https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111258
Jiang An <de34 at live dot cn> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |de34 at live dot cn
--- Comment #2 from Jiang An <de34 at live dot cn> ---
Perhaps this is a compiler bug and there's nothing wrong in the move
constructor.
GCC 13 also incorrectly rejects the following program
(https://godbolt.org/z/Yn98KMKv5)
```
#include <string>
constexpr bool foo11(std::string s)
{
s.push_back('\0');
return true;
}
int main()
{
static_assert(foo11(std::string{}));
}
```
with similar message:
```
<source>: In function 'int main()':
<source>:12:24: error: non-constant condition for static assertion
12 | static_assert(foo11(std::string{}));
| ~~~~~^~~~~~~~~~~~~~~
<source>:12:24: in 'constexpr' expansion of
'foo11(std::__cxx11::basic_string<char>())'
<source>:5:16: in 'constexpr' expansion of
's.std::__cxx11::basic_string<char>::push_back(0)'
/opt/compiler-explorer/gcc-13.2.0/include/c++/13.2.0/bits/basic_string.h:1552:33:
in 'constexpr' expansion of
'((std::__cxx11::basic_string<char>*)this)->std::__cxx11::basic_string<char>::capacity()'
<source>:12:24: error: accessing 'std::__cxx11::basic_string<char>::<unnamed
union>::_M_allocated_capacity' member instead of initialized
'std::__cxx11::basic_string<char>::<unnamed union>::_M_local_buf' member in
constant expression
Compiler returned: 1
```
It seems that gcc currently miscompiles passing-by-value of
non-trivially-copyable classes in constant evaluation.
