From: "kddnewton (Kevin Newton) via ruby-core" Date: 2025-10-08T12:51:11+00:00 Subject: [ruby-core:123431] [Ruby Bug#21618] Allow to use the build-in prism version to parse code Issue #21618 has been updated by kddnewton (Kevin Newton). I don't think these are theoretical concerns at all ��� this issue has bothered me since we shipped prism initially to be honest. @k0kubun put it pretty succinctly in his note on this issue: https://bugs.ruby-lang.org/issues/19772#note-16. We went with option 3, but this ticket is suggesting we go with option 4. I would very much like to solve this by exposing the exact C API that the current Ruby runtime is exposing, but I haven't quite figured out how yet. The closest I have come to a compromise of the various concerns would be to version the nodes such that we only need a new constant for the ones that change, but I haven't finished thinking about that yet. Like maybe the serialization format contains a version integer at the beginning? The other issue discussed in here is that prism defaults to the latest Ruby syntax version. That was an intentional choice ��� the first thing I was building with this was a formatter, and I wanted it to understand the latest syntax no matter what the currently running version of Ruby was. I am actually open to changing this, but it will have to be in a major version, and that's something we can just discuss on the ruby/prism issue tracker instead of here since it doesn't impact ruby/ruby. ---------------------------------------- Bug #21618: Allow to use the build-in prism version to parse code https://bugs.ruby-lang.org/issues/21618#change-114801 * Author: Earlopain (Earlopain _) * Status: Open * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- Prism is a multi-version parser, which is a great feature. If one calls `Prism.parse("foo")`, it will always use the latest version prism knows about. This may or may not be the version that is currently executing. This is problematic when one wants to introspect code the same way that the currently running ruby version would. Consider that some syntax will be disallowed in the next ruby version. I would have to specify the ruby version I want to parse as in order to not run into syntax errors: `Prism.parse("foo", version: RUBY_VERSION)`. But doing so is not feasable because `prism` is distributed out of sync with ruby itself. If the user already has prism in their lockfile, the user may run a prism version that doesn't yet know about lets say ruby 4.0 and thus raise. Similarly, it may parse as an older patch version that has subtle behaviour differences. `ripper` does not have this issue because it is always tied to the ruby version and it is not distributed as a gem, so what the user has will always be exactly what ruby shipped with. I wish for a similar API that utilizes the prism version bundled with ruby itself. Libraries like `rails` have moved from ripper to prism because of its superior developer experience but it risks breaking in unexpected ways with new `prism` versions that know about more recent syntax. `error_highlight` for example also suffers from the same defect. It seems like prism currently has 34 methods that optionally take a version (per the rbi file). Many of these are trivial helper methods like `Prism.parse_success?` (does the parse result have any errors?). I would be happy with supporting only the minimal functions like `Prism.parse` and `Prism.parse_file`. Currently I don't have a use-case for any of the other methods. Pretty much just functions to mirror `RubyVM::InstructionSequence.compile_file` and `RubyVM::InstructionSequence.compile`. It would be optimal if I would be able to transparently call `Prism.parse("foo", version: "current")` (or maybe even have an unspecified version mean the build-in prism version) but I am not sure how feasable that is since I'm pretty sure logic for this would have to live in ruby itself. @kddnewton does this feature request make sense? Do you have any other ideas/inputs? -- https://bugs.ruby-lang.org/ ______________________________________________ ruby-core mailing list -- ruby-core@ml.ruby-lang.org To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org ruby-core info -- https://ml.ruby-lang.org/mailman3/lists/ruby-core.ml.ruby-lang.org/