Bug 623364 – dev-qt/qtwebengine-5.7.1-r1 - SEGV_MAPERR when built with GCC 6.3

• Product: Gentoo Linux
• Status: RESOLVED CANTFIX

[Description Daniele 2017-07-01 19:33:04 UTC]

Created attachment 479156 [details]
TraceBack of the render crash

After building the latest webengine using GCC 6.3, I found that all the browsers based on this engine have their rendering process crash.

After a bit of research, it seems it could be due to GCC 6.3's Pointer Check optimization.

Here's the link to the changes page of GCC for ease of access

https://gcc.gnu.org/gcc-6/changes.html

I'm attaching the (probably useless) traceback I get from the rendering crash.

Thank you for your attention.

[Comment 1 Andreas Sturmlechner 2017-07-01 20:04:55 UTC]

emerge --info.......?

[Comment 2 Daniele 2017-07-01 20:11:39 UTC]

Created attachment 479222 [details]
emerge --info

[Comment 3 Daniele 2017-07-01 20:12:03 UTC]

My apologies, I have no idea why I forgot it this time.

[Comment 4 Daniele 2017-07-04 07:25:39 UTC]

I tried rebuilding qtWebEngine as suggested by the GCC link, it seems that it didn't work.
I'm going to merge it with USE+="debug" hoping to get a better traceback.

[Comment 5 Daniele 2017-07-24 07:18:58 UTC]

Seems that I did a typo in the build flags while trying to rebuild QtWebEngine, a seemingly working workaround is adding

-fno-delete-null-pointer-checks

to CFLAGS and CXXFLAGS

I did so in my make.conf and rebuilt qtwebengine with

emerge -1 qtwebengine

Had no crashes so far.

[Comment 6 jms 2017-09-19 11:27:18 UTC]

Created attachment 495396 [details]
emerge --info

Portage 2.3.8 (python 3.4.5-final-0, default/linux/amd64/13.0/desktop/plasma, gcc-6.4.0, glibc-2.23-r4,

[Comment 7 jms 2017-09-19 17:12:09 UTC]

had the same problem with
dev-qt/qtwebengine-5.7.1-r2
kde-apps/akonadi-17.08.1
kde-apps/libkgapi-17.08.1

when attempting to add a new gmail account
the authentication screen appear briefly then become banlk/grey
not possible to authenticate via interface rendered  I suppose by qtwebengine.
rebuilding libkgapi akonadi libkdepim kdepim-runtime kdepim-addons
did not help

rebuilding QtWebEngine with 

-fno-delete-null-pointer-checks

to CFLAGS and CXXFLAGS

in make.conf and rebuilding qtwebengine with

emerge -1 qtwebengine

did solve the problem
thanks to Daniele

please note I didn't try to rebuild 
dev-qt/qtwebengine-5.7.1-r2 without -fno-delete-null-pointer-checks  added to to CFLAGS and CXXFLAGS

[Comment 8 jms 2017-09-19 20:46:08 UTC]

did try rebuilding without -fno-delete-null-pointer-checks
won't work
seems you need to have -fno-delete-null-pointer-checks 
for dev-qt/qtwebengine-5.7.1-r2 to works properly with gcc-6.4.0
(at least in order to be able to authenticate) gmail account with kmail/libkgapi)

[Comment 9 Michael Palimaka (kensington) 2019-04-18 09:55:40 UTC]

<GCC-6.4 is masked