[Fix rubocop#10755] Fix a false positive for Lint/LiteralAsCondition

Fixes rubocop#10755.

This PR fixes a false positive for `Lint/LiteralAsCondition`
when using a literal in `case-in` condition where the match variable is used in
`in` are accepted as a pattern matching.

changelog/fix_a_false_positive_for_lint_literal_as_condition.md

@@ -0,0 +1 @@
+* [#10755](https://github.com/rubocop/rubocop/issues/10755): Fix a false positive for `Lint/LiteralAsCondition` when using a literal in `case-in` condition where the match variable is used in `in` are accepted as a pattern matching. ([@koic][])

lib/rubocop/cop/lint/literal_as_condition.rb

@@ -7,6 +7,9 @@ module Lint
       # operands in and/or expressions serving as the conditions of
       # if/while/until/case-when/case-in.
       #
+      # NOTE: Literals in `case-in` condition where the match variable is used in
+      # `in` are accepted as a pattern matching.
+      #
       # @example
       #
       #   # bad
@@ -69,6 +72,8 @@ def on_case(case_node)
 
         def on_case_match(case_match_node)
           if case_match_node.condition
+            return if case_match_node.descendants.any?(&:match_var_type?)
+
             check_case(case_match_node)
           else
             case_match_node.each_in_pattern do |in_pattern_node|

spec/rubocop/cop/lint/literal_as_condition_spec.rb

@@ -75,11 +75,19 @@
     end
 
     context '>= Ruby 2.7', :ruby27 do
-      it "registers an offense for literal #{lit} in case match" do
+      it "accepts an offense for literal #{lit} in case match with a match var" do
+        expect_no_offenses(<<~RUBY, lit: lit)
+          case %{lit}
+          in x then top
+          end
+        RUBY
+      end
+
+      it "registers an offense for literal #{lit} in case match without a match var" do
         expect_offense(<<~RUBY, lit: lit)
           case %{lit}
                ^{lit} Literal `#{lit}` appeared as a condition.
-          in x then top
+          in CONST then top
           end
         RUBY
       end
@@ -219,6 +227,14 @@
       RUBY
     end
 
+    it 'accepts an offense for case match with a match var' do
+      expect_no_offenses(<<~RUBY)
+        case { a: 1, b: 2, c: 3 }
+        in a: Integer => m
+        end
+      RUBY
+    end
+
     it 'accepts dstr literal in case match' do
       expect_no_offenses(<<~'RUBY')
         case "#{x}"