correct for `Lint/AmbigousRegexpLiteral` when using nested method arguments without parentheses. ([@koic][])

lib/rubocop/cop/lint/ambiguous_regexp_literal.rb

@@ -46,12 +46,11 @@ def find_offense_node_by(diagnostic)
           node = processed_source.ast.each_node(:regexp).find do |regexp_node|
             regexp_node.source_range.begin_pos == diagnostic.location.begin_pos
           end
-
           find_offense_node(node.parent, node)
         end
 
         def find_offense_node(node, regexp_receiver)
-          return node unless node.parent
+          return node if first_argument_is_regexp?(node) || !node.parent
 
           if (node.parent.send_type? && node.receiver) ||
              method_chain_to_regexp_receiver?(node, regexp_receiver)
@@ -61,6 +60,10 @@ def find_offense_node(node, regexp_receiver)
           node
         end
 
+        def first_argument_is_regexp?(node)
+          node.send_type? && node.first_argument&.regexp_type?
+        end
+
         def method_chain_to_regexp_receiver?(node, regexp_receiver)
           return false unless (parent = node.parent)
           return false unless (parent_receiver = parent.receiver)

spec/rubocop/cop/lint/ambiguous_regexp_literal_spec.rb

@@ -127,6 +127,17 @@ class MyTest
           end
         RUBY
       end
+
+      it 'registers an offense and corrects when using nested method arguments without parentheses' do
+        expect_offense(<<~RUBY)
+          puts line.grep /pattern/
+                         ^ Ambiguous regexp literal. Parenthesize the method arguments if it's surely a regexp literal, or add a whitespace to the right of the `/` if it should be a division.
+        RUBY
+
+        expect_correction(<<~RUBY)
+          puts line.grep(/pattern/)
+        RUBY
+      end
     end
 
     context 'with parentheses' do