https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122313
--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Here's a C++17 test that doesn't rely on parenthesized init of aggregates:
#include <vector>
#include <memory_resource>
void test1()
{
#if __cplusplus >= 202002L
struct S { int i; };
static_assert(std::is_constructible_v<S, int&>);
std::vector<int> base_v;
std::vector<S> v;
v.insert(v.end(), base_v.begin(), base_v.end());
#endif
}
void test2()
{
struct S { explicit S(int) { } };
static_assert(std::is_constructible_v<S, int&>);
std::vector<int> base_v;
std::vector<S> v;
v.insert(v.end(), base_v.begin(), base_v.end());
}
void test3()
{
struct S {
S(int) { }
void operator=(int) = delete;
};
static_assert(std::is_constructible_v<S, int&>);
std::vector<int> base_v;
std::vector<S> v;
v.insert(v.end(), base_v.begin(), base_v.end());
}
void test4()
{
struct S {
using allocator_type = std::pmr::polymorphic_allocator<S>;
S() { }
S(allocator_type) { }
S(int) { throw; }
S(int, allocator_type) { }
S(const S&, allocator_type) { }
};
static_assert(std::is_constructible_v<S, int&>);
std::vector<int> base_v(1);
std::pmr::vector<S> v(1);
v.reserve(2);
v.insert(v.begin(), base_v.begin(), base_v.end());
}
int main()
{
test1();
test2();
test3();
test4();
}
test1 is ill-formed in C++20 (and a no-op in C++17), test2, and test3 are
ill-formed in all cases, and test4 fails at runtime.
They should all compile and run successfully.
