#highlight_failed now accepts tag name, and proper syntax

plugins/backtick_code_block.rb

@@ -41,7 +41,7 @@ module BacktickCodeBlock
         begin
           highlight(code, @options)
         rescue
-          highlight_failed(nil, code, @options[:lang])
+          highlight_failed('backtick_code_block', "``` [lang]\n              code\n              ```", code, @options[:lang])
         end
       end
     end

plugins/code_block.rb

@@ -85,7 +85,7 @@ module Jekyll
         code = code + context['pygments_suffix'] if context['pygments_suffix']
         code
       rescue
-        highlight_failed(nil, code, @options[:lang])
+        highlight_failed('code_block', 'codeblock [title] [url] [link text]', code, @options[:lang])
       end
     end
   end

plugins/gist_tag.rb

@@ -56,7 +56,7 @@ module Jekyll
           begin
             code = highlight(code, @options)
           rescue
-            highlight_failed(file, code, @options[:lang])
+            highlight_failed('gist', 'gist gist_id [filename]', code, @options[:lang], file)
           end
         end
         code || cache

plugins/include_code.rb

@@ -88,7 +88,7 @@ module Jekyll
         begin
           highlight(code, @options)
         rescue
-          highlight_failed(@file, code, @options[:lang])
+          highlight_failed('include_code', 'include_code path/to/file [title]', code, @options[:lang], filepath)
         end
       end
     end

plugins/pygments_code.rb

@@ -184,13 +184,18 @@ module HighlightCode
     code
   end
 
-  def highlight_failed(file, code, lang)
-    code_snippet = code.split("\n")[0..9].map{|l| ">> #{l}" }.join("\n")
-    fail_message =  "Pygments doesn't know how to highlight your code in lang '#{lang}'."
-    fail_message += "\nFailing code from #{file}:" if file
-    fail_message += "\n\n#{code_snippet}"
-    fail_message += "\n>> ..." if code.split("\n").size > 10
-    $stderr.puts fail_message.red
+  def highlight_failed(tag, syntax, code, lang, file = nil)
+    code_snippet = code.split("\n")[0..9].map{|l| "    #{l}" }.join("\n")
+    fail_message = <<-MESSAGE
+Syntax Error in tag '#{tag}' while parsing the following markup in lang '#{lang}':
+#{"(Failing code from #{file})" if file}
+
+#{code_snippet}
+#{"    ..." if code.split("\n").size > 10}
+
+Valid syntax: #{syntax}
+MESSAGE
+    $stderr.puts fail_message.chomp.red
     raise ArgumentError
   end
 

source/downloads/code/lolz.fsh

@@ -0,0 +1 @@
+Hi hi hi lolz