Can't compile tests

[rbrugo]

If I try to compile tests, GCC gives me this output:

[rbrugo@rbrugo ~/git/lift/build] (master) $ cmake .. && cmake --build .
-- The C compiler identification is GNU 9.2.0
-- The CXX compiler identification is GNU 9.2.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: /home/rbrugo/git/lift/build
Scanning dependencies of target self_test
[ 33%] Building CXX object test/CMakeFiles/self_test.dir/tests.cpp.o
/home/rbrugo/git/lift/test/tests.cpp:40:37: error: non-constant condition for static assertion
   39 | static_assert(lift::when_none(eq<3>,
      |               ~~~~~~~~~~~~~~~~~~~~~~ 
   40 |                               eq<4>)(5),
      |                               ~~~~~~^~~
/home/rbrugo/git/lift/test/tests.cpp:41:40:   in ‘constexpr’ expansion of ‘lift::when_none(Fs&& ...) [with Fs = {const lift::equal(T&&) [with T = int]::<lambda(const auto:3&)>&, const lift::equal(T&&) [with T = int]::<lambda(const auto:3&)>&}](eq<4>)’
/home/rbrugo/git/lift/test/tests.cpp:41:40:   in ‘constexpr’ expansion of ‘lift::negate(F&&) [with F = lift::when_any(Fs&& ...) [with Fs = {const lift::equal(T&&) [with T = int]::<lambda(const auto:3&)>&, const lift::equal(T&&) [with T = int]::<lambda(const auto:3&)>&}]::<lambda(const auto:10& ...)>]()’
/home/rbrugo/git/lift/test/tests.cpp:40:37: error: call to non-‘constexpr’ function ‘lift::when_any(Fs&& ...) [with Fs = {const lift::equal(T&&) [with T = int]::<lambda(const auto:3&)>&, const lift::equal(T&&) [with T = int]::<lambda(const auto:3&)>&}]::<lambda(const auto:10& ...)>::<lambda>(lift::when_any(Fs&& ...) [with Fs = {const lift::equal(T&&) [with T = int]::<lambda(const auto:3&)>&, const lift::equal(T&&) [with T = int]::<lambda(const auto:3&)>&}]::<lambda(const auto:10& ...)>&&)’
In file included from /home/rbrugo/git/lift/test/tests.cpp:14:
/home/rbrugo/git/lift/include/lift.hpp:270:5: note: ‘lift::when_any(Fs&& ...) [with Fs = {const lift::equal(T&&) [with T = int]::<lambda(const auto:3&)>&, const lift::equal(T&&) [with T = int]::<lambda(const auto:3&)>&}]::<lambda(const auto:10& ...)>::<lambda>(lift::when_any(Fs&& ...) [with Fs = {const lift::equal(T&&) [with T = int]::<lambda(const auto:3&)>&, const lift::equal(T&&) [with T = int]::<lambda(const auto:3&)>&}]::<lambda(const auto:10& ...)>&&)’ is not usable as a ‘constexpr’ function because:
  270 |     [funcs = std::tuple(std::forward<Fs>(fs)...)]
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  271 |       (const auto& ... obj)
      |       ~~~~~~~~~~~~~~~~~~~~~
  272 |     noexcept(noexcept((std::forward<Fs>(fs)(obj...) || ...)))
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  273 |   -> bool
      |   ~~~~~~~
  274 |   {
      |   ~  
  275 |     return detail::when_any(
      |     ~~~~~~~~~~~~~~~~~~~~~~~~
  276 |       funcs,
      |       ~~~~~~
  277 |       std::index_sequence_for<Fs...>{},
      |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  278 |       obj...
      |       ~~~~~~
  279 |     );
      |     ~~
  280 |   };
      |   ~  
/home/rbrugo/git/lift/include/lift.hpp:270: confused by earlier errors, bailing out
make[2]: *** [test/CMakeFiles/self_test.dir/build.make:63: test/CMakeFiles/self_test.dir/tests.cpp.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:94: test/CMakeFiles/self_test.dir/all] Error 2
make: *** [Makefile:84: all] Error 2

[rollbear]

OK, it seems like I have yet a compiler bug report to write. gcc-7 handles it, and so does gcc-trunk. Clang 6 and later all handles it.

https://godbolt.org/z/ibXJq8