[libcxx-commits] [libcxx] [libcxx] changes `__is_allocator` from a struct to a variable or concept (PR #68629)

[Christopher Di Bella via libcxx-commits]

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@@ -57,6 +57,8 @@
     # Disable warnings for extensions used in C++03
     "-Wno-local-type-template-args",
     "-Wno-c++11-extensions",
+    "-Wno-c++14-extensions",
+    "-Wno-c++17-extensions",
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cjdb wrote:

`-isystem` suppresses warnings for the headers it pulls in, so warnings will be suppressed unless we're exposing things via macros (which we aren't currently doing). I certainly wouldn't consider any non-macro exposure of a warning from `-isystem` to be a libc++ bug.

Having said that, this is the sort of test that Clang may want to pass on to libraries to detect. @AaronBallman, any insight here?

https://github.com/llvm/llvm-project/pull/68629