[Bug c++/85118] [6/7/8 Regression] Error when using std::bind with a generic lambda - "cannot bind 'const volatile char&' to an rvalue of type 'const volatile char'"

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85118

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Started to be rejected with r233719

            PR c++/69842
            * method.c (forward_parm): Handle parameter packs.
            * lambda.c (maybe_add_lambda_conv_op): Use it for them.

Still reducing it.