SRFI-19: Add support for ISO 8601 zones with a colon.

* module/srfi/srfi-19.scm (zone-reader): handle a colon in the zone.

* test-suite/tests/srfi-19.test (SRFI date/time library test): Add test.

Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo@cyberdimension.org>

[rlb@defaultvalue.org: adjust commit message; add NEWS]

NEWS

@@ -54,6 +54,7 @@ This speeds up copying large files a lot while saving the disk space.
    (<https://bugs.gnu.org/55344>)
 ** 'make-custom-port' now honors its #:conversion-strategy argument
 ** 'eval-string' respects #:column (previously it was set to the #:line)
+** 'string->date' now allows a colon in the ISO 8601 zone offset
 ** Hashing of UTF-8 symbols with non-ASCII characters avoids corruption
    (<https://bugs.gnu.org/56413>)
 

module/srfi/srfi-19.scm

@@ -1268,6 +1268,8 @@
               (set! offset (+ offset (* (char->int ch)
                                         60 60))))
             (let ((ch (read-char port)))
+              (if (eqv? ch #\:)
+                  (set! ch (read-char port)))
               (if (eof-object? ch)
                   (time-error 'string->date 'bad-date-template-string
                               (list "Invalid time zone number" ch)))

test-suite/tests/srfi-19.test

@@ -120,6 +120,9 @@ incomplete numerical tower implementation.)"
   (pass-if "string->date works"
 	   (begin (string->date "2001-06-01@14:00" "~Y-~m-~d@~H:~M")
 		  #t))
+  (pass-if "string->date accepts ISO 8601 zones with a colon"
+	   (begin (string->date "2024-12-31T23:59:59+01:00" "~Y-~m-~dT~H:~M:~S~z")
+		  #t))
   ;; check for code paths where reals were passed to quotient, which
   ;; doesn't work in Guile (and is unspecified in R5RS)
   (test-time->date time-utc->date date->time-utc)