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Issue 642641 link

Starred by 2 users

Issue metadata

Status: Duplicate
Merged: issue 588513
Owner: ----
Closed: Aug 2016
Cc:
Components:
EstimatedDays: ----
NextAction: ----
OS: ----
Pri: 1
Type: Bug



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GN: changes to build_overrides constantly break downstream projects

Project Member Reported by machenb...@chromium.org, Aug 31 2016

Issue description

V8 stand-alone automatically updates //build as a dependency with an auto-roller.

This approach breaks now daily because changes in //build depend on new identifiers in build_overrides and creates disturbing porting work.

Examples:
https://codereview.chromium.org/2267753002 broke
https://codereview.chromium.org/2289063002

https://codereview.chromium.org/2293853002 broke
https://codereview.chromium.org/2293333002/

Suggestions:
1) Only read the values from build_overrides guarded by a "defined" check and use meaningful defaults if undefined.
2) Make folks land dependent CLs in subrepos first (not a very local approach).
3) Change the build_override mechanism so that it is truly "override". I.e. allow optionally overriding a given default. Currently we have to specify a (possibly different) default everywhere.

1 and 2 would be rather social attempts, i.e. only lgtm CLs that take care of this.
 
Mergedinto: 588513
Status: Duplicate (was: Untriaged)
more accurately, "daily" == ~4 times a month :).

But, yeah, this approach isn't ideal. 

I think this is more-or-less a dup of  bug 588513 .
2 times in 2 days :)

This is only a dup IMO if we change the mechanism. The suggestions 1 and 2 could be taken care of independently, but it's merely a process thing that reviewers and owners should remember, i.e. no action required here.

I also thought about if it's possible to run gn on the chromium side in an as-if-it's-v8-stand-alone kind of way. Just running gn only takes milliseconds, the problem is the current directory arrangement of the deps... I wonder if we could simply simulate the v8 stand-alone layout with a set of hard-links on linux...


Yes, the intent is to change the mechanism, because the current mechanism is clearly both awkward and flawed.

I'm not sure how running gn on the chromium side would help things, unless you're hoping that we would catch breakages? I don't think the breakages were a surprise, since every time you add something to build_overrides things'll break (or at least need to be manually rolled).
Checking it on the chromium-side would move the manual work-load from the subrepo maintainers to the feature developer (i.e. the dev that adds new things to build_overrides). But I guess this doesn't scale well - just as little as the current approach.

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