Bug #16983
closedRubyVM::AbstractSyntaxTree.of(method) returns meaningless node if the method is defined in eval
Description
Problem¶
RubyVM::AST.of(method)
returns a meaningless node if the method is defined in eval.
For example:
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:
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
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")