Build Fails on Fedora 34 with gcc-11.2.1-1.fc34.x86_64

When I try to build either -head or the current release, I first get this warning-forced-to-error:

src/download_manager.cpp:131:80: error: loop variable ‘p’ of type ‘const std::pair<unsigned int, browservice::DownloadManager::DownloadInfo>&’ binds to a temporary constructed from type ‘std::pair<const unsigned int, browservice::DownloadManager::DownloadInfo>’ [-Werror=range-loop-construct]
  131 | pair<uint32_t, browservice::DownloadManager::DownloadInfo>& p : infos_) {
      |                                                             ^

src/download_manager.cpp:131:80: note: use non-reference type ‘const std::pair<unsigned int, browservice::DownloadManager::DownloadInfo>’ to make the copy explicit or ‘const std::pair<const unsigned int, browservice::DownloadManager::DownloadInfo>&’ to prevent copying
src/download_manager.cpp: In member function ‘void browservice::DownloadManager::downloadProgressChanged_()’:
src/download_manager.cpp:201:80: error: loop variable ‘elem’ of type ‘const std::pair<unsigned int, browservice::DownloadManager::DownloadInfo>&’ binds to a temporary constructed from type ‘std::pair<const unsigned int, browservice::DownloadManager::DownloadInfo>’ [-Werror=range-loop-construct]
  201 | pair<uint32_t, browservice::DownloadManager::DownloadInfo>& elem : infos_) {
      |                                                             ^~~~

I can work around this by adding "-Wno-error=range-loop-construct" to CFLAGS_COMMON. However, this just gets me to a different set of errors:

In file included from /usr/include/c++/11/bits/move.h:57,
                 from /usr/include/c++/11/bits/stl_pair.h:59,
                 from /usr/include/c++/11/bits/stl_algobase.h:64,
                 from /usr/include/c++/11/memory:63,
                 from src/png.hpp:28,
                 from src/png.cpp:25:
/usr/include/c++/11/type_traits: In instantiation of ‘struct std::is_destructible<{anonymous}::Result>’:
/usr/include/c++/11/future:1065:21:   required from ‘class std::promise<{anonymous}::Result>’
src/png.cpp:133:26:   required from here
/usr/include/c++/11/type_traits:849:52: error: static assertion failed: template argument must be a complete class or an unbounded array
  849 |       static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
      |                     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

There are a bunch of other "error: static assertion failed: template argument must be a complete class or an unbounded array" errors in png.cpp.

ttalvitie / browservice

Build Fails on Fedora 34 with gcc-11.2.1-1.fc34.x86_64 #52