From: merch-redmine@... Date: 2020-08-28T21:35:03+00:00 Subject: [ruby-core:99759] [Ruby master Bug#16983] RubyVM::AbstractSyntaxTree.of(method) returns meaningless node if the method is defined in eval Issue #16983 has been updated by jeremyevans0 (Jeremy Evans). I'm not sure if this is a bug, but it does seem like a fundamental and significant limitation with the design of RubyVM::AbstractSyntaxTree.of. RubyVM::AbstractSyntaxTree.of reparses the file the method is defined in and cannot handle any cases where `eval` or similar are used. You'll get a node completely different from what you would expect. Here's another example: ```ruby eval DATA.read, binding, __FILE__, 14 method = method(:foo) pp RubyVM::AbstractSyntaxTree.of(method) __END__ def foo end ``` Output: ``` (VCALL@1:16-1:23 :binding) ``` Because it reparses the file, you'll also get the wrong result if the file is modified: ```ruby def bar end File.write(__FILE__, File.read(__FILE__).gsub('def bar', "def foo\nbar")) method = method(:bar) pp RubyVM::AbstractSyntaxTree.of(method) ``` Output: ``` (SCOPE@1:0-3:3 tbl: [] args: (ARGS@1:7-1:7 pre_num: 0 pre_init: nil opt: nil first_post: nil post_num: 0 post_init: nil rest: nil kw: nil kwrest: nil block: nil) body: (VCALL@2:0-2:3 :bar)) ``` And if the interpreter can no longer access the file (chroot, file deletion, permission change, or other file system access limiting), you get an error. I can't think of a way to fix this without all iseq methods holding a reference to the string used to parse them, and having RubyVM::AbstractSyntaxTree.of work off that string. I'm not sure how much extra memory use that would cause, or if such an approach is considered acceptable. ---------------------------------------- Bug #16983: RubyVM::AbstractSyntaxTree.of(method) returns meaningless node if the method is defined in eval https://bugs.ruby-lang.org/issues/16983#change-87263 * Author: pocke (Masataka Kuwabara) * Status: Open * Priority: Normal * ruby -v: ruby 2.8.0dev (2020-06-23T13:58:26Z master dc351ff984) [x86_64-linux] * Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN ---------------------------------------- # Problem `RubyVM::AST.of(method)` returns a meaningless node if the method is defined in eval. For example: ```ruby p 'blah' eval <<~RUBY, binding, __FILE__, __LINE__ + 1 def foo end RUBY method = method(:foo) pp RubyVM::AbstractSyntaxTree.of(method) # => (STR@3:5-3:12 "def foo\n" + "end\n") ``` I expect the node of `foo` method, or `nil`. But it returns a `STR` node. It becomes a big problem when `AST.of` receives arbitrary methods. Because we can't distinguish a method is defined in `eval` or not. It means we can't believe the returned value of `AST.of` if the method may receive a method defined in `eval`. For example: ```ruby def do_something_for_each_method_ast(klass) klass.instance_methods(false).each do |m| ast = RubyVM::AbstractSyntaxTree.of(klass.instance_method(m)) next unless ast do_something ast end end class A eval <<~RUBY, binding, __FILE__, __LINE__ + 1 def foo end RUBY end do_something_for_each_method_ast A ``` In the example, I expect the `do_something` method receives only node for a method definition, but it may pass a wrong node if any method is defined in `eval`. # Cause (I guess) I guess the cause is misleading node number. In and out of an `eval` block uses different sequences of node number. So if I specify `__FILE__` to `eval`, the actual file and code in `eval` may have the same node number. For example ```ruby p 'blah' # Node number for 'blah' is 1, file name is "test.rb" eval <<~RUBY, binding, __FILE__, __LINE__ + 1 def foo # Node number for `def` is also 1, file name is also "test.rb" end RUBY method = method(:foo) # It finds a node from node number 1 by reading "test.rb", so it get the str node. pp RubyVM::AbstractSyntaxTree.of(method) # => (STR@3:5-3:12 "def foo\n" + "end\n") ``` -- https://bugs.ruby-lang.org/ Unsubscribe: