[libcxx] [llvm] [RFC][libc++] Reworks clang-tidy selection. (PR #81362)

[Louis Dionne via llvm-commits]

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@@ -5,10 +5,10 @@
 set(LLVM_DIR_SAVE ${LLVM_DIR})
 set(Clang_DIR_SAVE ${Clang_DIR})
 
-find_package(Clang 18)
-if (NOT Clang_FOUND)
-  find_package(Clang 17)
-endif()
+# Since the Clang C++ ABI is not stable the Clang libraries and clang-tidy
+# version must match. Otherwise there likely will be ODR-violations. This had
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ldionne wrote:

```suggestion
# versions must match. Otherwise there likely will be ODR-violations. This had
```

https://github.com/llvm/llvm-project/pull/81362