[clang] Optimize -Wunsafe-buffer-usage. (PR #124554)

[Ilya Biryukov via cfe-commits]

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@@ -79,21 +81,39 @@ static std::string getDREAncestorString(const DeclRefExpr *DRE,
 } // namespace
 #endif /* NDEBUG */
 
-namespace clang::ast_matchers {
+class CustomMatcher {
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ilya-biryukov wrote:

NIT: maybe rename to `FastMatcher`?

We should definitely add a comment explaning why we want this (i.e. we do not use matchers here to achieve better performance).

https://github.com/llvm/llvm-project/pull/124554