error_reporting(E_ALL) does not produce error

Question

This is my php script-

 \' ;. $thisdoesnotexist);
?>

Which obviously should

Answer 1

That error is a parse error. The parser is throwing it while going through the code, trying to understand it. No code is being executed yet in the parsing stage. Because of that it hasn't yet executed the error_reporting line, therefore the error reporting settings aren't changed yet.

You cannot change error reporting settings (or really, do anything) in a file with syntax errors.