https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97277
Bug ID: 97277
Summary: Lambda in fold expressions capture arguments are
default initialized
Product: gcc
Version: 7.5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: cusimr at amazon dot com
Target Milestone: ---
https://godbolt.org/z/69ah91
#include <tuple>
#include <iostream>
struct Index {
size_t i;
};
int main() {
std::tuple<int, float, double, size_t> t{1, 2.f, 3, 4};
Index i{1};
std::apply([i](auto&& ...args) {
(..., [i](auto&& arg) { std::cout << arg + i.i << "\n"; }(args));
}, t);
}
g++ -std=c++17
Expected Output:
2, 3, 4, 5
Actual Output:
2, 2, 3, 4
This bit me today and I found this on Ubuntu 18.04 LTS. I realize this is fixed
as of 8.1 but Ubuntu 18.04 LTS is supported until 2023 meaning it's likely this
bug will persist in the wild for at least 3 more years. Not sure if I should
report this as a bug to Ubuntu or if there's a possibility of a backport fix to
7.5 or even a new 7.6 release.
