[clang-tools-extra] [clang-tidy] Fix loading clang-tidy as a Clang frontend plugin (PR #221961)

[Zeyi Xu via cfe-commits]

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@@ -8,10 +8,16 @@
 
 #include "../ClangTidy.h"
 #include "../ClangTidyDiagnosticConsumer.h"
+#include "../ClangTidyForceLinker.h" // IWYU pragma: keep
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zeyi2 wrote:

This header ensures the built-in checks are linked into the plugin and registered. It was removed as an unused include in #141420, breaking check registration in the plugin.

https://github.com/llvm/llvm-project/pull/221961