HHVM's default locale is C; PHP selects it based on user environment

[atdt]

 $ hhvm --php -r "var_dump(fnmatch('foob?r', 'foobér'));"
  bool(false)
  $ php5 -r "var_dump(fnmatch('foob?r', 'foobér'));"
  bool(true)

This is because:

$ hhvm --php -r 'var_dump(setlocale(LC_ALL,0));'
string(1) "C"
$ php5 -r 'var_dump(setlocale(LC_ALL,0));'
string(170) "LC_CTYPE=en_US.UTF-8;LC_NUMERIC=C;LC_TIME=C;LC_COLLATE=C;LC_MONETARY=C;LC_MESSAGES=C;LC_PAPER=C;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=C;LC_IDENTIFICATION=C"

PHP calls setlocale(LC_CTYPE, "") on initialization, but HHVM sticks to the POSIX/C locale.

[fredemmott]

Low pri because it's best practice to explicitly set it anyway to avoid issues where your production environment and development environment differ.