https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94058
Bug ID: 94058
Summary: defaulted three way comparison operator defined as
deleted when a member is a small bitfield of long
type.
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: okannen at gmail dot com
Target Milestone: ---
Version: GCC 10.0.1 20200229
Exemple of code:
#include <compare>
struct A{
long i : 48;
auto operator <=> (const A&) const = default;
};
struct B{
long i : 8;
auto operator <=> (const B&) const = default;
};
void f(A a, B b){
a <=> a; //OK
b <=> b; //error (see bellow)
}
Error message:
<source>: In function 'void f(A, B)':
<source>:15:11: error: use of deleted function 'constexpr auto
B::operator<=>(const B&) const'
15 | b <=> b;
| ^
<source>:10:10: note: 'constexpr auto B::operator<=>(const B&) const' is
implicitly deleted because the default definition would be ill-formed:
10 | auto operator <=> (const B&) const = default;
| ^~~~~~~~
<source>:10:10: warning: narrowing conversion of '((const B*)this)->B::i' from
'long int' to 'int' [-Wnarrowing]
<source>:10:10: warning: narrowing conversion of '<anonymous>.B::i' from 'long
int' to 'int' [-Wnarrowing]
Compiler returned: 1
