title: FreeFileSync C++ error: 'byte' is not a member of 'std'
body: <p>I'm trying to build open source program and getting this error:</p>
  
  <pre><code>$ make
  mkdir -p ../Obj/FFS_GCC_Make_Release/ffs/src/base/
  g++ -std=c++17 -pipe -DWXINTL_NO_GETTEXT_MACRO -I../.. -I../../zenXml -include "zen/i18n.h" -include "zen/warn_static.h" -Wall -Wfatal-errors -Wmissing-include-dirs -Wswitch-enum -Wcast-align -Wshadow -Wnon-virtual-dtor -O3 -DNDEBUG `wx-config --cxxflags --debug=no` -pthread `pkg-config --cflags gtk+-2.0` -c base/algorithm.cpp -o ../Obj/FFS_GCC_Make_Release/ffs/src/base/algorithm.o
  In file included from base/../fs/abstract.h:13:0,
                   from base/structures.h:14,
                   from base/file_hierarchy.h:20,
                   from base/algorithm.h:11,
                   from base/algorithm.cpp:7:
  ../../zen/serialize.h:35:45: error: ‘byte’ is not a member of ‘std’
       using value_type     = std::vector&lt;std::byte&gt;::value_type;
                                               ^~~~
  compilation terminated due to -Wfatal-errors.
  Makefile:108: recipe for target '../Obj/FFS_GCC_Make_Release/ffs/src/base/algorithm.o' failed
  make: *** [../Obj/FFS_GCC_Make_Release/ffs/src/base/algorithm.o] Error 1
  </code></pre>
  
  <p>This source file contains <code>#include &lt;cstdint&gt;</code></p>
  
  <p>Here is a problem part of code: 
  <code>using value_type = std::vector&lt;std::byte&gt;::value_type;
  </code></p>
  
  <p>How to reproduce: Download FreeFileSync source from official website, unpack</p>
  
  <pre><code>cd FreeFileSync_10.4_Source\FreeFileSync\Source
  make
  </code></pre>
  
  <p>gcc version 7.3.0 (Ubuntu 7.3.0-27ubuntu1~18.04) under Windows Subsystem for Linux</p>