[Bug bootstrap/99983] [9/10 regression] ICE in bootstrap while building libstdc++

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99983

--- Comment #18 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Maxim Kuvyrkov from comment #3)
> It appears to be
> ===
> commit 1c4e8a96cd695c03ff85299bf2392476feae99bb
> Author: François Dumont <fdumont@gcc.gnu.org>
> Date: Mon Jan 20 19:15:43 2020 +0100
> 
> libstdc++: Fix unordered containers move constructors noexcept qualification
> 
> _Hashtable move constructor is wrongly qualified as noexcept(true)
> regardless of
> _Equal and _H1 copy constructor qualifications.
> _Hashtable allocator-aware move constructor is missing its noexcept
> qualification like the depending unordered containers ones.
> 
> This backport also includes the changes from r11-8062.
> ===
> 
> And also confirmed on x86_64, aarch64, and aarch32.

N.B. the original patch on trunk was by François, but the backport was done by
me, with the "changes from r11-8062" which were mine and which caused the
issue. I probably should have kept them separate, so François wouldn't get
blamed.

I didn't see this PR (and that I'd caused it) until I was CC'd in comment 9.
Sorry it took so long to fix.