depends: Do not force Precompiled Headers (PCH) for building Qt on Linux #20520

pull hebasto wants to merge 1 commits into bitcoin:master from hebasto:201127-pch changing 2 files +4 −3

hebasto commented at 6:00 PM on November 27, 2020: member

On CentOS 8 (Cirrus CI job) the forced -pch option breaks Qt build.

Removing -pch option does not affect build time for other systems:

master (e2ff5e7b35d71195278d2a2ed9485f141de33d7a):

$ time make -j 9 -C depends/ qt
...
Caching qt...
make: Leaving directory '/home/hebasto/guix/GitHub/bitcoin/depends'

real	4m22,359s
user	18m3,719s
sys     1m24,769s

this PR:

$ time make -j 9 -C depends/ qt
...
Caching qt...
make: Leaving directory '/home/hebasto/guix/GitHub/bitcoin/depends'

real	4m14,862s
user	18m3,355s
sys 	1m24,506s

Qt docs: https://doc.qt.io/qt-5/qmake-precompiledheaders.html

Fixes #20423

DrahtBot added the label Build system on Nov 27, 2020
DrahtBot commented at 1:51 AM on November 28, 2020: member



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Conflicts

No conflicts as of last run.
MarcoFalke commented at 8:46 AM on November 28, 2020: member

This effectively reverts commit 9267a47d86d0673eae9e504ee566aa4e0410d923 by @theuni

review ACK b1f35876e91b3422a8f8c4ac4d1f389b72132c62 because this enables the GUI build again for i686, haven't checked the performance
fanquake commented at 8:35 AM on November 30, 2020: member

@hebasto can you post the log of the qt build failure when using -pch? Do you know what has changed between CentOS 7 & 8 that is causing the issue?

Is using -pch still a problem when building newer Qt? i.e 5.15.x If the problem is just with CentOS, can we disable pch for Linux Qt builds, rather than wholesale?

hebasto commented at 5:39 PM on November 30, 2020: member

can you post the log of the qt build failure when using -pch?

$ make -C depends qt
...
Running configuration tests...
...
Checking for precompiled header support... 
+ cd /home/hebasto/bitcoin/depends/work/build/x86_64-pc-linux-gnu/qt/5.9.8-991caec5731/qtbase/config.tests/common/pch && PKG_CONFIG_SYSROOT_DIR=/ PKG_CONFIG_LIBDIR=/home/hebasto/bitcoin/depends/x86_64-pc-linux-gnu/lib/pkgconfig /home/hebasto/bitcoin/depends/work/build/x86_64-pc-linux-gnu/qt/5.9.8-991caec5731/qtbase/bin/qmake "CONFIG -= qt debug_and_release app_bundle lib_bundle" "CONFIG += static warn_off console single_arch" -early "CONFIG += cross_compile" /home/hebasto/bitcoin/depends/work/build/x86_64-pc-linux-gnu/qt/5.9.8-991caec5731/qtbase/config.tests/common/pch
+ cd /home/hebasto/bitcoin/depends/work/build/x86_64-pc-linux-gnu/qt/5.9.8-991caec5731/qtbase/config.tests/common/pch && MAKEFLAGS= /usr/bin/gmake
> gmake[1]: Entering directory '/home/hebasto/bitcoin/depends/work/build/x86_64-pc-linux-gnu/qt/5.9.8-991caec5731/qtbase/config.tests/common/pch'
> g++ -m64 -pipe -pipe -O2 -I/home/hebasto/bitcoin/depends/x86_64-pc-linux-gnu/include -O2 -w -fPIC  -I. -I/home/hebasto/bitcoin/depends/work/build/x86_64-pc-linux-gnu/qt/5.9.8-991caec5731/qtbase/mkspecs/linux-g++-64 -x c++-header -c header.h -o .pch/pch.gch/c++
> g++ -c -include .pch/pch -m64 -pipe -pipe -O2 -I/home/hebasto/bitcoin/depends/x86_64-pc-linux-gnu/include -O2 -w -fPIC  -I. -I/home/hebasto/bitcoin/depends/work/build/x86_64-pc-linux-gnu/qt/5.9.8-991caec5731/qtbase/mkspecs/linux-g++-64 -o source.o source.cpp
> cc1plus: error: one or more PCH files were found, but they were invalid
> cc1plus: error: use -Winvalid-pch for more information
> cc1plus: fatal error: .pch/pch: No such file or directory
> compilation terminated.
> gmake[1]: *** [Makefile:183: source.o] Error 1
> gmake[1]: Leaving directory '/home/hebasto/bitcoin/depends/work/build/x86_64-pc-linux-gnu/qt/5.9.8-991caec5731/qtbase/config.tests/common/pch'
test config.qtbase.tests.precompile_header FAILED
...
ERROR: Feature 'precompile_header' was enabled, but the pre-condition 'config.msvc || tests.precompile_header' failed.
make: *** [funcs.mk:268: /home/hebasto/bitcoin/depends/work/build/x86_64-pc-linux-gnu/qt/5.9.8-991caec5731/qtbase/.stamp_configured] Error 3
make: Leaving directory '/home/hebasto/bitcoin/depends'

Do you know what has changed between CentOS 7 & 8 that is causing the issue?

Compiler? CentOS 8 has gcc 8.3.1.

MarcoFalke commented at 10:48 AM on December 2, 2020: member

Anything left do do here? Disabling the gui cross compilation was only a temporary hack and it should be enabled again at the earliest convenience

depends: Do not force Precompiled Headers (PCH) for building Qt on Linux

On CentOS 8 the forced '-pch' option breaks Qt build.
Removing '-pch' option does not affect build time for other Linux
systems.

c82d15b6d1

hebasto force-pushed on Dec 2, 2020
hebasto renamed this:
~~ci, depends: Do not force Precompiled Headers (PCH) when building Qt~~
depends: Do not force Precompiled Headers (PCH) when building Qt
on Dec 2, 2020
hebasto renamed this:
~~depends: Do not force Precompiled Headers (PCH) when building Qt~~
depends: Do not force Precompiled Headers (PCH) for building Qt on Linux
on Dec 2, 2020
hebasto commented at 11:53 AM on December 2, 2020: member
Updated b1f35876e91b3422a8f8c4ac4d1f389b72132c62 -> c82d15b6d189983ebf82f35ade33d830870f25c6 (pr20520.01 -> pr20520.02, diff):
- addressed @fanquake's comment:
If the problem is just with CentOS, can we disable pch for Linux Qt builds, rather than wholesale?
MarcoFalke commented at 4:27 PM on December 2, 2020: member

review ACK c82d15b6d189983ebf82f35ade33d830870f25c6

I liked the simplicity of the first patch, but this looks fine, too
laanwj commented at 12:22 PM on December 3, 2020: member

This effectively reverts commit 9267a47 by @theuni

I'm confused as to why this is suddenly broken. This patch is from 2016 !

That said, merging this even as a temporary workaround makes sense.
laanwj merged this on Dec 3, 2020
laanwj closed this on Dec 3, 2020
hebasto deleted the branch on Dec 3, 2020
DrahtBot locked this on Feb 15, 2022

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#20423 build: Re-enable i686 qt build on centos 8 #28365 ci: error: one or more PCH files were found, but they were invalid

depends: Do not force Precompiled Headers (PCH) for building Qt on Linux #20520

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