[clang-tools-extra] [clang-tidy][NFC] optimize cache for config option (PR #121406)

[Julian Schmidt via cfe-commits]

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@@ -337,33 +337,34 @@ FileOptionsBaseProvider::FileOptionsBaseProvider(
 void FileOptionsBaseProvider::addRawFileOptions(
     llvm::StringRef AbsolutePath, std::vector<OptionsSource> &CurOptions) {
   auto CurSize = CurOptions.size();
-
   // Look for a suitable configuration file in all parent directories of the
   // file. Start with the immediate parent directory and move up.
-  StringRef Path = llvm::sys::path::parent_path(AbsolutePath);
-  for (StringRef CurrentPath = Path; !CurrentPath.empty();
-       CurrentPath = llvm::sys::path::parent_path(CurrentPath)) {
-    std::optional<OptionsSource> Result;
-
-    auto Iter = CachedOptions.find(CurrentPath);
-    if (Iter != CachedOptions.end())
-      Result = Iter->second;
-
-    if (!Result)
-      Result = tryReadConfigFile(CurrentPath);
-
-    if (Result) {
-      // Store cached value for all intermediate directories.
-      while (Path != CurrentPath) {
+  StringRef RootPath = llvm::sys::path::parent_path(AbsolutePath);
+  auto MemorizedConfigFile =
+      [this, &RootPath](StringRef CurrentPath) -> std::optional<OptionsSource> {
+    auto Iter = CachedOptions.Memorized.find(CurrentPath);
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5chmidti wrote:

nit: can be `const`, and can be declared as the if-init var to reduce its scope

https://github.com/llvm/llvm-project/pull/121406