This warning isn't enabled by default by either -Wall or -Wextra, and
for a good reason. When I do that, it fires also for all uses of
Platform::Application, basically any subclass causes that warning to be
printed as well, even if given subclass is used just once, in an
anonymous namespace, and only through the MAGNUM_APPLICATION_MAIN()
macro. The only solution on Clang is to make such subclasses `final`,
but on GCC not even that helps and one is forced to really make the base
destructor virtual. Which doesn't achieve anything, only adds yet
another entry to the vtable.
So, in the SceneGraph it fixes one particular use case where the warning
was triggered, and since the fix isn't so invasive I'm fine with that.
For Platform I have no idea how an acceptable fix would look like, so I
hope nobody needs any of that anytime soon.
See also https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102168, especially
the part saying "This warning should not be used.".
They're not parsed since 6b22a11170
(2020), so there's no point in keeping those workarounds. They're only
kept in utility application sources as they're parsed for pages, and in
tweakable implementations where it's easier to just copypaste the whole
ifdef expression from the header every time instead of modifying it to
not include DOXYGEN_GENERATING_OUTPUT.
Compared to Corrade, the improvement in compile time is about a minute
cumulative across all cores, or about 8 seconds on an 8-core system (~2
minutes before, ~1:52 after). Not bad at all. And this is with a
deprecated build, the non-deprecated build is 1:48 -> 1:41.
This was due to the internal counter in the object being just 2 bytes,
which was made in order to optimize the Object class size. In practice
however, not counting the vtables, the class has SEVEN pointers and then
a transformation part that's in most cases multiple of 8. Which means
that on 64 bit platforms there was always 5 bytes of padding next to
this 2-byte counter and 1-byte flags, thus no reason to have it 2-byte
anyway.
On 32-bit platforms this *might* cause the Object to get bigger, yes,
but as it's heap-allocated it's more likely that it's put on a
16-byte-aligned address and thus occupying a multiple of 16 bytes
anyway. In any case, this won't really hurt, because the SceneGraph
situation is bad enough already due to all the pointer chasings and
overhead from loose allocations.
Similar to the change done in Corrade, see the commit for details:
878624ac36
Wow, this is probably the most backwards-compatibility code I've ever
written. Can't wait until I can drop all that.
It limits the support for CMake 3.12+, but it's much less verbose and I
don't expect people to use ancient CMake versions with IDEs like Xcode
or VS anyway, so this should be fine.
Before the parent link was gone before destructing the children and that
just didn't make sense. The test added in previous commit now passes as
expected.
This is how it should be but isn't -- the Object inheritance makes it
so first the parent pointer is cleared and only then the children get
destructed. That doesn't really make sense (and I doubt any code relied
on that), so I'll flip it.
Should make new things more discoverable, avoid confusion when a
documented API isn't there and reduce the need for maintaining multiple
separate versions of the docs.
Bloaty says it saved 10 kB in Debug build of MagnumGL:
VM SIZE FILE SIZE
-------------- --------------
[ = ] 0 .debug_info +1.59Ki +0.0%
+0.4% +1.50Ki .text +1.50Ki +0.4%
[ = ] 0 .debug_str +409 +0.0%
[ = ] 0 .debug_line +276 +0.1%
[ = ] 0 .debug_abbrev +20 +0.0%
-28.6% -2 [LOAD [RX]] -2 -28.6%
[ = ] 0 [Unmapped] -4.28Ki -41.0%
-22.7% -9.23Ki .rodata -9.23Ki -22.7%
-0.8% -7.73Ki TOTAL -9.73Ki -0.1%
And 4 kB in Release:
VM SIZE FILE SIZE
-------------- --------------
+1.1% +3.44Ki .text +3.44Ki +1.1%
+1.7% +1.39Ki .eh_frame +1.39Ki +1.7%
[ = ] 0 [Unmapped] +656 +51%
-25.5% -9.47Ki .rodata -9.47Ki -25.5%
-0.7% -4.64Ki TOTAL -4.00Ki -0.4%
That's not negative, so I guess that's good. This change is of course
more significant in the context of a minimal WebGL build, where the exe
can be as little as 50 kB -- there 4 kB is almost 10% of the size.
This makes it possible to:
- finally use Magnum as a CMake subproject on Windows and have your
executables not fail to run with a "DLL missing" error (and the
setting is put to cache so superprojects just implicitly make use of
that)
- run tests on Windows without having to install first
- use dynamic plugins from a CMake subproject on any platform without
having to install first or load them by filename --- and the plugin
directory is now easily discovered as relative to
libraryLocation() of the library implementing given plugin interface
Vladimír Vondruš