Repro duration_since regression from issue 146228

Author: stepancheg

library/std/src/sys/pal/hermit/time.rs

@@ -29,12 +29,12 @@ impl Timespec {
         if self >= other {
             Ok(if self.t.tv_nsec >= other.t.tv_nsec {
                 Duration::new(
-                    (self.t.tv_sec - other.t.tv_sec) as u64,
+                    self.t.tv_sec.wrapping_sub(other.t.tv_sec) as u64,
                     (self.t.tv_nsec - other.t.tv_nsec) as u32,
                 )
             } else {
                 Duration::new(
-                    (self.t.tv_sec - 1 - other.t.tv_sec) as u64,
+                    (self.t.tv_sec - 1).wrapping_sub(other.t.tv_sec) as u64,
                     (self.t.tv_nsec + NSEC_PER_SEC - other.t.tv_nsec) as u32,
                 )
             })

library/std/src/sys/pal/unix/time.rs

@@ -150,12 +150,12 @@ impl Timespec {
             // directly expresses the lower-cost behavior we want from it.
             let (secs, nsec) = if self.tv_nsec.as_inner() >= other.tv_nsec.as_inner() {
                 (
-                    (self.tv_sec - other.tv_sec) as u64,
+                    self.tv_sec.wrapping_sub(other.tv_sec) as u64,
                     self.tv_nsec.as_inner() - other.tv_nsec.as_inner(),
                 )
             } else {
                 (
-                    (self.tv_sec - other.tv_sec - 1) as u64,
+                    (self.tv_sec - 1).wrapping_sub(other.tv_sec) as u64,
                     self.tv_nsec.as_inner() + (NSEC_PER_SEC as u32) - other.tv_nsec.as_inner(),
                 )
             };

library/std/tests/time.rs

@@ -227,3 +227,19 @@ fn big_math() {
     check(instant.checked_add(Duration::from_secs(100)), Instant::checked_sub);
     check(instant.checked_add(Duration::from_secs(i64::MAX as _)), Instant::checked_sub);
 }
+
+#[test]
+#[cfg(unix)]
+fn system_time_duration_since_max_range_on_unix() {
+    // Repro regression https://github.com/rust-lang/rust/issues/146228
+
+    // Min and max values of `SystemTime` on Unix.
+    let min = SystemTime::UNIX_EPOCH - (Duration::new(i64::MAX as u64 + 1, 0));
+    let max = SystemTime::UNIX_EPOCH + (Duration::new(i64::MAX as u64, 999_999_999));
+
+    let delta_a = max.duration_since(min).expect("duration_since overflow");
+    let delta_b = min.duration_since(max).err().expect("duration_since overflow").duration();
+
+    assert_eq!(Duration::MAX, delta_a);
+    assert_eq!(Duration::MAX, delta_b);
+}