[Clang] No diagnostic for attribute in front of extern declarations (original) (raw)

Clang currently accepts

template struct Test {};

[[deprecated]] extern template struct Test;

but doesn't diagnose the use of Test<int>. I've also tried other attributes and Clang seems to accepts everyhing, even attributes like [[fallthrough]]. I'm pretty sure it's actually invalid code that Clang accepts silently. GCC and MSVC reject the code with not super great diagnostics.