[clang] [clang] Implement __attribute__((format_matches)) (PR #116708)

[via cfe-commits]

================
@@ -292,7 +292,7 @@ class ArgType {
   };
 
 private:
-  const Kind K;
+  Kind K;
----------------
apple-fcloutier wrote:

The `const` field was the only thing that prevented `ArgType` from getting a copy constructor and assignment operators.

https://github.com/llvm/llvm-project/pull/116708