https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88555
Bug ID: 88555 Summary: [9 Regression] Pack expansion fails Product: gcc Version: 9.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: eric at efcs dot ca Target Milestone: --- GCC fails to expand parameter packs when used in certain contexts. This is a regression from 8.2. https://godbolt.org/z/9MrTQQ Reproducer: // g++ -std=c++17 template <class ...> struct T {}; template <int ...Indices> void test() { using Test = T<decltype((Indices, char(0)))...>; }