https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84516
Bug ID: 84516
Summary: bitfield temporaries > 32-bits have wrong type
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: gnu at mllr dot cc
Target Milestone: ---
(Disclaimer: I'm not a compiler guy, so I may accidentally use the wrong
terminology)
Example: https://godbolt.org/g/brhTMw
#include <iostream>
struct A {
long x : 32;
long y : 33;
};
int main() {
A a;
std::cout << a.x; // OK
std::cout << a.y; // OK
std::cout << +a.x; // OK
std::cout << +a.y; // BREAKS on gcc
}
The problem is the last line. The type of the expression `+a.y` is 'long
int:33', which is not a type that operator<<() has an overload for. The type of
the expression `a.y` is 'long int' and so op<<() has an overload and works.
This issue seems to be affected by
(a) The size of the bit field; <= 32 bits works, > 32 bits breaks.
(b) Whether the bitfield is used in an expression producing a temporary;
>32-bit size AND a temporary breaks, <= 32-bit size and an lvalue works.
I confirmed this behavior on x86-64 gcc trunk using godbolt.org. (link again:
https://godbolt.org/g/brhTMw)
