Fix decode-time/encode-time roundtrip on macOS

* src/timefns.c (Fencode_time): Ignore DST flag when the zone is
numeric or is a cons, as the doc string says it’s ignored in that
case, and not ignoring it causes encode-time to not invert
decode-time on some platforms (Bug#35502).
* test/src/timefns-tests.el (encode-time-dst-numeric-zone):
New test.

1 files changed, 6 insertions, 0 deletions

diff --git a/test/src/timefns-tests.el b/test/src/timefns-tests.el
index 5c858ef3bd8..2c90af757f0 100644
--- a/test/src/timefns-tests.el
+++ b/test/src/timefns-tests.el
@@ -142,3 +142,9 @@
                       (< 0.99 (/ x y) 1.01)
                       (< 0.99 (/ (- (float-time a)) (float-time b))
                          1.01))))))))
+
+(ert-deftest encode-time-dst-numeric-zone ()
+    "Check for Bug#35502."
+    (should (time-equal-p
+             (encode-time '(29 31 17 30 4 2019 2 t 7200))
+             '(23752 27217))))