[Bug c++/65945] C++ alignment of nullptr_t is 1 and might cause unaligned stores to the frame

[foom at fuhm dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65945

James Y Knight <foom at fuhm dot net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |foom at fuhm dot net

--- Comment #9 from James Y Knight <foom at fuhm dot net> ---
This also happens on Sparc. A test-case is really easy to make:

int foo(bool&&, decltype(nullptr)&&, bool&&);

void doit() {
  foo(false, nullptr, false);
}


        save    %sp, -104, %sp
        stb     %g0, [%fp-6]
  /* WTF unaligned store */
        st      %g0, [%fp-5]
        stb     %g0, [%fp-1]
        add     %fp, -6, %g3
        add     %fp, -5, %g2
        add     %fp, -1, %g1
        mov     %g3, %o0
        mov     %g2, %o1
        mov     %g1, %o2
        call    _Z3fooObODnS_, 0
         nop
        return  %i7+8
         nop

        .ident  "GCC: (Debian 4.9.2-10) 4.9.2"


This breaks building recent versions of clang on Sparc, because it calls
emplace_back with nullptr, which results in an expression like the above.