https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68396
--- Comment #1 from ryan.burn at gmail dot com --- It looks like this was caused with the commit "Handle auto parameter packs." (https://github.com/gcc-mirror/gcc/commit/018c146eec4143116f7f422239d56eb4047be3a4#diff-8570312acacadf34317aa24621800c00) The addition of these lines to the function find_parameter_packs_r in pt.c + if (ppd->type_pack_expansion_p && is_auto_or_concept (t)) + TEMPLATE_TYPE_PARAMETER_PACK (t) = true; are interfering with non-pack autos. If I remove them, the code compiles fine.
