https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95825
daniel.klauer at gin dot de changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |daniel.klauer at gin dot de
--- Comment #7 from daniel.klauer at gin dot de ---
Reduced test case:
template<typename T>
struct tc_optional_base
{
// default ctor leaves m_storage uninitialized
tc_optional_base() : m_initialized(false) {}
bool m_initialized;
T m_storage;
};
template<typename T>
tc_optional_base<T> f()
{
return {};
}
tc_optional_base<int> g()
{
return f<int>();
}
$ g++ -Wall -O1 -fsanitize=address b.cxx -c
In function ‘tc_optional_base<T> f() [with T = int]’,
inlined from ‘tc_optional_base<int> g()’ at b.cxx:18:15:
b.cxx:13:17: warning: ‘<anonymous>.tc_optional_base<int>::m_storage’ is used
uninitialized [-Wuninitialized]
13 | return {};
| ^
b.cxx: In function ‘tc_optional_base<int> g()’:
b.cxx:13:17: note: ‘<anonymous>’ declared here
13 | return {};
|
$ g++ --version
g++ (Ubuntu 11.3.0-1ubuntu1~22.04) 11.3.0
It looks like the m_storage field really is uninitialized, although I think in
practice boost::optional does not access it in that state in its implementation
thanks to m_initialized. Does gcc warn about the uninitialized data during
copying of the object here? It does seem to be correct...
In the above case with templates it happens at -O1 already, but without
templates it happens too, at -O2.
