Hi, I've run the script

<?php
  echo '\'a\' . \'b\' = ' . ('a' . 'b') . '<br>';
  echo '\'a\' + \'b\' = ' . ('a' + 'b') . '<br>';  // !WARN!
  echo '"a" . "b" = ' . ("a" . "b") . '<br>';
  echo '"a" + "b" = ' . ("a" + "b") . '<br>';      // !WARN!
  echo 'a . b = ' . (a . b) . '<br>';
  echo 'a + b = ' . (a + b) . '<br>';              // !WARN!

  echo '\'1\' . \'2\' = ' . ('1' . '2') . '<br>';
  echo '\'1\' + \'2\' = ' . ('1' + '2') . '<br>';  // !WARN!
  echo '"1" . "2" = ' . ("1" . "2") . '<br>';
  echo '"1" + "2" = ' . ("1" + "2") . '<br>';      // !WARN!
  echo '1 . 2 = ' . (1 . 2) . '<br>';
  echo '1 + 2 = ' . (1 + 2) . '<br>';

  echo '\'5\' . \'k\' = ' . ('5' . 'k') . '<br>';
  echo '\'5\' + \'k\' = ' . ('5' + 'k') . '<br>';  // !WARN!
  echo '"5" . "k" = ' . ("5" . "k") . '<br>';
  echo '"5" + "k" = ' . ("5" + "k") . '<br>';      // !WARN!
  echo '5 . k = ' . (5 . k) . '<br>';
  echo '5 + k = ' . (5 + k) . '<br>';              // !WARN!
?>

with "warn_plus_overloading = On" expecting to generate some warnings (on lines with // !WARN!), however nothing ever got reported (except the use of undefined constants).

Am I misinterpreting the "warn_plus_overloading" function?
in PHP.INI I have
  error_reporting       = E_ALL
  display_errors        = On     ; will set to Off soon
  log_errors            = On
  error_log             = C:/WebSite/phperror.log
  track_errors          = Off
  warn_plus_overloading = On     ; tested with Off too