[libcxx-commits] [libcxx] [libc++] Make libc++ forward-compatible with AppleClang's definition of __builtin_verbose_trap (PR #99529)

[Louis Dionne via libcxx-commits]

https://github.com/ldionne created https://github.com/llvm/llvm-project/pull/99529

AppleClang as included in the Xcode 16 beta implements __builtin_verbose_trap, but it implements slightly different semantics from the ones implemented upstream. This patch makes libc++ compatible with either definition until we drop support for the version of AppleClang that differs from upstream.

>From 13740ee569591dc82ea931a34d1f41347613c5ab Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2 at gmail.com>
Date: Thu, 18 Jul 2024 13:14:17 -0400
Subject: [PATCH] [libc++] Make libc++ forward-compatible with AppleClang's
 definition of __builtin_verbose_trap

AppleClang as included in the Xcode 16 beta implements __builtin_verbose_trap,
but it implements slightly different semantics from the ones implemented
upstream. This patch makes libc++ compatible with either definition until
we drop support for the version of AppleClang that differs from upstream.
---
 libcxx/vendor/llvm/default_assertion_handler.in | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/libcxx/vendor/llvm/default_assertion_handler.in b/libcxx/vendor/llvm/default_assertion_handler.in
index 9bd831c227798..3b6d6b2cca53c 100644
--- a/libcxx/vendor/llvm/default_assertion_handler.in
+++ b/libcxx/vendor/llvm/default_assertion_handler.in
@@ -24,7 +24,13 @@
 #else
 
 #  if __has_builtin(__builtin_verbose_trap)
-#    define _LIBCPP_ASSERTION_HANDLER(message) __builtin_verbose_trap("libc++", message)
+// AppleClang shipped a slightly different version of __builtin_verbose_trap from the upstream
+// version before upstream Clang actually got the builtin.
+#    if defined(_LIBCPP_APPLE_CLANG_VER) && _LIBCPP_APPLE_CLANG_VER < 17000
+#      define _LIBCPP_ASSERTION_HANDLER(message) __builtin_verbose_trap(message)
+#    else
+#      define _LIBCPP_ASSERTION_HANDLER(message) __builtin_verbose_trap("libc++", message)
+#    endif
 #  else
 #    define _LIBCPP_ASSERTION_HANDLER(message) ((void)message, __builtin_trap())
 #  endif