[GR-17818] List members for String and Symbol.

PullRequest: truffleruby/1171

Author: pitr-ch

CHANGELOG.md

@@ -35,6 +35,7 @@ Bug fixes:
 * Fixed issue in `ConditionVariable#wait` that could lose a `ConditionVariable#signal`.
 * Do not leak TruffleRuby specific method Array#swap (#1816)
 * Fixed `#inspect` on broken UTF-8 sequences (#1842, @chrisseaton).
+* `Truffle::Interop.keys` should report methods of String and Symbol (#1817)
 
 Compatibility:
 

src/main/ruby/truffleruby/core/truffle/interop.rb

@@ -44,7 +44,7 @@ def self.object_keys(object, internal)
       # TODO (pitr-ch 23-May-2019): add assert that called methods are in members list
       if object.is_a?(Hash)
         keys = object.keys # FIXME (pitr-ch 11-May-2019): no return methods
-      elsif object.respond_to?(:[]) && !object.is_a?(Array)
+      elsif object.respond_to?(:[]) && !object.is_a?(Array) && !object.is_a?(String) && !object.is_a?(Symbol)
         # FIXME (pitr-ch 11-May-2019): remove the branch
         keys = []
       else