C:\>perl
#!perl -C --
Unknown Unicode option letter ' ' at - line 1.

C:\>perl
#perl -C2 --
print chr 333;
^Z
Wide character in print at - line 2.
ō

C:\>perl -C2 -e"print chr 333;"
ō
[download]

No, -T is doing its job.

No, it's not. The message you got is not a warning, the program terminates after that. Save this as foo.pl:

#!perl -T
print 42;
[download]

then run it:

C:\Users\burak\Desktop>perl foo.pl
"-T" is on the #! line, it must also be used on the command line at fo
+o.pl line 1.

C:\Users\burak\Desktop>
[download]

try again with -T on the commandline:

C:\Users\burak\Desktop>perl -T foo.pl
42
C:\Users\burak\Desktop>
[download]