[libcxx-commits] [libcxx] [libc++] Introduce the notion of a minimum header version (PR #166074)

[Louis Dionne via libcxx-commits]

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@@ -11,6 +11,7 @@
 
 #cmakedefine _LIBCPP_ABI_VERSION @_LIBCPP_ABI_VERSION@
 #cmakedefine _LIBCPP_ABI_NAMESPACE @_LIBCPP_ABI_NAMESPACE@
+#cmakedefine _LIBCPP_AVAILABILITY_MINIMUM_HEADER_VERSION @_LIBCPP_AVAILABILITY_MINIMUM_HEADER_VERSION@
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ldionne wrote:

Per our discussion just now, I think we shouldn't encode this in the `__config_site`. Indeed, this is persistent configuration state that only pertains to the dylib build, and it shouldn't be possible to access this information outside of the dylib build. Doing otherwise is necessarily a misuse of this "configuration variable".

https://github.com/llvm/llvm-project/pull/166074