php root namespace functions list

#php

Below is a list of functions in php which benefit from being prefixed with a root namespace, for example \in_array()

array_slice
assert
boolval
call_user_func
call_user_func_array
chr
count
defined
doubleval
floatval
func_get_args
func_num_args
get_called_class
get_class
gettype
in_array
intval
is_array
is_bool
is_double
is_float
is_int
is_integer
is_long
is_null
is_object
is_real
is_resource
is_string
ord
strlen
strval

Source:
https://github.com/php/php-src/blob/f2db305fa4e9bd7d04d567822687ec714aedcdb5/Zend/zend_compile.c#L3872