Description:
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This was actually found on 5.2.8, the current main PHP release (not sure why it's not listed in the PHP version dropdown on the bug report page... ??)

The problem is this: I'm importing a number of PHP files with require_once() into a main page but I get a blank page. I debugged it down to two lines of code in one of the files file that is being included. These two lines are inside a function that is NOT called, however.

  if (!$something)
    ft_handle_error("one" . "two" . "three", mysql_error());

When I comment these two lines out, the page loads fine. No errors, notifications or warnings are displayed. When I remove one (any) of the strings being concatenated in the first function parameter, the page loads fine. In other words, when I change the lines to any of these, the page loads fine:

  if (!$something)
    ft_handle_error("two" . "three", mysql_error());

As does:

  if (!$something)
    ft_handle_error("one" . "three", mysql_error());

As does:

  if (!$something)
    ft_handle_error("one" . "two", mysql_error());

Two final things to mention: when I remove the second mysql_error() parameter but keep all three strings being concatenated in the first parameter, the page loads. Also, when I remove the if (!$something) condition and keep all three strings being concatenated again, it also works fine. The actual strings being concatenated don't seem to make any difference.

I'm well beyond confused. Debugging tips?

Reproduce code:
---------------
  if (!$something)
    ft_handle_error("one" . "two" . "three", mysql_error());


Expected result:
----------------
The page should load for ANY of the lines of PHP code mentioned.