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| author |   Michał Górny <mgorny@gentoo.org> | 2020-01-08 10:21:50 +0100 |
|---|---|---|
| committer | Michał Górny <mgorny@gentoo.org> | 2020-01-08 10:41:07 +0100 |
| commit | 0c7ca4fd8cc70fe65c0898bc2365cef5f8a22012 (patch) | |
| tree | 8bacf7ffdd2599fdbeccbe2ae2759231367d5ad0 | |
| parent | Optional RDEPEND policy (diff) | |
| download | policy-guide-0c7ca4fd8cc70fe65c0898bc2365cef5f8a22012.tar.gz policy-guide-0c7ca4fd8cc70fe65c0898bc2365cef5f8a22012.tar.bz2 policy-guide-0c7ca4fd8cc70fe65c0898bc2365cef5f8a22012.zip | |
USE=multislot policy
Signed-off-by: Michał Górny <mgorny@gentoo.org>
| -rw-r--r-- | other-metadata.rst | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/other-metadata.rst b/other-metadata.rst new file mode 100644 index 0000000..ddc8377 --- /dev/null +++ b/other-metadata.rst @@ -0,0 +1,39 @@ +Other metadata variables +======================== + +.. index:: SLOT; dynamic +.. index:: USE flags; multislot + +Dynamic slots (multislot flag) +------------------------------ +:Source: QA (inferred from PMS) +:Reference: https://wiki.gentoo.org/index.php?title=Project:Quality_Assurance/Policies&oldid=109991#multislot.2FUSE-dependent_SLOT +:Reported: ``use`` in global scope triggers fatal error + +The use of ``multislot`` to alter ``SLOT`` values (as well as any other +USE-dependent slot values) in the Gentoo repository is forbidden. +Such a feature can be used in overlays, and it is acceptable to provide +such support in eclasses as long as it is not used in ::gentoo. + +This policy has been explicitly declared in response to historical +(pre-2016) use of ``USE=multislot`` in toolchain ebuilds. When the flag +was disabled, all package versions used the same slot, and upgrades were +handled as for non-slotted packages. When the flag was enabled, each +version used a separate slot, permitting multiple versions being +installed simultaneously. This allowed the user to choose between +the two options. + +The original violation has been resolved by unconditionally slotting +the packages. This permitted the users to install multiple versions +in parallel, while removal of old versions was to be handled via +``emerge --depclean``. + +*Rationale*: this feature was in direct violation of PMS `metadata +invariance`_ requirements. It caused the cached slot value to depend +on the state of querying the USE flag (which in turn could technically +depend on slot, via ``package.use``). This caused undefined package +manager behavior which could include use of unpredictable slot, cache +invalidation or explicit errors. + + +.. _metadata invariance: https://projects.gentoo.org/pms/7/pms.html#x1-600007.1 |