Fix boolean parameters without value with following comment

[tagomoris]

As reported at tagomoris/fluent-plugin-route#10, config_param :name, :bool returns falsely value (nil) when it's configured without explicit value with following comment.

# parameter definition
config_param :b1, :bool, default: false
config_param :b2, :bool, default: false

# configuration
# b1 will be true
b1
# b2 will be nil
b2 # comment here

This bug cannot be reproducible via test cases of v1 parser, but I succeeded to reproduce it using plugin code and test driver. This bug was reported to be reproducible on actual Fluentd processes.

[tagomoris]

@repeatedly This looks a bug related with literal parser, v1 parser and value parser, and takes a time to fix it. Could you take ownership on this?

[repeatedly]

The problem is this line:

fluentd/lib/fluent/config/v1_parser.rb

Line 108 in 7c0c012

spacing_without_comment

Maybe, this is for this test case:

fluentd/test/config/test_config_parser.rb

Line 97 in 7c0c012

assert_text_parsed_as(e('ROOT', '', {"k1" => "#not_comment"}), " k1 #not_comment")

I think this parsed result should be {"k1" => ""} because we can use '# foo' like syntax for # started string. But changing this behaviour may break existing environment. So we can't use this fix.
For keeping compatibility, changing bool handling is better.

diff --git a/lib/fluent/config/types.rb b/lib/fluent/config/types.rb
index f41d451..beccc18 100644
--- a/lib/fluent/config/types.rb
+++ b/lib/fluent/config/types.rb
@@ -60,7 +60,11 @@ module Fluent
       when ''
         true
       else
-        nil
+        if str.start_with?('#')
+          true
+        else
+          nil
+        end
       end
     end

[repeatedly]

Hmm... return nil seems error prone. Should it raise an exception for unexpected value?

[repeatedly]

@tagomoris How about this patch?