Description:
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I stumbled about this issue while debugging a project which uses PEAR XML_Parser which relys on the assumption that strtoupper() works for all US-ASCII characters no matter which locale or encoding.

Unfortunately, it does not.
This has been discussed in PHP bugs
22003
21771
35583

The letter i isn't converted to I by strtoupper() when the locale is set to turkish (via setlocale(LC_ALL, 'tr_TR'))
However, the letter i is converted to I by strtoupper() when the locale is set to turkish (via setlocale(LC_ALL, 'tr'))
mb_strtoupper() does work under all encodings.

Now, despite blaming the Unicode guys or the turkish language or whatever:

How are we supposed to code properly under these circumstances?

My proposal:
strtoupper/lower() claim to be locale aware, but they really aren't (try to upperchase umlaut ??? under locale de_DE - doesn't work at all). Thus, redefining these functions to work for 7-bit encoded (US-ASCII) data _only_ won't change anything. Skip the locale dependency, then the locale tr_TR will work.


Reproduce code:
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jo@l33t ~> php -r 'setlocale(LC_ALL, "tr"); $text = "begin"; printf("%s %s\n", strtoupper($text), bin2hex(strtoupper($text))); '
BEGIN 424547494e
jo@l33t ~> php -r 'setlocale(LC_ALL, "tr_TR"); $text = "begin"; printf("%s %s\n", strtoupper($text), bin2hex(strtoupper($text))); '
BEG�N 424547dd4e
jo@l33t ~> php -r 'setlocale(LC_ALL, "tr_TR.UTF-8"); $text = "begin"; printf("%s %s\n", strtoupper($text), bin2hex(strtoupper($text))); '
BEGiN 424547694e


Expected result:
----------------
BEGIN 424547494e
(for all locales)

Actual result:
--------------
(see above)