https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88419
Casey Carter <Casey at Carter dot net> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords|accepts-invalid | --- Comment #6 from Casey Carter <Casey at Carter dot net> --- Clarifying: The sample TU is valid; It's rejected by GCC 6 because that version does not support C++17 class template argument deduction. I claim that the bug is a regression because 7/8 compile it correctly in default mode, and 9 does not. Yes, it's incorrectly rejected by 7 and 8 as well when compiling with -fchecking=1, so it's *not* a regression that 9 rejects the code with -fchecking=1.