[libcxx-commits] [libcxx] [libcxxabi] [libc++][libc++abi] Build with -fsized-deallocation (PR #96217)

[Louis Dionne via libcxx-commits]

https://github.com/ldionne created https://github.com/llvm/llvm-project/pull/96217

This patch makes libc++ and libc++abi build with -fsized-deallocation. That flag is enabled by default in recent versions of Clang, so this patch will make these runtimes forward-compatible with ToT Clang.

>From 77b9ccebda12d8e95f6b78b7e390e37154306933 Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2 at gmail.com>
Date: Thu, 20 Jun 2024 13:31:09 -0400
Subject: [PATCH] [libc++][libc++abi] Build with -fsized-deallocation

This patch makes libc++ and libc++abi build with -fsized-deallocation.
That flag is enabled by default in recent versions of Clang, so this
patch will make these runtimes forward-compatible with ToT Clang.
---
 libcxx/CMakeLists.txt    | 4 ++++
 libcxxabi/CMakeLists.txt | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/libcxx/CMakeLists.txt b/libcxx/CMakeLists.txt
index 4b927017f8c2a..f0946b6022280 100644
--- a/libcxx/CMakeLists.txt
+++ b/libcxx/CMakeLists.txt
@@ -553,6 +553,10 @@ function(cxx_add_basic_build_flags target)
     target_add_compile_flags_if_supported(${target} PRIVATE -fvisibility=hidden)
   endif()
 
+  # Build with -fsized-deallocation, which is default in recent versions of Clang.
+  # TODO(LLVM 21): This can be dropped once we only support Clang >= 19.
+  target_compile_options(${target} PRIVATE -fsized-deallocation)
+
   # Let the library headers know they are currently being used to build the
   # library.
   target_compile_definitions(${target} PRIVATE -D_LIBCPP_BUILDING_LIBRARY)
diff --git a/libcxxabi/CMakeLists.txt b/libcxxabi/CMakeLists.txt
index 52ba52f3439fb..d45b104b41e32 100644
--- a/libcxxabi/CMakeLists.txt
+++ b/libcxxabi/CMakeLists.txt
@@ -247,6 +247,10 @@ endif()
 add_compile_flags("${LIBCXXABI_ADDITIONAL_COMPILE_FLAGS}")
 add_library_flags("${LIBCXXABI_ADDITIONAL_LIBRARIES}")
 
+# Build with -fsized-deallocation, which is default in recent versions of Clang.
+# TODO(LLVM 21): This can be dropped once we only support Clang >= 19.
+add_compile_flags(-fsized-deallocation)
+
 # Configure compiler. Must happen after setting the target flags.
 include(config-ix)