Bug 632598

Summary:	sys-apps/portage: --autounmask USE changes can trigger unnecessary backtracking
Product:	Portage Development	Reporter:	Zac Medico <zmedico>
Component:	Core - Dependencies	Assignee:	Portage team <dev-portage>
Status:	RESOLVED FIXED
Severity:	normal	CC:	esigra
Priority:	Normal	Keywords:	InVCS
Version:	unspecified
Hardware:	All
OS:	All
See Also:	https://bugs.gentoo.org/show_bug.cgi?id=628004
Whiteboard:
Package list:		Runtime testing required:	---
Bug Depends on:
Bug Blocks:	376695, 631448

Description Zac Medico gentoo-dev

2017-10-01 00:49:48 UTC

The want_restart_for_use_change function it overly eager to trigger backtracking in some cases where there are USE dependencies in the graph. The problem is right here, where want_restart_for_use_change returns True for any overlapping USE dependencies, even though those USE dependencies may be satisfied with the changes:

new_use, changes = self._dynamic_config._needed_use_config_changes.get(pkg)
for ppkg, atom in parent_atoms:
	if not atom.use or \
		not any(x in atom.use.required for x in changes):
		continue
	else:
		return True

I discovered this issue while working on GLEP 73 support (bug 628004), since autounmask USE changes make trigger REQUIRED_USE changes, and we want to avoid backtracking here whenever possible.

Comment 1 Zac Medico gentoo-dev

2017-10-01 03:05:01 UTC

Patch posted for review:

https://archives.gentoo.org/gentoo-portage-dev/message/9a623ecbaac654ee389004d3da80f6a5
https://github.com/gentoo/portage/pull/212

Comment 2 Zac Medico gentoo-dev

2017-10-02 19:06:24 UTC

This is in the master branch:

https://gitweb.gentoo.org/proj/portage.git/commit/?id=d39e0532674d78436e78c035143163001dbb198f

Comment 3 Zac Medico gentoo-dev

2017-10-02 19:37:24 UTC

Released in 2.3.11.