Reserve future support for comment line before a tag name

lib/liquid/locales/en.yml

@@ -22,6 +22,7 @@
       tag_never_closed: "'%{block_name}' tag was never closed"
       table_row: "Syntax Error in 'table_row loop' - Valid syntax: table_row [item] in [collection] cols=3"
       render: "Syntax error in tag 'render' - Template name must be a quoted string"
+      inline_comment_invalid: "Syntax error in tag '#' - Each line of comments must be prefixed by the '#' character"
     argument:
       include: "Argument error in tag 'include' - Illegal template name"
     disabled:

lib/liquid/tags/inline_comment.rb

@@ -2,6 +2,16 @@
 
 module Liquid
   class InlineComment < Tag
+    def initialize(tag_name, markup, options)
+      super
+      # Semantically, a comment should only ignore everything after it on the line.
+      # Currently, this implementation doesn't support mixing a comment with another tag
+      # but we need to reserve future support for this.
+      if markup.match?(/\n\s*[^#]/)
+        raise SyntaxError, options[:locale].t("errors.syntax.inline_comment_invalid")
+      end
+    end
+
     def render_to_output_buffer(_context, output)
       output
     end

test/integration/tags/inline_comment_test.rb

@@ -26,7 +26,9 @@ class InlineCommentTest < Minitest::Test
 
   def test_comment_inline_tag
     assert_template_result('ok', '{% echo "ok" # output something from a tag %}')
+  end
 
+  def test_comment_line_before_tag
     assert_template_result('ok', '{% # this sort of comment also
       echo "ok" %}')
   end