[Bug c++/99845] gcc8: Overloaded operator new[](size_t, const std::nothrow_t&) is seg faulting when the allocation fails

[rguenth at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99845

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2021-03-31
             Status|UNCONFIRMED                 |NEW

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
    allocbuf(uint32_t nelems) {
        return new(std::nothrow) T[static_cast<size_t>(nelems)];
    }

expands to

<<cleanup_point return <retval> = TARGET_EXPR <D.7342, SAVE_EXPR <(sizetype)
nelems> <= 1152921504606846975 ? (size_t) ((SAVE_EXPR <(sizetype) nelems> + 1)
* 8) : (size_t) __cxa_throw_bad_array_new_length ()>;, TARGET_EXPR <D.7341,
MyType::operator new [] (NON_LVALUE_EXPR <D.7342>, (const struct nothrow_t &)
&nothrow)>;;, *(sizetype *) NON_LVALUE_EXPR <D.7341> = SAVE_EXPR <(sizetype)
nelems>;, try
  {
...

which calls MyType::operator new[] and then stores 'nelems' at the beginning
of the allocated storage for some reason (ABI?).

That makes using new[] (std::nothrow) "unsafe" to call it seems?