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

[Marc Glisse]

On Sat, 10 Sep 2016, Christophe Lyon wrote:

> On aarch64*-elf and arm-eabi (using newlib), I'm seeing:
> /gccsrc/libstdc++-v3/libsupc++/new_opa.cc:66: undefined reference to
> `aligned_alloc'

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;a=commit;h=f86afe5a3ac62a92e821c764a011e1625abdd326

"C11 aligned_alloc() implementation

aligned_alloc() is implemented in terms of posix_memalign() which is
only declared in <stdlib.h> but not defined in Newlib in general.  At
least Linux and RTEMS implement this function."

If we don't want to provide a fallback implementation in libsupc++, we can 
say that aligned new is unsupported on those platforms, but if we are 
building a shared libstdc++.so that doesn't like undefined symbols, we 
need a different failure mode than an undefined aligned_alloc. Either not 
providing operator new(...aligned_val_t...) in libstdc++ or providing one 
that just aborts I guess?

-- 
Marc Glisse