date input: unrecognized trailing tokens rejected (e.g. `8j`, `8 j`)

[sylvestre]

Summary

GNU date silently ignores unrecognized trailing word-tokens and parses the preceding number as an hour. parse_datetime errors out instead.

Found by a fuzz_date run on uutils/coreutils.

Reproduction

$ TZ=UTC /usr/bin/date -u -d '8j' '+%H:%M:%S'
08:00:00
$ echo $?
0

$ TZ=UTC target/debug/coreutils date -u -d '8j' '+%H:%M:%S'
date: invalid date '8j'
$ echo $?
1

$ TZ=UTC /usr/bin/date -u -d '8 j' '+%H:%M:%S'
08:00:00

$ TZ=UTC target/debug/coreutils date -u -d '8 j' '+%H:%M:%S'
date: invalid date '8 j'

Test (in uutils/coreutils integration suite)

#[test]
fn test_date_ignores_unrecognized_trailing_tokens() {
    for input in ["8j", "8 j"] {
        new_ucmd!()
            .env("TZ", "UTC")
            .arg("-u")
            .arg("-d")
            .arg(input)
            .arg("+%H:%M:%S")
            .succeeds()
            .stdout_only("08:00:00\n");
    }
}