[ruby-core:107229] [Ruby master Bug#18249] The ABI version of dev builds of CRuby does not correspond to the ABI

["Eregon (Benoit Daloze)" <noreply@ruby-lang.org>]

Issue #18249 has been updated by Eregon (Benoit Daloze).

Status changed from Rejected to Open

naruse (Yui NARUSE) wrote in #note-9:
> For dev builds, Ruby switchers has responsibility to handle the ABI compatibility breakage.
> CRuby developers don't want to manage the compatibility. (We don't invest our resource here)

@naruse There is a PR doing the work, and it requires no effort from CRuby dev, how is this a problem?
Without this fix, it is a common issue for both CRuby dev and for users which try ruby-head (e.g., to try to keep their gem compatible with it).
It's a mistake to close this issue without a good reason, so I reopen, and of course it can be discussed at the dev meeting.

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Bug #18249: The ABI version of dev builds of CRuby does not correspond to the ABI
https://bugs.ruby-lang.org/issues/18249#change-96089

* Author: Eregon (Benoit Daloze)
* Status: Open
* Priority: Normal
* Backport: 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN
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In fact, it even conflicts with the next release's ABI version:
```
$ ruby -ve 'p RbConfig::CONFIG["ruby_version"]'
ruby 3.1.0dev (2021-10-11T10:13:16Z master 0c3ac87345) [x86_64-linux]
"3.1.0"
```

This mismatch can very easily result in segfaults, memory corruption, etc when using dev versions of CRuby,
or when using a dev version and then later the release.

Possible solutions:
* Include the git commit sha in the ABI. Pros: always correct and simple. Cons: changing more then necessary.
* Track the ABI explicitly, and bump it whenever the ABI changes. Pros: changes only when needed. Cons: easy to forget bumping it, and if checked in CI already too late.

From https://bugs.ruby-lang.org/issues/18239#note-14:

FWIW TruffleRuby actually tracks the ABI of dev versions through [this file](https://github.com/oracle/truffleruby/blob/master/lib/cext/ABI_version.txt) which means it is possible to sensibly cache compiled gems even for dev versions [details](https://github.com/oracle/truffleruby/issues/2284).
Also it [stores](https://github.com/oracle/truffleruby/commit/d497bae73fdc60585b66cd183768a16563b2886b) the ABI version in .so/.bundle files and checks them when loading, so it can be sure the ABI used to compile and runtime ABI match (if not, an exception is raised).

ruby/setup-ruby has no choice for CRuby dev but [to use the commit](https://github.com/ruby/setup-ruby/blob/a6f22865941e122a37e097fbded3dd0b54c39207/bundler.js#L188) as the ABI version.
This issue is made worse by Ruby switchers like RVM & chruby setting GEM_HOME (so the ABI is effectively ignored by RubyGems in those cases, and those directories need to be cleaned manually).
When GEM_HOME is not set, it would be enough to rebuild CRuby dev and remove the directory before installing (which includes both CRuby & gems), but Ruby installers don't do that yet.
Bundler always includes the ABI version when setting the bundler path (`bundle config --local path`), but if the ABI version is incorrect like for CRuby dev it's of no use.



-- 
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