Add support cmake unity build

[tnixeu]

This PR prepares building with CMAKE_UNITY_BUILD enabled. This makes builds often a bit faster and the executables often a bit smaller.

I tried to keep the changes as small as possible and without renaming variables. This is why I exclude the file causing troubles from the unity build or added macros in order to avoid defining a variable multiple times.

I timed the builds with time ninja

Unity build: nextcloud 5.6M

real    0m42,137s
user    3m36,684s
sys     0m17,226s

Normal build: nextcloud 5.8M

real    0m46,048s
user    9m13,199s
sys     0m45,951s

[tnixeu]

I logged in with this version, synced a view files. It seems fine by me.

None of my changes should currently have an impact at runtime, because the Appimage is probably not yet built with CMAKE_UNITY_BUILD turned on.

[mgallien]

thanks a lot that is nice
would you like to also try activating it for the AppImage ?
I can help and guide you if you want

[mgallien]

please can you replace them by the following code

namespace {
constexpr auto versionC= "version";
}

can you also apply the same solution to the few other occurrences

[mgallien]

please ignore that comment
it is indeed not compiling
so please use

namespace {
#ifndef VERSION_C
#define VERSION_C
constexpr auto versionC= "version";
#endif
}

[mgallien]

I am also getting a build failure if the dolphin native plugin is getting build due to a conflict between signals macro from Qt headers and some code in this header /usr/include/glib-2.0/gio/gdbusintrospection.h
maybe you could also add this file src/3rdparty/kmessagewidget/kmessagewidget.cpp to the list of files not included in unity builds ?

To solve the build failures I added the following lines src/gui/CMakeLists.txt

set_property(SOURCE ../3rdparty/kmessagewidget/kmessagewidget.cpp PROPERTY SKIP_UNITY_BUILD_INCLUSION ON)
set_property(SOURCE ../3rdparty/kirigami/wheelhandler.cpp PROPERTY SKIP_UNITY_BUILD_INCLUSION ON)

[mgallien]

I logged in with this version, synced a view files. It seems fine by me.

None of my changes should currently have an impact at runtime, because the Appimage is probably not yet built with CMAKE_UNITY_BUILD turned on.

You would need to add the extra configure option in this file https://github.com/nextcloud/desktop/blob/master/admin/linux/build-appimage.sh

[codecov]

Codecov Report

Merging #5109 (5eadb26) into master (0fe476e) will increase coverage by 0.01%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5109      +/-   ##
==========================================
+ Coverage   57.56%   57.58%   +0.01%     
==========================================
  Files         138      138              
  Lines       17399    17399              
==========================================
+ Hits        10016    10019       +3     
+ Misses       7383     7380       -3     

Impacted Files	Coverage Δ
src/libsync/discovery.cpp	88.33% <0.00%> (+0.30%)	⬆️

[mgallien]

thanks

[nextcloud-desktop-bot]

AppImage file: nextcloud-PR-5109-5eadb269a614567ce5f7b5ac0e2b97387ec9c25b-x86_64.AppImage

To test this change/fix you can simply download above AppImage file and test it.

Please make sure to quit your existing Nextcloud app and backup your data.