[clang-tools-extra] [clang-tidy] add default error message for performance-avoid-endl (PR #107867)

[Danny Mösch via cfe-commits]

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@@ -225,3 +225,14 @@ void bad_custom_stream() {
   // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: do not use 'std::endl' with streams; use '\n' instead [performance-avoid-endl]
   // CHECK-FIXES: logger << '\n';
 }
+
+namespace gh107859 {
+
+#define ENDL std::endl;
+
+void bad_macro() {
+  std::cout << ENDL;
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SimplyDanny wrote:

But a replacement is always added, isn't it? What am I missing?

https://github.com/llvm/llvm-project/pull/107867