23:15 >perl -wE "my $r = qr{(?:a|b)}; say $r;"
(?^u:(?:a|b))

23:17 >perl -wE "my $r = qr{(?:a|b){1}}; say $r;"
(?^u:(?:a|b){1})

23:17 >perl -wE "my $r = qr{(?:a|b){1}+}; say $r;"
Useless use of greediness modifier '+' in regex; marked by <-- HERE in m/(?:a|b){1}+ <-- HERE / at -e line 1.
(?^u:(?:a|b){1}+)

23:17 >perl -v

This is perl 5, version 22, subversion 0 (v5.22.0) built for MSWin32-x64-multi-thread
...