[itzTheMeow]

nixpkgs upgraded their gcc toolchain to GCC 16 which sets the default C++ dialect to C++20 which causes some build failures that i encountered while packaging
source: https://gcc.gnu.org/gcc-16/changes.html#cxx

we can get around this with the build flag -DCMAKE_CXX_STANDARD=17, however given that the 2017 C++ standard is almost 10 years old it's possible that it gets deprecated in the future

this pr fixes those explicit failures. theres still some deprecation warnings when building this with the newer toolchain, however the application still builds and functions

i tested both builds under gcc15 and gcc16 and they appear to work normally and all tests pass

[mmatyas]

An established, registered industry standard doesn't just "get deprecated", and even C++98 is perfectly supported, but I agree it's beneficial to keep things up to date. Could you also post the errors you encounter? The reinterpret part is understandable, but from the top of my head, I don't remember what new rule causes Entry and Error to need an explicit constructor.

[itzTheMeow]

The initializer lists gave me this error:

/build/source/src/backend/parsers/MetaFile.cpp:140:16: error: no match for call to '(const std::function<void(const metafile::Error&)>) (<brace-enclosed initializer list>)'
  140 |         onError({ linenum, LOGMSG("line invalid, skipped") });
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  • there is 1 candidate
    /nix/store/5q6bdxkp7lc70gn9mnf4yiybrx8ry5xq-gcc-16.2.0/include/c++/16.2.0/bits/std_function.h:324:11:
      324 |     class function<_Res(_ArgTypes...)>
          |           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
    • candidate 1: '_Res std::function<_Res(_ArgTypes ...)>::operator()(_ArgTypes ...) const [with _Res = void; _ArgTypes = {const metafile::Error&}]'
      /nix/store/5q6bdxkp7lc70gn9mnf4yiybrx8ry5xq-gcc-16.2.0/include/c++/16.2.0/bits/std_function.h:577:7:
        577 |       operator()(_ArgTypes... __args) const
            |       ^~~~~~~~
      • no known conversion for argument 1 from '<brace-enclosed initializer list>' to 'const metafile::Error&'
        /nix/store/5q6bdxkp7lc70gn9mnf4yiybrx8ry5xq-gcc-16.2.0/include/c++/16.2.0/bits/std_function.h:577:27:
          577 |       operator()(_ArgTypes... __args) const
              |                  ~~~~~~~~~^~~~~~~~~~
make[2]: *** [src/backend/CMakeFiles/pegasus-backend.dir/build.make:226: src/backend/CMakeFiles/pegasus-backend.dir/parsers/MetaFile.cpp.o] Error 1

[mmatyas]

Wouldn't specifying the type fix this? onError(Error { linenum, LOGMSG("line invalid, skipped") });

[itzTheMeow]

made this change and got the full error

/home/xela/Documents/pegasus-frontend/src/backend/parsers/MetaFile.cpp: In function ‘void metafile::read_stream(QTextStream&, const std::function<void(const Entry&)>&, const std::function<void(const Error&)>&)’:
/home/xela/Documents/pegasus-frontend/src/backend/parsers/MetaFile.cpp:73:23: error: no matching function for call to ‘metafile::Error::Error(<brace-enclosed initializer list>)’
   73 |     Error error {0, {}};
      |                       ^
  • there is 1 candidate
In file included from /home/xela/Documents/pegasus-frontend/src/backend/parsers/MetaFile.h:20,
                 from /home/xela/Documents/pegasus-frontend/src/backend/parsers/MetaFile.cpp:18:
    • candidate 1: ‘metafile::Error::Error(metafile::Error&&)’
      /home/xela/Documents/pegasus-frontend/src/backend/parsers/MetaFile.h:44:15:
         44 |     MOVE_ONLY(Error)
            |               ^~~~~
    • in definition of macro ‘MOVE_ONLY’
         23 |     T(T&&) = default; \
            |     ^
      • candidate expects 1 argument, 2 provided
      • in definition of macro ‘MOVE_ONLY’
           23 |     T(T&&) = default; \
              |     ^
/home/xela/Documents/pegasus-frontend/src/backend/parsers/MetaFile.cpp:74:27: error: no matching function for call to ‘metafile::Entry::Entry(<brace-enclosed initializer list>)’
   74 |     Entry entry {0, {}, {}};
      |                           ^
  • there is 1 candidate
    • candidate 1: ‘metafile::Entry::Entry(metafile::Entry&&)’
      /home/xela/Documents/pegasus-frontend/src/backend/parsers/MetaFile.h:38:15:
         38 |     MOVE_ONLY(Entry)
            |               ^~~~~
    • in definition of macro ‘MOVE_ONLY’
         23 |     T(T&&) = default; \
            |     ^
      • candidate expects 1 argument, 3 provided
      • in definition of macro ‘MOVE_ONLY’
           23 |     T(T&&) = default; \
              |     ^
/home/xela/Documents/pegasus-frontend/src/backend/parsers/MetaFile.cpp: In lambda function:
/home/xela/Documents/pegasus-frontend/src/backend/parsers/MetaFile.cpp:79:94: error: no matching function for call to ‘metafile::Error::Error(<brace-enclosed initializer list>)’
   79 |                 onError(Error { entry.line, LOGMSG("attribute value missing, entry ignored") });
      |                                                                                              ^
  • there is 1 candidate
    • candidate 1: ‘metafile::Error::Error(metafile::Error&&)’
      /home/xela/Documents/pegasus-frontend/src/backend/parsers/MetaFile.h:44:15:
         44 |     MOVE_ONLY(Error)
            |               ^~~~~
    • in definition of macro ‘MOVE_ONLY’
         23 |     T(T&&) = default; \
            |     ^
      • candidate expects 1 argument, 2 provided
      • in definition of macro ‘MOVE_ONLY’
           23 |     T(T&&) = default; \
              |     ^
/home/xela/Documents/pegasus-frontend/src/backend/parsers/MetaFile.cpp: In function ‘void metafile::read_stream(QTextStream&, const std::function<void(const Entry&)>&, const std::function<void(const Error&)>&)’:
/home/xela/Documents/pegasus-frontend/src/backend/parsers/MetaFile.cpp:105:119: error: no matching function for call to ‘metafile::Error::Error(<brace-enclosed initializer list>)’
  105 |                 onError(Error { linenum, LOGMSG("line starts with whitespace, but no attribute has been defined yet") });
      |                                                                                                                       ^
  • there is 1 candidate
    • candidate 1: ‘metafile::Error::Error(metafile::Error&&)’
      /home/xela/Documents/pegasus-frontend/src/backend/parsers/MetaFile.h:44:15:
         44 |     MOVE_ONLY(Error)
            |               ^~~~~
    • in definition of macro ‘MOVE_ONLY’
         23 |     T(T&&) = default; \
            |     ^
      • candidate expects 1 argument, 2 provided
      • in definition of macro ‘MOVE_ONLY’
           23 |     T(T&&) = default; \
              |     ^
/home/xela/Documents/pegasus-frontend/src/backend/parsers/MetaFile.cpp:140:66: error: no matching function for call to ‘metafile::Error::Error(<brace-enclosed initializer list>)’
  140 |         onError(Error { linenum, LOGMSG("line invalid, skipped") });
      |                                                                  ^
  • there is 1 candidate
    • candidate 1: ‘metafile::Error::Error(metafile::Error&&)’
      /home/xela/Documents/pegasus-frontend/src/backend/parsers/MetaFile.h:44:15:
         44 |     MOVE_ONLY(Error)
            |               ^~~~~
    • in definition of macro ‘MOVE_ONLY’
         23 |     T(T&&) = default; \
            |     ^
      • candidate expects 1 argument, 2 provided
      • in definition of macro ‘MOVE_ONLY’
           23 |     T(T&&) = default; \
              |     ^

aforementioned macro:

[mmatyas]

Eh whatever, let's just roll with it. Thanks again!