[Bug c++/80873] New: ICE in tsubst_copy when trying to use an overloaded function without a definition in a lambda

[hafnermorris at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80873

            Bug ID: 80873
           Summary: ICE in tsubst_copy when trying to use an overloaded
                    function without a definition in a lambda
           Product: gcc
           Version: 7.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hafnermorris at gmail dot com
  Target Milestone: ---

Created attachment 41411
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41411&action=edit
Minimal example code

The following invalid code causes an ICE:

struct S {};

auto overloaded(S &);

template <typename T>
int overloaded(T &) {
    return 0;
}

template <typename T>
auto returns_lambda(T &param) {
        return [&] {
                overloaded(param);
        };
}

int main() {
        S s;
        returns_lambda(s);
}

On Wandbox:
https://wandbox.org/permlink/bU36doHcn0MoXWrK

Only gcc versions 7.1 and up seem to be affected. No compiler flags are
required.