[Interest] Qt5.11 QDOC Speedup build time and disable PCH?

Google Ersatz googleersatz at oliverniebuhr.de
Fri Dec 14 02:19:21 CET 2018

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Von: Oliver Niebuhr
Gesendet: Freitag, 26. Januar 2018 12:23
An: interest at qt-project.org
Betreff: [Interest] Qt5.11 QDOC Speedup build time and disable PCH?

Hello List.

Those Questions are kind-a target to those who are working with /
Maintaining QDOC [but if someone has an answer: feel free to]:

1.) What were / are the Reason(s) to force the User to Install
LLVM/Clang only for the QDoc Module? Is there a Link to a Discussion

1.)A.) Using LLVM/Clang takes ages to build the Documentation:
* VS 2015, 2017: 8-10 Minutes
* VS 2017 15.5.4 with LLVM 5.0.1: It just reached QtXMLPatterns after 28

This is with a lof of unused Modules not built per Default.

With LLVM, QDoc.exe utilize 26.2 to 29.0 Percent. Any way to speed this
up? Especially as Clang does not Support PCH on Windows.

Which leads to:

2.) I am currently building 5.11 Alpha Snapshot. Problem is (as Clang
does not support PCH's), that with every Single QDocModule, I get this
Error Message:

"libclang: crash detected during AST saving: {
'filename' : 'C:/temp/qdoc_pch.EfXBdO/Qt(Name of Widgets).pch'
'options' : 0,
(qdoc) Could not save PCH file for "Qt(Name of Widget)" 1""

Is there
* A way to disable the use of PCH for QDOC only or
* Are their Ideas / Plans to provide a Setting / Switch etc. for the
final Release, to disable the use of PCH when using QDOC?

Disclaimer: LLVM/Clang Noob and open for Tips and Tricks

Thanks :)

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