[clang-tools-extra] [clang-tidy][NFC] Don't store a redundant copy of `HeaderFileExtensions` in every check (PR #190302)

[Victor Chernyakin via cfe-commits]

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@@ -480,6 +480,16 @@ class ClangTidyCheck : public ast_matchers::MatchFinder::MatchCallback {
     ClangTidyContext *Context;
   };
 
+  /// Returns the list of header file extensions from the context.
+  const FileExtensionsSet &getHeaderFileExtensions() const {
+    return Context->getHeaderFileExtensions();
+  }
+
+  /// Returns the list of implementation file extensions from the context.
+  const FileExtensionsSet &getImplementationFileExtensions() const {
+    return Context->getImplementationFileExtensions();
+  }
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localspook wrote:

These getters are public, *unlike* the existing getters below, which are protected. I made them public because `bugprone-suspicious-include` defines a `PPCallbacks` which wants to call them. I don't see a problem with making them (or even the existing ones) public, but maybe someone does?

https://github.com/llvm/llvm-project/pull/190302