From 6ec4d203f7aaf9737b78b9d90de7865004c900d8 Mon Sep 17 00:00:00 2001
From: yui-knk <spiketeika@gmail.com>
Date: Mon, 1 Jan 2024 10:17:08 +0900
Subject: [PATCH] Warn "literal in condition" for `__LINE__`

Print warning for a code like

```ruby
if __LINE__
end

# => warning: literal in condition
```
---
 parse.y                  | 6 ++++++
 test/ruby/test_syntax.rb | 3 +++
 2 files changed, 9 insertions(+)

diff --git a/parse.y b/parse.y
index 8dd5e470a3..9791d155af 100644
--- a/parse.y
+++ b/parse.y
@@ -14260,6 +14260,12 @@ cond0(struct parser_params *p, NODE *node, enum cond_type type, const YYLTYPE *l
         else {
             SWITCH_BY_COND_TYPE(type, warning, "");
         }
+        break;
+
+      case NODE_LINE:
+        SWITCH_BY_COND_TYPE(type, warning, "");
+        break;
+
       default:
         break;
     }
diff --git a/test/ruby/test_syntax.rb b/test/ruby/test_syntax.rb
index 286a820b02..5e277c8d8e 100644
--- a/test/ruby/test_syntax.rb
+++ b/test/ruby/test_syntax.rb
@@ -1216,6 +1216,9 @@ eom
     assert_warning(/literal in condition/) do
       eval('1 if 1')
     end
+    assert_warning(/literal in condition/) do
+      eval('1 if __LINE__')
+    end
     assert_warning(/symbol literal in condition/) do
       eval('1 if :foo')
     end