Fixes <https://bugs.gnu.org/21906>.
Mitigates <https://bugs.gnu.org/21903> and <https://bugs.gnu.org/21904>.
Reported by: Zefram <zefram@fysh.org>.
* module/srfi/srfi-19.scm (encode-julian-day-number)
(decode-julian-day-number, date-week-number): Use 'floor-quotient'
instead of 'quotient', and 'floor' instead of 'truncate', where
appropriate.
(time-utc->date): Ensure that the 'nanoseconds' field of the returned
date is non-negative.
(leap-year): Handle negative years properly, and reformulate the
computation.
(week-day): Handle negative years properly. Use 'floor-quotient'
instead of 'quotient' where appropriate.
(directives): In the handler for '~Y' format escapes, improve the
handling of years outside of the range 0-9999.
(read-directives): Add a FIXME comment to fix the '~Y' reader to handle
years outside of the range 0-9999.
* test-suite/tests/srfi-19.test: Import (srfi srfi-1). Use Guile's
modern keyword notation in the 'define-module' form. Add more tests.
a58c7abd72