https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110714
Bug ID: 110714
Summary: constexpr lifetime error: base class this pointer
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: pkeir at outlook dot com
Target Milestone: ---
Compiling the C++20 MRE code below fails:
struct Base
{
constexpr virtual ~Base() {}
constexpr Base* get_this() { return this; }
int x;
};
struct Derived : public Base {};
constexpr bool test()
{
Derived* pf = new Derived;
delete pf->get_this();
return true;
}
constexpr bool b = test();
...with the following error message:
2$ /opt/gcc-latest/bin/g++ -std=c++20 -c ce_base_alloc2.cpp
ce_base_alloc2.cpp:17:24: in ‘constexpr’ expansion of ‘test()’
ce_base_alloc2.cpp:13:23: in ‘constexpr’ expansion of
‘pf->Derived::<anonymous>.Base::get_this()->Base::~Base()’
ce_base_alloc2.cpp:8:8: error: deallocation of storage that was not previously
allocated
8 | struct Derived : public Base {};
| ^~~~~~~
I have tried with GCC trunk (14.0.0) and also version 12.2.0.
I suspect that the this pointer in the base class is not tracking the constexpr
dynamic allocation. Clang and MSVC both compile successfully. Clang requires
the virtual destructor.
