[libcxx-commits] [libcxx] [libc++] Warn when users request a deployment target below the minimum supported version (PR #172664)

[Louis Dionne via libcxx-commits]

================
@@ -196,6 +196,14 @@
     __attribute__((availability(bridgeos, strict, introduced = 6.0)))                                             \
     __attribute__((availability(driverkit, strict, introduced = 21.3)))
 
+#  if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__)  && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__  < 110000) || \
----------------
ldionne wrote:

For now, let's use the versions pinned to macOS 10.13, which is what we document on https://libcxx.llvm.org. I can get them updated after.

```
#  if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__)  && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__  < 101300) || \
      (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 150000) || \
      (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__)     && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__     < 150000) || \
      (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__)  && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__  < 70000)  || \
      (defined(__ENVIRONMENT_DRIVERKIT_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_DRIVERKIT_VERSION_MIN_REQUIRED__ < 190000)
#  warning "The selected platform is no longer supported by libc++."
#  endif
```

https://github.com/llvm/llvm-project/pull/172664