[Bug target/65146] alignment of _Atomic structure member is not correct

[joseph at codesourcery dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65146

--- Comment #19 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
On Tue, 3 Dec 2019, jason at gcc dot gnu.org wrote:

> Can we please fix this for GCC 10?  It's an important compatibility issue, and
> becoming more important.  Bumping to P1 to raise visibility.

Are we taking "this" to mean specifically the issue described in the bug 
summary, i.e. alignment in structures?  (And not anything about adding 
padding to atomic types, which isn't needed for correctness but might be 
needed on some platforms for ABI compatibility with the system compilers 
but is also likely to need changes somewhere to allow assignments from 
atomic to non-atomic to work properly without e.g. trying to copy the 
padding to a non-atomic type that doesn't include it - that might also 
affect stdatomic.h, which generally uses __atomic_* with temporaries of 
non-atomic type, which thus wouldn't have any such extra padding; maybe 
the generic __atomic_* would need to have special handling of pointers to 
different-sized arguments, or something like that.)