[clang-tools-extra] [clang-tidy] Fix broken HeaderFilterRegex when read from config file (PR #133582)

[Congcong Cai via cfe-commits]

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@@ -571,17 +560,30 @@ void ClangTidyDiagnosticConsumer::checkFilters(SourceLocation Location,
   }
 
   StringRef FileName(File->getName());
-  LastErrorRelatesToUserCode =
-      LastErrorRelatesToUserCode || Sources.isInMainFile(Location) ||
-      (HeaderFilter &&
-       (HeaderFilter->match(FileName) &&
-        !(ExcludeHeaderFilter && ExcludeHeaderFilter->match(FileName))));
+  LastErrorRelatesToUserCode = LastErrorRelatesToUserCode ||
+                               Sources.isInMainFile(Location) ||
+                               (getHeaderFilter()->match(FileName) &&
+                                !getExcludeHeaderFilter()->match(FileName));
 
   unsigned LineNumber = Sources.getExpansionLineNumber(Location);
   LastErrorPassesLineFilter =
       LastErrorPassesLineFilter || passesLineFilter(FileName, LineNumber);
 }
 
+llvm::Regex *ClangTidyDiagnosticConsumer::getHeaderFilter() {
+  if (!HeaderFilter)
+    HeaderFilter =
+        std::make_unique<llvm::Regex>(*Context.getOptions().HeaderFilterRegex);
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HerrCai0907 wrote:

HeaderFilterRegex is `std::optional<>`. How to handle `HeaderFilterRegex` is `std::nullopt`?

https://github.com/llvm/llvm-project/pull/133582