https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92143
Bug ID: 92143
Summary: std::pmr::polymorphic_allocator<char> throws bad_alloc
on macOS
Product: gcc
Version: 9.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: gcc-bugzilla at daryl dot haresign.com
Target Milestone: ---
The following code throws a std::bad_alloc on macOS (seen via GCC 9.2 installed
with Homebrew, on macOS Catalina 10.15):
#include <memory_resource>
#include <string>
int main()
{
std::pmr::string s { "0123456789abcdef" };
}
16 characters is required to get it to overflow SSO.
The same issue can be seen with the following code:
#include <memory_resource>
int main()
{
std::pmr::polymorphic_allocator<char> alloc {
std::pmr::new_delete_resource()
};
alloc.allocate(1);
}
Changing the type from char to short, and char to int, yields the same error.
Once you get to long, it starts working.
Presumably power-of-two alignments less than sizeof(void *) are not supported
(that's certainly what posix_memalign says).
Looking through the wording, it's all down to a question of whether
[mem.res.private] p2 allows for your memory resources to force the alignment to
be at least alignof(void *). I would say the answer is probably yes.
http://eel.is/c++draft/mem.res#private-2
