comment out works only after /[ \t]+#/ in nonquoted string

example/v1_literal_example.conf

@@ -22,3 +22,15 @@
   key9  "#{test}"  # replaced by eval('test')
   key10 "\\[(?<time>[^\\]]*)\\] (?<message>.*)" # \[(?<time>[^\]]*\] (?<message>.*)
 </section2>
+<section3>
+  key1  text     # text
+  key2  \        # \ (1 char)
+  key3  \\       # \\ (2 char)
+  key4  \t       # \t (2 char)
+  key5  \[       # \[ (2 char)
+  key6  \\[      # \\[ (3 char)
+  key7  #t       # #t (2 char)
+  key8  \#{test} # \#{test} (8 char)
+  key9  #{test}  # #{test} (7 char)
+  key10 \[(?<time>[^\]]*)\] (?<message>.*)    # \[(?<time>[^\]]*\] (?<message>.*)
+</section3>

lib/fluent/config/basic_parser.rb

@@ -27,6 +27,7 @@ def initialize(strscan)
 
       LINE_END = /(?:[ \t]*(?:\#.*)?(?:\z|[\r\n]))+/
       SPACING = /(?:[ \t\r\n]|\z|\#.*?(?:\z|[\r\n]))+/
+      SPACING_WITHOUT_COMMENT = /(?:[ \t\r\n]|\z)+/
 
       module ClassMethods
         def symbol(string)
@@ -78,6 +79,10 @@ def spacing
         skip(SPACING)
       end
 
+      def spacing_without_comment
+        skip(SPACING_WITHOUT_COMMENT)
+      end
+
       def parse_error!(message)
         raise ConfigParseError, "#{message} at #{error_sample}"
       end

lib/fluent/config/element.rb

@@ -102,11 +102,7 @@ def to_s(nest = 0)
           out << "#{indent}<#{@name} #{@arg}>\n"
         end
         each_pair { |k, v|
-          if @v1_config
-            out << "#{nindent}#{k} #{Element.unescape_parameter(v)}\n"
-          else
-            out << "#{nindent}#{k} #{v}\n"
-          end
+          out << "#{nindent}#{k} #{v}\n"
         }
         @elements.each { |e|
           out << e.to_s(nest + 1)

lib/fluent/config/literal_parser.rb

@@ -51,7 +51,7 @@ def initialize(strscan, eval_context)
       end
 
       def parse_literal(string_boundary_charset = LINE_END)
-        spacing
+        spacing_without_comment
 
         value = if skip(/\[/)
                   scan_json(true)
@@ -113,7 +113,9 @@ def scan_nonquoted_string(boundary_charset = LINE_END)
 
         string = []
         while true
-          if s = scan(charset)
+          if s = scan(/\#/)
+            string << '#'
+          elsif s = scan(charset)
             string << s
           else
             break

lib/fluent/config/v1_parser.rb

@@ -100,7 +100,7 @@ def parse_element(root_element, elem_name, attrs = {}, elems = [])
 
           else
             k = scan_string(SPACING)
-            spacing
+            spacing_without_comment
             if prev_match.include?("\n") # support 'tag_mapped' like "without value" configuration
               attrs[k] = ""
             else

spec/config/config_parser_spec.rb

@@ -69,8 +69,31 @@ def e(name, arg='', attrs={}, elements=[])
       expect("k1 a  b  c").to be_parsed_as(e('ROOT', '', {"k1" => "a  b  c"}))
     end
 
-    it "ignores comments after value" do
-      expect("  k1 a#comment").to be_parsed_as(e('ROOT', '', {"k1" => "a"}))
+    context 'non-quoted string' do
+      it "remains text starting with '#'" do
+        expect("  k1 #not_comment").to be_parsed_as(e('ROOT', '', {"k1" => "#not_comment"}))
+      end
+
+      it "remains text just after '#'" do
+        expect("  k1 a#not_comment").to be_parsed_as(e('ROOT', '', {"k1" => "a#not_comment"}))
+      end
+
+      it "remove text after ` #` (comment)" do
+        expect("  k1 a #comment").to be_parsed_as(e('ROOT', '', {"k1" => "a"}))
+      end
+
+      it "does not require escaping backslash" do
+        expect("  k1 \\\\").to be_parsed_as(e('ROOT', '', {"k1" => "\\\\"}))
+        expect("  k1 \\").to be_parsed_as(e('ROOT', '', {"k1" => "\\"}))
+      end
+
+      it "remains backslash in front of a normal character" do
+        expect("  k1 \\[").to be_parsed_as(e('ROOT', '', {"k1" => '\['}))
+      end
+
+      it "does not accept escape characters" do
+        expect("  k1 \\n").to be_parsed_as(e('ROOT', '', {"k1" => '\n'}))
+      end
     end
 
     context 'double quoted string' do
@@ -348,10 +371,10 @@ def prepare_config
     # TODO: Add uri based include spec
   end
 
-  describe 'unescape parameter' do
+  describe '#to_s' do
     it 'parses dumpped configuration' do
-      original = %q!a\\\\\n\r\f\b\\'\\"z!
-      expected = %!a\\\n\r\f\b'"z!
+      original = %q!a\\\n\r\f\b'"z!
+      expected = %q!a\\\n\r\f\b'"z!
 
       conf = parse_text(%[k1 #{original}])
       expect(conf['k1']).to eq(expected) # escape check

spec/config/literal_parser_spec.rb

@@ -131,22 +131,34 @@ def parse_text(text)
   end
 
   describe 'nonquoted string parsing' do
-    # empty
     it { expect('').to be_parsed_as(nil) }
-
-    it { expect('\\"').to be_parsed_as("\\\"") }
-    it { expect('\\t').to be_parsed_as("\\t") }
-    it { expect('\\n').to be_parsed_as("\\n") }
-    it { expect('\\r\\n').to be_parsed_as("\\r\\n") }
-    it { expect('\\f\\b').to be_parsed_as("\\f\\b") }
-    it { expect('\\.t').to be_parsed_as("\\.t") }
-    it { expect('\\$t').to be_parsed_as("\\$t") }
-    it { expect('\\#t').to be_parsed_as("\\") } # comment out
-    it { expect('\\z').to be_parsed_as("\\z") }
-    it { expect('\\0').to be_parsed_as("\\0") }
-    it { expect('\\1').to be_parsed_as("\\1") }
-    it { expect('\\#{test}').to be_parsed_as("\\") } # comment out
-    it { expect('\[').to be_parsed_as("\\[") }
+    it { expect('text').to be_parsed_as('text') }
+    it { expect('\"').to be_parsed_as('\"') }
+    it { expect('\t').to be_parsed_as('\t') }
+    it { expect('\n').to be_parsed_as('\n') }
+    it { expect('\r\n').to be_parsed_as('\r\n') }
+    it { expect('\f\b').to be_parsed_as('\f\b') }
+    it { expect('\.t').to be_parsed_as('\.t') }
+    it { expect('\$t').to be_parsed_as('\$t') }
+    it { expect('\#t').to be_parsed_as('\#t') }
+    it { expect('\z').to be_parsed_as('\z') }
+    it { expect('\0').to be_parsed_as('\0') }
+    it { expect('\1').to be_parsed_as('\1') }
+    it { expect('.').to be_parsed_as('.') }
+    it { expect('*').to be_parsed_as('*') }
+    it { expect('@').to be_parsed_as('@') }
+    it { expect('#{test}').to be_parsed_as('#{test}') }
+    it { expect('$').to be_parsed_as('$') }
+    it { expect('$t').to be_parsed_as('$t') }
+    it { expect('$}').to be_parsed_as('$}') }
+    it { expect('\\\\').to be_parsed_as('\\\\') }
+    it { expect('\[').to be_parsed_as('\[') }
+    it { expect('#foo').to be_parsed_as('#foo') } # not comment out
+    it { expect('foo#bar').to be_parsed_as('foo#bar') } # not comment out
+    it { expect(' text').to be_parsed_as('text') } # remove starting spaces
+    it { expect(' #foo').to be_parsed_as('#foo') } # remove starting spaces
+    it { expect('foo #bar').to be_parsed_as('foo') } # comment out
+    it { expect("foo\t#bar").to be_parsed_as('foo') } # comment out
 
     it { expect('t').to be_parsed_as('t') }
     it { expect('T').to be_parsed_as('T') }

test/plugin/test_in_http.rb

@@ -157,7 +157,7 @@ def test_multi_msgpack
 
   def test_with_regexp
     d = create_driver(CONFIG + %[
-      format /^(?<field_1>\\\\d+):(?<field_2>\\\\w+)$/
+      format /^(?<field_1>\\d+):(?<field_2>\\w+)$/
       types field_1:integer
     ])