[PATCH v2] SRFI-19: Add support for ISO 8601 zones with a colon.

[Denis 'GNUtoo' Carikli <GNUtoo@cyberdimension.org>]

* 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>
---
ChangeLog v1->v2:
- Improved error message to be more meaningful.
- Removed duplicated code: in the v1, the read, oef-object test, and
  error messages were duplicated.
---
 module/srfi/srfi-19.scm       | 16 ++++++++++------
 test-suite/tests/srfi-19.test |  3 +++
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/module/srfi/srfi-19.scm b/module/srfi/srfi-19.scm
index 570f933ca..ad1867506 100644
--- a/module/srfi/srfi-19.scm
+++ b/module/srfi/srfi-19.scm
@@ -1267,12 +1267,16 @@
                               (list "Invalid time zone number" ch)))
               (set! offset (+ offset (* (char->int ch)
                                         60 60))))
-            (let ((ch (read-char port)))
-              (if (eof-object? ch)
-                  (time-error 'string->date 'bad-date-template-string
-                              (list "Invalid time zone number" ch)))
-              (set! offset (+ offset (* (char->int ch)
-                                        10 60))))
+            (let ((f (lambda ()
+                       (let ((ch (read-char port)))
+                         (if (eof-object? ch)
+                             (time-error
+                              'string->date 'bad-date-template-string
+                              (list "Missing required time zone minutes" ch))
+                             ch)))))
+              (let ((ch (f)))
+                (if (char=? ch #\:) (set! ch (f)))
+                (set! offset (+ offset (* (char->int ch) 10 60)))))
             (let ((ch (read-char port)))
               (if (eof-object? ch)
                   (time-error 'string->date 'bad-date-template-string
diff --git a/test-suite/tests/srfi-19.test b/test-suite/tests/srfi-19.test
index 1d56214e4..55eb82320 100644
--- a/test-suite/tests/srfi-19.test
+++ b/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)

base-commit: 54c4753dd3f7506bee2778b36d7263b613ffd579
-- 
2.41.0