https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87145
Bug ID: 87145
Summary: Implicit conversion to scoped enum fails: "error:
taking address of temporary/rvalue"
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: programmer at posteo dot de
Target Milestone: ---
The following code can be compiled with GCC 6.3, but GCC 7.1 and later abort
the compilation with an error message.
=====
#include <cstddef>
#include <type_traits>
enum class Enum : std::size_t {};
struct Pod {
std::size_t val;
constexpr operator Enum() const {
return static_cast<Enum>(val);
}
};
template<std::size_t N>
constexpr void foo() {
using Foo = std::integral_constant<Enum, Pod{N}>;
}
int main() {
foo<2>();
}
=====
Error message from current trunk:
=====
<source>: In instantiation of 'constexpr void foo() [with long unsigned int N =
2]':
<source>:21:10: required from here
<source>:17:50: error: taking address of rvalue [-fpermissive]
17 | using Foo = std::integral_constant<Enum, Pod{N}>;
| ^
<source>:17:50: error: no matching function for call to 'Pod::operator
Enum(Pod*)'
<source>:10:13: note: candidate: 'constexpr Pod::operator Enum() const'
10 | constexpr operator Enum() const {
| ^~~~~~~~
<source>:10:13: note: candidate expects 0 arguments, 1 provided
Compiler returned: 1
=====
Live demo: https://godbolt.org/z/vfvGiS
PS: Which version should I choose if multiple versions are affected: stable,
trunk or [the first version with that regression]?
