RFA (libstdc++): PATCH to implement C++17 over-aligned new

[Marc Glisse]

On Thu, 8 Sep 2016, Jason Merrill wrote:

> This patch adds support for C++17 allocation of types with alignment
> greater than max_align_t using 'new'.  This is on by default in C++17
> and can also be enabled for other -std= with -falign-new.

Great :-)

> If a user wants to use a different boundary than alignof(max_align_t),
> perhaps because their malloc provides more or less alignment than
> glibc's, they can specify -falign-new=<N>.
>
> The patch also adds a warning about allocating an over-aligned type
> without using an aligned new-operator, which is enabled by -Wall.
>
> libstdc++ folk: Does my configury handling of different C library
> functions that might be usable for aligned allocation make sense?  Is
> the (standard-conforming) implementation of the nothrow allocation
> function OK despite Jonathan's comment in bug 68210?  OK for trunk?

Do we want a generic fallback implementation (similar to 
gcc/config/i386/gmm_malloc.h)? A windows version with _aligned_malloc / 
_aligned_free would also be possible.

-- 
Marc Glisse