https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103951
Bug ID: 103951
Summary: [C++2b] string_view range constructor, "exception
specification ... depends on itself"
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: iamsupermouse at mail dot ru
Target Milestone: ---
Following code compiles with -std=c++20 and earlier, but fails with -std=c++2b,
in both GCC and Clang with libstdc++, with similar errors.
I've tested both on GCC 11.2 and on trunk 12.0.0 20220109 at gcc.godbolt.org.
#include <string_view>
struct Iter
{
Iter() {}
Iter(std::string_view) {} // Adding `explicit` fixes the error
Iter begin() const
{
return *this;
}
};
It's supposed to be used as `for (auto x : Iter(...))`, exactly like
`fs::directory_iterator`, but I've removed `end()` and overloaded operators for
brevity.
The error message boils down to `return *this` considering the `string_view`
constructor, which checks `Iter` against `contiguous_range`, which circularly
checks `begin()`.
I'm not sure if the code is legal or not, but the error is very unintuitive, so
I decided to report it. I would expect this to be a soft SFINAE failure.
