source::encoding -- Declare Perl source code encoding
use source::encoding 'ascii';
use source::encoding 'utf8';
no source::encoding;These days, Perl code either generally contains only ASCII characters with \x{} and similar escapes to represent non-ASCII, or use utf8 is used to indicate that the source code itself contains characters encoded as UTF-8.
That means that a character in the source code not meeting these criteria is often a typographical error. This pragma is used to tell Perl to raise an error when this happens.
use source::encoding 'utf8' is a synonym for use utf8. They may be used interchangeably.
use source::encoding 'ascii' turns off any UTF-8 expectations, and raises a fatal error if any character within its scope in the input source code is not ASCII (or ASCII-equivalent on EBCDIC systems).
no source::encoding turns off any UTF-8/ASCII expectations for the remainder of its scope. The meaning of non-ASCII characters is then undefined.
use source::encoding 'ascii' is automatically enabled within the lexical scope of a use v5.41.0 or higher.