Make '- end' an error in Haml with a useful error message.

lib/haml/precompiler.rb

@@ -197,6 +197,14 @@ END
       when SILENT_SCRIPT
         return start_haml_comment if text[1] == SILENT_COMMENT
 
+        raise SyntaxError.new(<<END.rstrip, index) if text[1..-1].strip == "end"
+You don't need to use "- end" in Haml. Use indentation instead:
+- if foo?
+  %strong Foo!
+- else
+  Not foo.
+END
+
         push_silent(text[1..-1], true)
         newline_now
         if (@block_opened && !mid_block_keyword?(text)) || text[1..-1].split(' ', 2)[0] == "case"

test/haml/engine_test.rb

@@ -34,6 +34,13 @@ END
     "%a/ b" => "Self-closing tags can't have content.",
     " %p foo" => "Indenting at the beginning of the document is illegal.",
     "  %p foo" => "Indenting at the beginning of the document is illegal.",
+    "- end" => <<END.rstrip,
+You don't need to use "- end" in Haml. Use indentation instead:
+- if foo?
+  %strong Foo!
+- else
+  Not foo.
+END
     " \n\t\n %p foo" => ["Indenting at the beginning of the document is illegal.", 3],
 
     # Regression tests