https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116909
--- Comment #6 from Federico Kircheis <federico at kircheis dot it> ---
Thank, I think this covers all my concern.
Nevertheless I was still looking how to avoid the assembly, eventually to be
sure to have a more portable piece of code (with less ifdefs) between compilers
auto get_tests() noexcept {
extern const test_signature* const tests_begin[];
extern const test_signature* const tests_end[];
const auto tests_size = ((uintptr_t)(&tests_end) -
(uintptr_t)(&tests_begin))/sizeof(test_signature*);
auto begin = std::start_lifetime_as_array<test_signature* const>(tests_begin,
tests_size);
return std::span<test_signature* const>(begin, begin + tests_size);
}
With the cast to uintptr_t, I can get the size of the non-existent array
without UB.
With std::start_lifetime_as_array, I can tell the compiler there is an array.
I believe with this construct, the assembly should not be necessary anymore
(although a more modern compiler is required, as start_lifetime_as_array comes
with c++23, and there seem to be no equivalent for C).
