Failed to compile, gcc 7.5.0

[MonkeyDied]

Found errors of the form parameter packs not expanded with ‘...’ and operand of fold expression has no unexpanded parameter packs when compiling things from widget/tuple.hpp. The function causing the error is template <std::size_t... Is> [[nodiscard]] auto indexed_init_children(std::index_sequence<Is...>, typename Widget_t::Parameters... p)

I am using a Ubuntu 18.04 system with gcc 7.5.0.
I checked that, from https://gcc.gnu.org/projects/cxx-status.html#cxx17, the only feature in C++17 not implemented in gcc 7 is P0512R0, something related to Template argument deduction for class templates.

I wonder if this failure is due to the unimplemented feature P0512R0 in gcc 7 ?
If that is the case, is there a workaround to help me out ?

Sampled error messages
[build] /usr/bin/x86_64-linux-gnu-g++-7 -I.../TermOx/include -I.../TermOx/external/signals-light/include -I.../TermOx/external/Escape/include -g -Wall -Wextra -Wpedantic -std=gnu++1z -MD -MT src/CMakeFiles/TermOx.dir/widget/widgets/color_select.cpp.o -MF src/CMakeFiles/TermOx.dir/widget/widgets/color_select.cpp.o.d -o src/CMakeFiles/TermOx.dir/widget/widgets/color_select.cpp.o -c .../TermOx/src/widget/widgets/color_select.cpp
[build] In file included from .../TermOx/include/termox/widget/bordered.hpp:13:0,
[build] from .../TermOx/include/termox/widget/pipe.hpp:18,
[build] from .../TermOx/src/widget/widgets/color_select.cpp:8:
[build] .../TermOx/include/termox/widget/tuple.hpp: In lambda function:
[build] .../TermOx/include/termox/widget/tuple.hpp:83:27: error: parameter packs not expanded with ‘...’:
[build] if constexpr (std::is_constructible_v<
[build] ^~~
[build] .../TermOx/include/termox/widget/tuple.hpp:83:27: note: ‘Widget_t’
[build] .../TermOx/include/termox/widget/tuple.hpp:85:50: error: parameter packs not expanded with ‘...’:
[build] return std::make_unique<Widget_t>(std::move(p));
[build] ~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~
[build] .../TermOx/include/termox/widget/tuple.hpp:85:50: note: ‘__p’
[build] .../TermOx/include/termox/widget/tuple.hpp:85:50: note: ‘Widget_t’
[build] .../TermOx/include/termox/widget/tuple.hpp:87:50: error: parameter packs not expanded with ‘...’:
[build] return std::make_unique<Widget_t>();
[build] ~~~~~~~~~~~~~~~~~~~~~~~~~~^~
[build] .../TermOx/include/termox/widget/tuple.hpp:87:50: note: ‘Widget_t’
[build] .../TermOx/include/termox/widget/tuple.hpp: In member function ‘auto ox::Tuple<Layout_t, Widget_t>::indexed_init_children(std::index_sequence<__indices ...>, typename Widget_t::Parameters ...)’:
[build] .../TermOx/include/termox/widget/tuple.hpp:89:10: error: operand of fold expression has no unexpanded parameter packs
[build] ...);
[build] ^~~