Issue #21795 has been updated by Eregon (Benoit Daloze). I asked Codex to analyze how stable are `node_id` across Prism versions and the answer is it's not stable: https://gist.github.com/eregon/469e40f447f6edac813a389e7f3f4832 One interesting fact is that `node_id` tracks the internal node allocation order in Prism and simple optimizations to e.g. use less temporary nodes can change the given `node_id`s, for example ```ruby A = 1 def target end ``` does not have a `node_id` 2 because that's taken by a temporary node, more details at https://gist.github.com/eregon/469e40f447f6edac813a389e7f3f4832#temporary-no... I don't think it's reasonable to prevent these optimizations forever to keep `node_id` stable. It's also easy to change `node_id`s unknowingly as detailed there, and it has happened many times already. IOW I think a warning is not gonna cut it here, and there would be cases of returning the wrong node in practice. ---------------------------------------- Feature #21795: Methods for retrieving ASTs https://bugs.ruby-lang.org/issues/21795#change-118226 * Author: kddnewton (Kevin Newton) * Status: Open ---------------------------------------- I would like to propose a handful of methods for retrieving ASTs from various objects that correspond to locations in code. This includes: * Proc#ast * Method#ast * UnboundMethod#ast * Thread::Backtrace::Location#ast * TracePoint#ast (on call/return events) The purpose of this is to make tooling easier to write and maintain. Specifically, this would be able to be used in irb, power_assert, error_highlight, and various other tools both in core and not that make use of source code. There have been many previous discussions of retrieving node_id, source_location, source, etc. All of these use cases are covered by returning the AST for some entity. In this case node_id becomes an implementation detail, invisible to the user. Source location can be derived from the information on the AST itself. Similarly, source can be derived from the AST. Internally, I do not think we have to store any more information than we already do (since we have node_id for the first four of these, it becomes rather trivial). For TracePoint we can have a larger discussion about it, but I think it should not be too much work. In terms of implementation, the only caveat I would put is that if the ISEQ were compiled through the old parser/compiler, this should return `nil`, as the node ids do not match up and we do not want to further propagate the RubyVM::AST API. The reason I am opening up this ticket with 5 different methods requested in it is to get approval first for the direction, then I can open individual tickets or just PRs for each method. I believe this feature would ease the maintenance burden of many core libraries, and unify otherwise disparate efforts to achieve the same thing. -- https://bugs.ruby-lang.org/