From a0e2a7f919a6a5eef3d40d38baaec91b852a1940 Mon Sep 17 00:00:00 2001
From: A2 <a2line@gmail.com>
Date: Fri, 6 Feb 2026 15:45:15 +0100
Subject: [PATCH] reject year 0 for Hebrew, French and Islamic calendars

These calendars have no year zero. Previously, year=0 passed
validation and produced incorrect conversions (e.g. Hebrew
d=0,m=0,y=0 mapped to d=1,m=1,y=2). Add check_year year>0
for all three calendar kinds in make.

Fixes geneweb/geneweb#160
---
 lib/calendars.ml | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/calendars.ml b/lib/calendars.ml
index b8a0b95..8043451 100644
--- a/lib/calendars.ml
+++ b/lib/calendars.ml
@@ -553,12 +553,15 @@ let make :
           ~error:(Fun.const @@ check_greg ())
           (check_year (fun () -> year < -45))
     | Hebrew ->
+        check_year (fun () -> year > 0) >>= fun () ->
         check_month (fun () -> month <= 13) >>= fun () ->
         check_day (fun () -> day <= hebrew_nb_days_upper_bound.(month - 1))
     | French ->
+        check_year (fun () -> year > 0) >>= fun () ->
         check_month (fun () -> month <= 13) >>= fun () ->
         check_day (fun () -> day <= 30)
     | Islamic ->
+        check_year (fun () -> year > 0) >>= fun () ->
         check_month (fun () -> month <= 12) >>= fun () ->
         check_day (fun () -> day <= 30)
   in