Build fails on i386

[mr-c]

Platform

• SeqAn version: 3.0.0
• Operating system: Linux 4.19.0-6-amd64 [INTERNAL] Renamed sequence file headers. #1 SMP Debian 4.19.67-2+deb10u2 (2019-11-11) amd64 (x86_64)
• Compiler: 9.2.1

Description

How to repeat the problem

Build the seqan3 debian package on an i386 system

Expected behaviour

Build complete

Actual behaviour

/include/seqan3/alphabet/concept.hpp:155:22: error: invalid parameter type ‘seqan3::alphabet_rank_t<wchar_t&>’ {aka ‘void’}
/include/seqan3/alphabet/concept.hpp:155:22: error: in declaration ‘constexpr alph_t seqan3::detail::adl::only::assign_rank_to_fn::operator()(seqan3::alphabet_rank_t<alph_t>, alph_t&&) const’
In file included from /usr/include/gtest/gtest.h:375,
                 from test/unit/alphabet/adaptation/char_test.cpp:10:
test/unit/alphabet/adaptation/char_test.cpp:80:5: error: invalid use of void expression
   80 |     EXPECT_EQ(to_rank(TypeParam{65}), cmp);
      |     ^
test/unit/alphabet/adaptation/char_test.cpp:70:15: error: invalid application of ‘sizeof’ to a void type [-Werror=pointer-arith]
   70 |     EXPECT_GE(sizeof(alphabet_rank_t<TypeParam>), sizeof(TypeParam));
      |               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Full log: https://buildd.debian.org/status/fetch.php?pkg=seqan3&arch=i386&ver=3.0.0%2Bds2-2&stamp=1574012481&raw=0

[mr-c]

From @marehr "we don't support 32 bit systems [yet]"

#1481 has been opened to document this