https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101998
Bug ID: 101998
Summary: false positive: taking address of rvalue
Product: gcc
Version: 11.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: peciva at fit dot vut.cz
Target Milestone: ---
Following code refuses to compile (on g++ 7.5 and 11.2):
struct Nested {
int payload;
};
struct Main {
const Nested* nested;
int payload;
Main(const Nested* n) : nested(n) {}
};
void f(const Main& s)
{
}
int main() {
f(Main(&(const Nested&)Nested())); // <- workaround
f(Main(&Nested())); // <- fails here
return 0;
}
Error message: "error: taking address of rvalue"
I am not c++ expert, but the code seems perfectly meaningful to me. Structure
Main and Nested are both constructed before the call to f and both of them are
destructed after the execution of f. No dangling pointer to destructed
temporary. Both structures (Main, Nested) are temporaries and I do not see a
real reason why the compilation should fail. Maybe, if Main and Nested
instances are both temporaries, the error should not be emitted and compilation
shall proceed (?). But I am not expert.
Such constructions of temporary nested structures and passing pointers to main
structure constructor are often used when programming with c++ Vulkan API, for
instance.
