https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107206
Bug ID: 107206
Summary: Bogus -Wuninitialized in std::optional
Product: gcc
Version: 12.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: ed at catmur dot uk
Target Milestone: ---
Since 12, at -std=c++17 -O -Wuninitialized:
#include <optional>
struct X {
X() = default;
X(X const& r) : i(r.i) {}
int i;
};
struct Y {
Y() : x() {}
X x;
std::optional<int> o;
};
struct Z {
Y y;
explicit Z(Y y) : y(y) {}
};
void f(Y const&);
void test() {
Y const y;
Z z(y);
z.y.o = 1;
auto const w = z;
f(w.y);
}
In copy constructor 'Y::Y(const Y&)',
inlined from 'void test()' at <source>:19:10:
<source>:7:8: warning: '*(int*)((char*)&y + offsetof(const Y,
Y::o.std::optional<int>::<unnamed>.std::_Optional_base<int, true,
true>::<unnamed>))' is used uninitialized [-Wuninitialized]
7 | struct Y {
| ^
<source>: In function 'void test()':
<source>:18:13: note: 'y' declared here
18 | Y const y;
| ^
Most similar to #80635 and #86465, I think? Although this is -Wuninitialized,
not -Wmaybe-uninitialized.
