* speeds up incremental builds as changes to a header will not always
need the full mocs_compilation.cpp for all the target's headers rebuild,
while having a moc file sourced into a source file only adds minor
extra costs, due to small own code and the used headers usually
already covered by the source file, being for the same class/struct
* seems to not slow down clean builds, due to empty mocs_compilation.cpp
resulting in those quickly processed, while the minor extra cost of the
sourced moc files does not outweigh that in summary.
Measured times actually improved by some percent points.
(ideally CMake would just skip empty mocs_compilation.cpp & its object
file one day)
* enables compiler to see all methods of a class in same compilation unit
to do some sanity checks
* potentially more inlining in general, due to more in the compilation unit
* allows to keep using more forward declarations in the header, as with the
moc code being sourced into the cpp file there definitions can be ensured
and often are already for the needs of the normal class methods
Due to being a compositor, kwin has to conform to some certain
interfaces. It means a lot of virtual functions and function tables to
integrate with C APIs. Naturally, we not always want to use every
argument in such functions.
Since we get -Wunused-parameter from -Wall, we have to plumb those
unused arguments in order to suppress compiler warnings at the moment.
However, I don't think that extra work is worth it. We cannot change or
alter prototypes in any way to fix the warning the desired way. Q_UNUSED
and similar macros are not good indicators of whether an argument is
used too, we tend to overlook putting or removing those macros. I've
also noticed that Q_UNUSED are not used to guide us with the removal no
longer needed parameters.
Therefore, I think it's worth adding -Wno-unused-parameter compiler
option to stop the compiler producing warnings about unused parameters.
It changes nothing except that we don't need to put Q_UNUSED anymore,
which can be really cumbersome sometimes. Note that it doesn't affect
unused variables, you'll still get a -Wunused-variable compiler warning
if a variable is unused.
Summary:
Remove unused variables and members.
We were often storing the q of classes without ever needing them. I'd
just do it when it's useful. We do it in the private class so it can
always be added, removes boilerplate code.
Don't use std::move when returning temporary QImage. The compiler is
smart enough to know to do it but produces the warning "moving a
temporary object prevents copy elision".
Remove unused lambda captured variables.
Test Plan: Getting much cleaner build logs
Reviewers: #frameworks, #kwin, zzag
Reviewed By: #kwin, zzag
Subscribers: zzag, kde-frameworks-devel
Tags: #frameworks
Differential Revision: https://phabricator.kde.org/D28442
Vlad Zahorodnii
Laurent Montel
Alexander Lohnau
Aleix Pol
Andreas Cord-Landwehr
Martin Gräßlin