FAILED: src/libutil/libnixutil.dll.p/windows_environment-variables.cc.obj 
  "clang++" "-Isrc/libutil/libnixutil.dll.p" "-Isrc/libutil" "-I../nix-2.25.0/src/libutil" "-Isrc/libutil/windows" "-I../nix-2.25.0/src/libutil/windows" "-fdiagnostics-color=always" "-D_LIBCPP_HARDENING_MODE=_LIBCPP_HARDENING_MODE_FAST" "-D_FILE_OFFSET_BITS=64" "-Wall" "-Winvalid-pch" "-std=c++2a" "-include" "config-util.hh" "-Wdeprecated-copy" "-Werror=suggest-override" "-Werror=switch" "-Werror=switch-enum" "-Werror=unused-result" "-Wignored-qualifiers" "-Wimplicit-fallthrough" "-Wno-deprecated-declarations" "-D_WIN32_WINNT=0x0602" "-march=nocona" "-msahf" "-mtune=generic" "-O2" "-pipe" "-Wp,-D_FORTIFY_SOURCE=2" "-fstack-protector-strong" "-Wp,-D__USE_MINGW_ANSI_STDIO=1" "-DBOOST_CONTEXT_DYN_LINK=1" "-DBOOST_COROUTINES_DYN_LINK=1" "-DBOOST_ALL_NO_LIB" "-pthread" -MD -MQ src/libutil/libnixutil.dll.p/windows_environment-variables.cc.obj -MF "src/libutil/libnixutil.dll.p/windows_environment-variables.cc.obj.d" -o src/libutil/libnixutil.dll.p/windows_environment-variables.cc.obj "-c" ../nix-2.25.0/src/libutil/windows/environment-variables.cc
  ../nix-2.25.0/src/libutil/windows/environment-variables.cc:16:31: error: non-constant-expression cannot be narrowed from type 'DWORD' (aka 'unsigned long') to 'wchar_t' in initializer list [-Wc++11-narrowing]
     16 |     std::wstring value{L'\0', bufferSize};
        |                               ^~~~~~~~~~
  ../nix-2.25.0/src/libutil/windows/environment-variables.cc:16:31: note: insert an explicit cast to silence this issue
  
     16 |     std::wstring value{L'\0', bufferSize};
  
        |                               ^~~~~~~~~~
  
        |                               static_cast<wchar_t>( )
  
  1 error generated.