Avoid unnecessary parentheses when autocorrecting bracket access

lib/rubocop/cop/type_toolkit/prefer_not_nil.rb

@@ -81,6 +81,7 @@ def requires_parentheses?(argument)
           return false if argument.begin_type?
 
           if argument.is_a?(RuboCop::AST::SendNode)
+            return bracket_call_requires_parentheses?(argument) if argument.method?(:[])
             return true if argument.operator_method?
             return true if argument.arguments? && !argument.parenthesized_call?
           end
@@ -90,6 +91,12 @@ def requires_parentheses?(argument)
 
           KEYWORD_EXPRESSION_TYPES.include?(argument.type)
         end
+
+        # `foo[bar]` and `foo.[](bar)` can be chained directly, but command-style `foo.[] bar` cannot.
+        #: (RuboCop::AST::SendNode) -> bool
+        def bracket_call_requires_parentheses?(argument)
+          argument.dot? && !argument.parenthesized_call?
+        end
       end
     end
   end

spec/rubocop/cop/type_toolkit/prefer_not_nil_spec.rb

@@ -134,6 +134,23 @@ def explicit_super
           RUBY
         end
 
+        it "parenthesizes bracket method calls only when required" do
+          assert_offense(<<~RUBY)
+            bracketed = T.must(foo[bar]).foo
+                        ^^^^^^^^^^^^^^^^ #{MSG}
+            explicit = T.must(foo.[](bar)).foo
+                       ^^^^^^^^^^^^^^^^^^^ #{MSG}
+            command = T.must(foo.[] bar).foo
+                      ^^^^^^^^^^^^^^^^^^ #{MSG}
+          RUBY
+
+          assert_correction(<<~RUBY)
+            bracketed = foo[bar].not_nil!.foo
+            explicit = foo.[](bar).not_nil!.foo
+            command = (foo.[] bar).not_nil!.foo
+          RUBY
+        end
+
         it "preserves comments in multiline calls" do
           assert_offense(<<~RUBY)
             value = T.must(