libstdc++: Add align_alloc attribute to aligned operator new

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.

Reviewed-by: Jakub Jelinek <jakub@redhat.com>

diff --git a/libstdc++-v3/libsupc++/new b/libstdc++-v3/libsupc++/new
index e9a3d9b49a3e022d29594d1eb239d07812bcc185..4345030071bbb1fb69fa645ef8b57922d02ba183 100644 (file)
--- 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 (file)
index 0000000..e9d374a
--- /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 *-*-* } }
+}