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* [Bug c++/107529] New: constexpr evaluator doesn't check for destroyed objects
@ 2022-11-05 1:04 vanyacpp at gmail dot com
0 siblings, 0 replies; only message in thread
From: vanyacpp at gmail dot com @ 2022-11-05 1:04 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107529
Bug ID: 107529
Summary: constexpr evaluator doesn't check for destroyed
objects
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: vanyacpp at gmail dot com
Target Milestone: ---
I believe this function contains undefined behavior and should not be allowed
to evaluate at compile-time.
The call to `std::destroy_at(p)` should end the lifetime of `*p` and accesses
to `*p` after that should be invalid.
#include <memory>
struct mytype
{
constexpr mytype() : x(42) {}
constexpr ~mytype() {}
int x;
};
constexpr int foo()
{
std::allocator<mytype> alloc;
mytype* p = alloc.allocate(1);
std::construct_at(p);
std::destroy_at(p); // destroy *p
int result = p->x; // access
alloc.deallocate(p, 1);
return result;
}
static_assert(foo() == 42);
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2022-11-05 1:04 [Bug c++/107529] New: constexpr evaluator doesn't check for destroyed objects vanyacpp at gmail dot com
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