However, error messages like this don't help much:
Parse error: syntax error, unexpected T_SL in /usr/local/apache2/htdocs/proj/include/file.php on line 703
That's supposed to tell me that there's probably an extra space after my declaration of a tag for a heredoc:
$foo = <<<END_FOO[ space ]
T_SLstands for the Token Shift-Left operator. At least it's not too hard to search for these messages.
I know that it's possible that this error could arise due to a condition unrelated to heredocs. However, I'm a big advocate of providing extra support for the common case. If you want to take this to an extreme, you can do a study on the various causes of an error that might produce a given message. Then you provide extra context or help text for the most common case(s). I know there's a (DWIM, QWAN, TMTOWTDI, DRY)-style acronym out there somewhere for this principle, but it escapes me at the moment.