Bug#1085524: gcc-12: Please upgrade Debian 12's GCC version to 12.4

[cnbatch <cnbatch@gmail.com>]

Package: gcc-12
Version: 12.2.0-14
Severity: normal
X-Debbugs-Cc: cnbatch@gmail.com

Dear Maintainer,

The following C++20 code can be compiled with GCC 12.3 or later but can't be compiled on Debian 12 with GCC 12.2:

```
#include <atomic>
#include <memory>

class A{ int a; };

int main()
{
    std::atomic<std::shared_ptr<A>> a_ptr = std::make_shared<A>();
    a_ptr = nullptr;

    return 0;
}
```

Error Messages:
```
test.cpp: In function ‘int main()’:
test.cpp:9:13: error: ambiguous overload for ‘operator=’ (operand types are ‘std::atomic<std::shared_ptr<A> >’ and ‘std::nullptr_t’)
    9 |     a_ptr = nullptr;
      |             ^~~~~~~
In file included from /usr/include/c++/12/memory:78,
                 from test.cpp:2:
/usr/include/c++/12/bits/shared_ptr_atomic.h:585:12: note: candidate: ‘void std::atomic<std::shared_ptr<_Tp> >::operator=(const std::atomic<std::shared_ptr<_Tp> >&) [with _Tp = A]’ (deleted)
  585 |       void operator=(const atomic&) = delete;
      |            ^~~~~~~~
/usr/include/c++/12/bits/shared_ptr_atomic.h:600:7: note: candidate: ‘void std::atomic<std::shared_ptr<_Tp> >::operator=(std::shared_ptr<_Tp>) [with _Tp = A]’
  600 |       operator=(shared_ptr<_Tp> __desired) noexcept
      |       ^~~~~~~~
```

This may be a bug of GCC 12.2, please upgrade GCC version of Debian 12.


-- System Information:
Debian Release: 12.7
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable-security'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 6.1.0-26-amd64 (SMP w/12 CPU threads; PREEMPT)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages gcc-12 depends on:
ii  binutils       2.40-2
ii  cpp-12         12.2.0-14
ii  gcc-12-base    12.2.0-14
ii  libc6          2.36-9+deb12u8
ii  libcc1-0       12.2.0-14
ii  libgcc-12-dev  12.2.0-14
ii  libgcc-s1      12.2.0-14
ii  libgmp10       2:6.2.1+dfsg1-1.1
ii  libisl23       0.25-1.1
ii  libmpc3        1.3.1-1
ii  libmpfr6       4.2.0-1
ii  libstdc++6     12.2.0-14
ii  libzstd1       1.5.4+dfsg2-5
ii  zlib1g         1:1.2.13.dfsg-1

Versions of packages gcc-12 recommends:
ii  libc6-dev  2.36-9+deb12u8

Versions of packages gcc-12 suggests:
pn  gcc-12-doc       <none>
pn  gcc-12-locales   <none>
pn  gcc-12-multilib  <none>

-- no debconf information