`std::size_t` is used without including any standard library header

[Kojoley]

Typeof seems to be relying on Config to include <cstddef> but it is no longer a case in C++20/VS2019.

https://www.boost.org/development/tests/develop/developer/output/teeks99-07-v16d-64onAMD64-boost-bin-v2-libs-typeof-test-data_member_emulation-test-msvc-14-2-dbg-adrs-mdl-64-thrd-mlt.html

.\boost/typeof/typeof_impl.hpp(88): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/int_encoding.hpp(40): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/int_encoding.hpp(46): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/int_encoding.hpp(55): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/int_encoding.hpp(62): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/int_encoding.hpp(79): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/int_encoding.hpp(82): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/int_encoding.hpp(89): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/modifiers.hpp(53): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/modifiers.hpp(54): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/modifiers.hpp(55): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/modifiers.hpp(56): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/modifiers.hpp(57): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/modifiers.hpp(113): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/modifiers.hpp(114): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/modifiers.hpp(115): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/modifiers.hpp(116): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/pointers_data_members.hpp(24): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(26): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(35): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(62): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(71): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(96): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(105): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(26): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(35): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(62): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(71): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(96): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(105): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(26): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(35): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(62): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(71): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(96): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(105): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(26): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(35): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(62): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(71): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(96): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(105): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(26): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(35): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(62): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(71): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(96): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(105): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(26): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(35): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(62): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(71): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(96): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(105): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(26): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(35): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(62): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(71): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(96): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(105): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(26): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(35): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(62): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(71): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(96): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(105): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_mem_functions.hpp(18): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(26): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(35): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(62): error C2039: 'size_t': is not a member of 'std'
predefined C++ types (compiler internal)(368): note: see declaration of 'std'
.\boost/typeof/register_functions_iterate.hpp(62): fatal error C1003: error count exceeds 100; stopping compilation
    call "bin.v2\standalone\msvc\msvc-14.2\address-model-64\architecture-x86\msvc-setup.bat"  >nul