show-trailing-whitespace does not work with.

[srphcr]

(setq-default show-trailing-whitespace t)

This setting does not work with php-mode.

I use

GNU Emacs 24.3.1 (x86_64-apple-darwin13.1.0)

[brkalmar]

Different coding styles handle trailing whitespace differently; Drupal style is the only one which sets show-trailing-whitespace to t, regardless of the variable's previous value. I'm assuming that you use a different coding style.

A solution to your problem would be customizing php-mode-coding-style to use Drupal coding style, which always shows trailing whitespaces.

[syohex]

php-mode should set user default value instead of nil other than Drupal.

[syohex]

@Seraphicer php-mode uses user default value of show-trailing-whitespace except
Drupal style. Please check latest version and reopen if you still have problem.