The aligned versions of operator new should use the align_alloc
attribute to help the compiler.
PR c++/86878 requests that the compiler would use the attribute to warn
about invalid attributes, so an XFAILed test is added for that.
libstdc++-v3/ChangeLog:
* libsupc++/new (operator new): Add attribute align_alloc(2) to
overloads taking a std::align_val_t argument.
* testsuite/18_support/new_aligned_warn.cc: New test.
---
I think this makes sense, but maybe there's some property of the
attribute that means this isn't a good idea? I think the compiler can
use the value of align_val_t even though it's a scoped enumeration type.
Tested x86_64-linux.
libstdc++-v3/libsupc++/new | 6 +++---
.../testsuite/18_support/new_aligned_warn.cc | 13 +++++++++++++
2 files changed, 16 insertions(+), 3 deletions(-)
create mode 100644 libstdc++-v3/testsuite/18_support/new_aligned_warn.cc
diff --git a/libstdc++-v3/libsupc++/new b/libstdc++-v3/libsupc++/new
index e9a3d9b49a3..4345030071b 100644
--- a/libstdc++-v3/libsupc++/new
+++ b/libstdc++-v3/libsupc++/new
@@ -167,7 +167,7 @@ void operator delete[](void*, const std::nothrow_t&)
#if __cpp_aligned_new
_GLIBCXX_NODISCARD void* operator new(std::size_t, std::align_val_t)
_GLIBCXX_TXN_SAFE
- __attribute__((__externally_visible__, __alloc_size__ (1), __malloc__));
+ __attribute__((__externally_visible__, __alloc_size__ (1), __alloc_align__
(2), __malloc__));
_GLIBCXX_NODISCARD void* operator new(std::size_t, std::align_val_t, const
std::nothrow_t&)
_GLIBCXX_TXN_SAFE
_GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__, __alloc_size__
(1), __malloc__));
@@ -178,10 +178,10 @@ void operator delete(void*, std::align_val_t, const
std::nothrow_t&)
_GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
_GLIBCXX_NODISCARD void* operator new[](std::size_t, std::align_val_t)
_GLIBCXX_TXN_SAFE
- __attribute__((__externally_visible__, __alloc_size__ (1), __malloc__));
+ __attribute__((__externally_visible__, __alloc_size__ (1), __alloc_align__
(2), __malloc__));
_GLIBCXX_NODISCARD void* operator new[](std::size_t, std::align_val_t, const
std::nothrow_t&)
_GLIBCXX_TXN_SAFE
- _GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__, __alloc_size__
(1), __malloc__));
+ _GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__, __alloc_size__
(1), __alloc_align__ (2), __malloc__));
void operator delete[](void*, std::align_val_t) _GLIBCXX_TXN_SAFE
_GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
void operator delete[](void*, std::align_val_t, const std::nothrow_t&)
diff --git a/libstdc++-v3/testsuite/18_support/new_aligned_warn.cc
b/libstdc++-v3/testsuite/18_support/new_aligned_warn.cc
new file mode 100644
index 00000000000..e9d374abe31
--- /dev/null
+++ b/libstdc++-v3/testsuite/18_support/new_aligned_warn.cc
@@ -0,0 +1,13 @@
+// { dg-options "-Wattributes" }
+// { dg-do compile { target c++17 } }
+
+#include <new>
+
+int main()
+{
+ // PR c++/86878 has a patch to make these warn.
+ (void) operator new(1, std::align_val_t(3)); // { dg-warning "power of two"
"" { xfail *-*-* } }
+ (void) operator new[](1, std::align_val_t(10)); // { dg-warning "power of
two" "" { xfail *-*-* } }
+ (void) operator new(1, std::align_val_t(0), std::nothrow_t()); // {
dg-warning "power of two" "" { xfail *-*-* } }
+ (void) operator new[](1, std::align_val_t(-1), std::nothrow_t()); // {
dg-warning "power of two" "" { xfail *-*-* } }
+}
--
2.47.0
