Gentoo Archives: gentoo-dev

From: "Michał Górny" <mgorny@g.o>
To: gentoo-dev@l.g.o
Subject: [gentoo-dev] [RFC] Un-slotting LLVM
Date: Mon, 08 Nov 2021 11:18:41
1 Hi,
3 A few years back I've slotted LLVM and Clang to make the life with
4 revdeps easier. Long story short, every major LLVM release (which
5 happens twice a year) breaks API and it takes some time for revdeps to
6 adjust. Slotting made it possible to install multiple versions
7 simultaneously, and therefore let "faster" packages use newer LLVM
8 without being blocked by "slower" packages on the user's system.
10 Unfortunately, this ended up pretty bothersome to maintain. Besides
11 making ebuilds quite complex (and prone to mistakes), I'm hearing more
12 and more reports of programs being broken through getting multiple LLVM
13 versions in the link chain.
15 This is not something that can be easily solved. In other words, it's
16 a mess and I don't think we're really getting anywhere. For this
17 reason, I'm considering dropping slotting and going back to permitting
18 only a single version of LLVM and Clang being installed.
20 This would have two major implications:
22 1. If you installed any package that requires older LLVM, it'd block all
23 other packages from updating. If you hit two packages that do not have
24 a common supported LLVM version, you won't be able to install them
25 at all.
27 On the plus side, this will motivate developers to actually start fixing
28 these packages rather than letting them rot until I start removing old
29 LLVM versions.
31 2. We will no longer support having multiple clang versions installed.
32 While it was convenient for testing stuff, it's not really a killer
33 feature though.
35 The only real alternative I see is actively limiting supported LLVM
36 versions in packages to ensure that all libraries in the depgraph end up
37 using the same LLVM version. However, I don't think it's really worth
38 the effort.
40 I don't have a ready unslotting plan yet.
42 WDYT?
44 --
45 Best regards,
46 Michał Górny


Subject Author
Re: [gentoo-dev] [RFC] Un-slotting LLVM Florian Schmaus <flow@g.o>
Re: [gentoo-dev] [RFC] Un-slotting LLVM "Luke A. Guest" <laguest@×××××××.com>
Re: [gentoo-dev] [RFC] Un-slotting LLVM Gerion Entrup <gerion.entrup@×××××.de>
Re: [gentoo-dev] [RFC] Un-slotting LLVM Georgy Yakovlev <gyakovlev@g.o>
Re: [gentoo-dev] [RFC] Un-slotting LLVM Sam James <sam@g.o>
Re: [gentoo-dev] [RFC] Un-slotting LLVM "Michał Górny" <mgorny@g.o>