[libcxx-commits] [libcxx] [libc++][hardening] Rework how the assertion handler can be overridden. (PR #77883)

[Konstantin Varlamov via libcxx-commits]

================
@@ -69,6 +69,13 @@ if (NOT "${LIBCXX_HARDENING_MODE}" IN_LIST LIBCXX_SUPPORTED_HARDENING_MODES)
   message(FATAL_ERROR
     "Unsupported hardening mode: '${LIBCXX_HARDENING_MODE}'. Supported values are ${LIBCXX_SUPPORTED_HARDENING_MODES}.")
 endif()
+set(LIBCXX_ASSERTION_HANDLER_FILE
+  "${CMAKE_CURRENT_SOURCE_DIR}/vendor/llvm/default_assertion_handler.in"
+  CACHE STRING
+  "Specify the path to a header that contains a custom implementation of the
+   assertion handler that gets invoked when a hardening assertion fails. If
+   provided, the contents of this header will get injected into the library code
+   and override the default assertion handler.")
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var-const wrote:

@mordante After writing this, I realized that we can just as well do something like:
```cpp
#ifndef _LIBCPP_ASSERTION_HANDLER
#include "__custom_assertion_handler.h"
#endif
```
which alleviates my concern. In fact, I think both approaches have equal expressive power and are not visible to the user/vendor. I think they're very similar, but having a single header seems to be a little simpler/cleaner, so I'll give it a shot based on your suggestion.

https://github.com/llvm/llvm-project/pull/77883