PSA: Chromium build now optionally requires QT

[Thomas Anderson]

Hello Chromium packagers,

As of [1], the build now sets use_qt=true by default.  Of course, it can still be manually set to false in your args.gn.

Additionally, this is only a build-time dependency.  At runtime, Chromium will only use QT if it is available and is running in a QT environment [2].

Finally, the QT feature flag has not yet been toggled (although it will soon), so until then GTK will continue to be used.

[1] https://crrev.com/1044786
[2] https://source.chromium.org/chromium/chromium/src/+/main:ui/linux/linux_ui_factory.cc;drc=849f6a54bd981396d49641a98713576ab1986188;l=133

[Marshall Greenblatt]

Hi Thomas,

Is the plan to completely replace GTK usage with QT? If so, how does this impact Chromium embedders or distributors from a QT licensing perspective?

Thanks,

Marshall

On Sep 22, 2022, at 5:01 PM, Thomas Anderson <thomasa...@chromium.org> wrote:



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[Thomas Anderson]

On Thu, Sep 22, 2022 at 3:04 PM Marshall Greenblatt <magree...@gmail.com> wrote:

Hi Thomas,

Is the plan to completely replace GTK usage with QT?

No, Chromium will choose between GTK and QT at runtime based on the environment.

 

If so, how does this impact Chromium embedders or distributors from a QT licensing perspective?

If you're just distributing a Chromium binary (instead of a whole system that includes QT) then licensing should be unaffected.  Chromium dynamically links against QT, and QT is permissive to dynamic linking.  From QT's website [1]:

In case of dynamic linking, it is possible, but not mandatory, to keep application source code proprietary as long as it is “work that uses the library” – typically achieved via dynamic linking of the library.

I would expect embedders would typically build with both GTK and QT disabled.

[1] https://www.qt.io/licensing/open-source-lgpl-obligations

[Saikrishna Arcot]

Hi Thomas,

Is there a reason that there's no option to generate the moc file used by the Qt build with the moc tool at build time? This makes sure that the moc file that's generated is compatible with the build-time version of Qt.

To view this discussion on the web visit https://groups.google.com/a/chromium.org/d/msgid/chromium-packagers/CAMEXDrnW%3DwBJyxWwQ%3DHtjr7U0LELOsAYyxicrfef1UsH%2BwJJJQ%40mail.gmail.com.

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Saikrishna Arcot

[Thomas Anderson]

There's a related bug for that issue [1].  Can you verify if the patch [2] fixes the issue?

[1] https://bugs.chromium.org/p/chromium/issues/detail?id=1365358

[2] https://chromium.googlesource.com/chromium/src/+/c144231868cea4ec27b92583ee52f6fd87533000