[libcxx-commits] [libcxx] [libc++] Provide sized deallocation declarations even when the compiler doesn't support sized deallocation (PR #125577)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libcxx

Author: Louis Dionne (ldionne)

<details>
<summary>Changes</summary>

After ef804d8f9b4, we stopped providing the declaration of sized deallocation functions unless the compiler provides support for the language feature. In reality, we can still provide the declarations of global operator delete for users who want to call these operators directly without going through the compiler rewrite.

---
Full diff: https://github.com/llvm/llvm-project/pull/125577.diff


2 Files Affected:

- (modified) libcxx/include/__new/global_new_delete.h (+1-1) 
- (added) libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/sized_delete.fno-sized-deallocation.pass.cpp (+27) 


``````````diff
diff --git a/libcxx/include/__new/global_new_delete.h b/libcxx/include/__new/global_new_delete.h
index 96510ab56b00b5a..3d1f7b6f3d24090 100644
--- a/libcxx/include/__new/global_new_delete.h
+++ b/libcxx/include/__new/global_new_delete.h
@@ -25,7 +25,7 @@
 #  define _THROW_BAD_ALLOC
 #endif
 
-#if defined(__cpp_sized_deallocation) && __cpp_sized_deallocation >= 201309L
+#if _LIBCPP_STD_VER >= 14
 #  define _LIBCPP_HAS_SIZED_DEALLOCATION 1
 #else
 #  define _LIBCPP_HAS_SIZED_DEALLOCATION 0
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/sized_delete.fno-sized-deallocation.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/sized_delete.fno-sized-deallocation.pass.cpp
new file mode 100644
index 000000000000000..daa0374fd28125d
--- /dev/null
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/sized_delete.fno-sized-deallocation.pass.cpp
@@ -0,0 +1,27 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Ensure that libc++ still provides the declaration of sized operator delete even
+// when sized deallocation support is disabled at the language level, since it should
+// still be valid to call these operators explicitly (as opposed to via a compiler
+// rewrite of a delete expression).
+
+// UNSUPPORTED: c++03, c++11
+
+// ADDITIONAL_COMPILE_FLAGS: -fno-sized-deallocation
+
+// Sized deallocation support was introduced in LLVM 11
+// XFAIL: using-built-library-before-llvm-11
+
+#include <new>
+
+int main(int, char**) {
+    void* p = ::operator new(10);
+    ::operator delete(p, 10);
+    return 0;
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/125577