[Bug c++/97419] crash in decl_as_string(TFF_DECL_SPECIFIERS | TFF_CHASE_TYPEDEF) from plugin using std::declval()

[sphink at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97419

--- Comment #7 from Steve Fink <sphink at gmail dot com> ---
I can workaround the bug by avoiding declval:

-   using Iter = decltype(std::declval<const Container>().begin());
-   using Elem = decltype(*std::declval<Iter>());
+   using Iter = decltype(static_cast<const Container*>(nullptr)->begin());
+   using Elem = decltype(*static_cast<const Container*>(nullptr)->begin());

fixes it in my original code. In the minimized testcase, it would be the more
pedestrian

-   using Iter = typename Container::ValueType*;
-   using Elem = decltype(*std::declval<Iter>());
+   using Iter = typename Container::ValueType*;
+   using Elem = typename Container::ValueType;