[Bug c++/92434] noexcept couldn't be deduced in function template

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92434

--- Comment #4 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
That should probably be 
+     if (spec && TREE_PURPOSE (spec) && deducible_expression (TREE_PURPOSE
(spec)))

Note that clang fails if noexcept(B) is changed to e.g. noexcept(!B).