[libc++] Avoid relying on non-portable behaviour in std::align
Round-tripping pointers via size_t is not portable, the C/C++ standards
only require this to be valid when using (u)intptr_t.
Originally committed to the CHERI fork of LLVM as
https://github.com/CTSRD-CHERI/llvm-project/commit/dd01245185ab9e71b70b418bee8f11ea0199e1a3,
but I forgot to upstream the change. I rediscovered this issue due to a
compiler warning when building libc++ on a Arm Morello system.
Reviewed By: #libc, ldionne, philnik
Differential Revision: https://reviews.llvm.org/D134363
NOKEYCHECK=True
GitOrigin-RevId: 0a893cfb44e7d18296d6a7aff1ad11e615a89e93
diff --git a/src/memory.cpp b/src/memory.cpp
index 2dcbb35..3fd5439 100644
--- a/src/memory.cpp
+++ b/src/memory.cpp
@@ -194,7 +194,7 @@
if (size <= space)
{
char* p1 = static_cast<char*>(ptr);
- char* p2 = reinterpret_cast<char*>(reinterpret_cast<size_t>(p1 + (alignment - 1)) & -alignment);
+ char* p2 = reinterpret_cast<char*>(reinterpret_cast<uintptr_t>(p1 + (alignment - 1)) & -alignment);
size_t d = static_cast<size_t>(p2 - p1);
if (d <= space - size)
{