[clang-tools-extra] [clang-tidy] support query based custom check (PR #131804)

[Baranov Victor via cfe-commits]

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@@ -0,0 +1,50 @@
+#include "../ClangTidy.h"
+#include "../ClangTidyModule.h"
+#include "../ClangTidyModuleRegistry.h"
+#include "../ClangTidyOptions.h"
+#include "QueryCheck.h"
+#include "llvm/ADT/SmallSet.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/StringRef.h"
+#include <memory>
+
+namespace clang::tidy {
+namespace custom {
+
+class CustomModule : public ClangTidyModule {
+public:
+  void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override {}
+};
+
+// We need to register the checks more flexibly than builtin modules. The checks
+// will changed dynamically when switching to different source file.
+extern void registerCustomChecks(ClangTidyOptions const &Options,
+                                 ClangTidyCheckFactories &Factories) {
+  static llvm::SmallSet<llvm::SmallString<32>, 8> CustomCheckNames{};
+  if (!Options.CustomChecks.has_value() || Options.CustomChecks->empty())
+    return;
+  for (llvm::SmallString<32> const &Name : CustomCheckNames)
+    Factories.erase(Name);
+  for (const ClangTidyOptions::CustomCheckValue &V :
+       Options.CustomChecks.value()) {
+    llvm::SmallString<32> Name = llvm::StringRef{"custom-" + V.Name};
+    Factories.registerCheckFactory(
+        // add custom- prefix to avoid conflicts with builtin checks
+        Name, [&V](llvm::StringRef Name, ClangTidyContext *Context) {
+          return std::make_unique<custom::QueryCheck>(Name, V, Context);
+        });
+    CustomCheckNames.insert(std::move(Name));
+  }
+}
+
+} // namespace custom
+
+// Register the AlteraTidyModule using this statically initialized variable.
----------------
vbvictor wrote:

```suggestion
// Register the CustomTidyModule using this statically initialized variable.
```
or delete this comment at all

https://github.com/llvm/llvm-project/pull/131804