https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104326
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Hmm, only clang is able to accept the code.
MSVC rejects it with:
<source>(13): error C3520: 'Types': parameter pack must be expanded in this
context
While ICC ICEs after an error message:
<source>(10): error: parameter pack "Types" was referenced but not expanded
template <Types> typename... Outer,
^
<source>(11): error: parameter pack "Types" was referenced but not expanded
Types... Inner
^
<source>(19): internal error: null pointer
Test<tuple<O1<1>, O2<2>>> test1;
^
