<algorithm>: ranges::is_permutation's helper lambda does not specify return type #2888
Description
Lines 1010 to 1013 in ef62d3f
Lines 1099 to 1102 in ef62d3f
The lambda needs to specify return type eg -> bool since boolean-testable only requires that the return type of Pred can be converted to bool.
#include <algorithm>
struct Bool {
operator bool() { return true; };
Bool() = default;
Bool(const Bool&) = delete;
};
int main() {
Bool b;
int x[] = {42};
std::ranges::is_permutation(x, x, [&](auto, auto) -> Bool& { return b; });
}