Fix #309

This simple change fixes all reported invalid values.

CHANGELOG.md

@@ -7,6 +7,12 @@ Versioning].
 
 ---
 
+## 0.2.25 [2021-01-24]
+
+### Fixed
+
+- Fix #309, which can cause panics in certain situations.
+
 ## 0.2.24 [2021-01-08]
 
 ### Fixed

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "time"
-version = "0.2.24"
+version = "0.2.25"
 authors = ["Jacob Pratt <the.z.cuber@gmail.com>"]
 edition = "2018"
 repository = "https://github.com/time-rs/time"

src/date.rs

@@ -542,11 +542,11 @@ impl Date {
         };
 
         let raw_weekday =
-            (day as i32 + (13 * (month as i32 + 1)) / 5 + adjusted_year + adjusted_year / 4
+            ((day as i32 + (13 * (month as i32 + 1)) / 5 + adjusted_year + adjusted_year / 4
                 - adjusted_year / 100
                 + adjusted_year / 400)
-                % 7
-                - 2;
+                - 2)
+                % 7;
 
         if raw_weekday < 0 {
             (raw_weekday + 7) as u8
@@ -586,7 +586,7 @@ impl Date {
             6 => Weekday::Sunday,
             // FIXME The compiler isn't able to optimize this away. See
             // rust-lang/rust#66993.
-            _ => unreachable!("A value mod 7 is always in the range 0..7"),
+            n => unreachable!("A value mod 7 is always in the range 0..7 (was {})", n),
         }
     }
 

tests/date.rs

@@ -1230,3 +1230,14 @@ fn previous_day_panics() {
 fn julian_day_panics() {
     Date::from_julian_day(i64::MAX);
 }
+
+#[test]
+fn issue_309() {
+    assert_eq!(date!(-36 - 11 - 01).weekday(), Weekday::Sunday);
+    assert_eq!(date!(-26 - 96).weekday(), Weekday::Sunday);
+    assert_eq!(date!(-31 - 137).weekday(), Weekday::Sunday);
+    assert_eq!(date!(-31 - 137).week(), 20);
+    assert_eq!(date!(-60 - 63).iso_year_week(), (-60, 9));
+    assert_eq!(date!(-208 - 99).week(), 14);
+    assert_eq!(util::weeks_in_year(-102), 52);
+}