[Interest] slower compilation with Qt6

[Cristian Adam]

The compilation time degradation is being tracked at [QTBUG-97601] Compilation speed decrease with Qt 6.2 compared to Qt 5.15.2 - Qt Bug Tracker<https://bugreports.qt.io/browse/QTBUG-97601>

For Qt Creator I use https://ccache.dev/ (yes, it works with MSVC) so that even if it takes longer to compile, I won't be compiling the same file in same situation twice.

Cheers,
Cristian

________________________________
From: Interest <interest-bounces at qt-project.org> on behalf of Hamish Moffatt via Interest <interest at qt-project.org>
Sent: Monday, July 24, 2023 06:11
To: interest at qt-project.org <interest at qt-project.org>
Subject: [Interest] slower compilation with Qt6

I've just finished porting my application from Qt 5.15 to 6.5, and I'm
finding that compilation is significantly slower now - builds take twice
as long or more. For example a linux-g++ build of a project with ~650 .o
files has gone from 45 seconds to 100. I see similar increases on
Windows with MSVC2022, and in other projects with more compilation units.

I'm already using precompiled headers, including a bunch of Qt headers
and some STL.

The next MSVC2022 preview release has a "Build Insights" feature which
shows time spent processing header files, and my biggest culprits are
some headers of mine that use a lot of Q_GADGET and Q_PROPERTY macros.


Does anyone have any suggestions on how to speed things up? I see some
other comments about this online for example
https://forum.qt.io/topic/142309/compilation-times-with-qt6/12



Thanks

Hamish



_______________________________________________
Interest mailing list
Interest at qt-project.org
https://lists.qt-project.org/listinfo/interest
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.qt-project.org/pipermail/interest/attachments/20230724/a7301a3a/attachment.htm>