1329044 - Compiler bug in gcc <7.0 in TexUnpackSurface code (const auto& doesn't properly bind a scalar member of a temporary)

Status: RESOLVED FIXED

(Core :: Graphics: CanvasWebGL, defect)

Description

[Dzmitry Malyshau [:kvark]]

> however, gcc versions earlier than 7 have a bug where this lifetime extension is not implemented for subobjects of scalar type: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54293

This applies to several cases in TexUnpackSurface implementation, like this one:
> const auto& rowLength = mSurf->GetSize().width;

Comment 1

[Dzmitry Malyshau [:kvark]]

Attachment: webgl-texunpackblob-ub.patch

Comment 2

[Dzmitry Malyshau [:kvark]]

Treherder status:
https://treeherder.mozilla.org/#/jobs?repo=try&revision=25e6e1687d4b1910327e4457cd1781841496fcd5

Comment 3

[Carsten Book [:Tomcat]]

need first a positive review before we can check this in

Comment 4

[Dzmitry Malyshau [:kvark]]

Attachment: Avoid taking const references to fields behind accessors.

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/d54ebcd1a796
Avoid taking const references to fields behind accessors. r=jgilbert

Comment 6

[Kelsey Gilbert [:jgilbert]]

Comment on attachment 8825105 [details] [diff] [review]
Avoid taking const references to fields behind accessors.

Approval Request Comment
[Feature/Bug causing the regression]: 
[User impact if declined]: Incorrect behavior on GCC builds. (Linux)
[Is this code covered by automated tests?]:
[Has the fix been verified in Nightly?]:
[Needs manual test from QE? If yes, steps to reproduce]: 
[List of other uplifts needed for the feature/fix]:
[Is the change risky?]: No risk.
[Why is the change risky/not risky?]: Trivial change.
[String changes made/needed]: none

Comment 7

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/d54ebcd1a796

Comment 8

[Julien Cristau [:jcristau]]

Comment on attachment 8825105 [details] [diff] [review]
Avoid taking const references to fields behind accessors.

workaround gcc bug affecting webgl, aurora52+, beta51+

Comment 9

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/releases/mozilla-aurora/rev/b1207646a147

Comment 10

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/releases/mozilla-beta/rev/95d20a617288