Ignore any encoding errors while symbol completion

Author: nobu

lib/irb/completion.rb

@@ -192,7 +192,7 @@ def self.retrieve_completion_data(input, bind: IRB.conf[:MAIN_CONTEXT].workspace
         sym = $1
         candidates = Symbol.all_symbols.collect do |s|
           ":" + s.id2name.encode(Encoding.default_external)
-        rescue Encoding::UndefinedConversionError
+        rescue EncodingError
           # ignore
         end
         candidates.grep(/^#{Regexp.quote(sym)}/)

test/irb/test_completion.rb

@@ -27,6 +27,10 @@ def test_complete_numeric
     end
 
     def test_complete_symbol
+      %w"UTF-16LE UTF-7".each do |enc|
+        "K".force_encoding(enc).to_sym
+      rescue
+      end
       _ = :aiueo
       assert_include(IRB::InputCompletor.retrieve_completion_data(":a", bind: binding), ":aiueo")
       assert_empty(IRB::InputCompletor.retrieve_completion_data(":irb_unknown_symbol_abcdefg", bind: binding))