From e55e7d304b91c0777a13bbd6d861c033f6ccb583 Mon Sep 17 00:00:00 2001
From: daxpedda <daxpedda@gmail.com>
Date: Mon, 9 Dec 2024 12:26:25 +0100
Subject: [PATCH] Track upstream `Instant` and `SystemTime` sources

---
 .github/upstream-sources.json |  7 +++++++
 src/time/instant.rs           |  2 ++
 src/time/system_time.rs       | 12 ++++++------
 3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/.github/upstream-sources.json b/.github/upstream-sources.json
index 7fc664e..b5abe53 100644
--- a/.github/upstream-sources.json
+++ b/.github/upstream-sources.json
@@ -3,6 +3,13 @@
 	{ "owner": "rust-lang", "repo": "libm", "tag": "libm-v0.2.11", "path": "src/math/copysign.rs" },
 	{ "owner": "rust-lang", "repo": "libm", "tag": "libm-v0.2.11", "path": "src/math/round.rs" },
 	{ "owner": "rust-lang", "repo": "rust", "tag": "1.83.0", "path": "library/core/src/time.rs" },
+	{ "owner": "rust-lang", "repo": "rust", "tag": "1.83.0", "path": "library/std/src/time.rs" },
+	{
+		"owner": "rust-lang",
+		"repo": "rust",
+		"tag": "1.83.0",
+		"path": "library/std/src/sys/pal/unsupported/time.rs"
+	},
 	{
 		"owner": "rust-lang",
 		"repo": "rust",
diff --git a/src/time/instant.rs b/src/time/instant.rs
index 2411261..715c3cf 100644
--- a/src/time/instant.rs
+++ b/src/time/instant.rs
@@ -1,4 +1,6 @@
 //! Re-implementation of [`std::time::Instant`].
+//!
+//! See <https://github.com/rust-lang/rust/blob/1.83.0/library/std/src/time.rs#L271-L468>.
 #![cfg_attr(
 	not(feature = "std"),
 	doc = "",
diff --git a/src/time/system_time.rs b/src/time/system_time.rs
index 866277f..f6a0e8c 100644
--- a/src/time/system_time.rs
+++ b/src/time/system_time.rs
@@ -1,5 +1,6 @@
 //! Re-implementation of [`std::time::SystemTime`].
-
+//!
+//! See <https://github.com/rust-lang/rust/blob/1.83.0/library/std/src/time.rs#L470-L707>.
 #![cfg_attr(
 	not(feature = "std"),
 	doc = "",
@@ -56,11 +57,10 @@ impl SystemTime {
 	)]
 	#[allow(clippy::missing_errors_doc, clippy::trivially_copy_pass_by_ref)]
 	pub fn duration_since(&self, earlier: Self) -> Result<Duration, SystemTimeError> {
-		if self.0 < earlier.0 {
-			Err(SystemTimeError(earlier.0 - self.0))
-		} else {
-			Ok(self.0 - earlier.0)
-		}
+		// See <https://github.com/rust-lang/rust/blob/1.83.0/library/std/src/sys/pal/unsupported/time.rs#L34-L36>.
+		self.0
+			.checked_sub(earlier.0)
+			.ok_or_else(|| SystemTimeError(earlier.0 - self.0))
 	}
 
 	/// See [`std::time::SystemTime::elapsed()`].