date: fix UTC keyword with relative seconds across DST (#12555)

Cargo.toml

@@ -437,7 +437,7 @@ num-bigint = "0.4.4"
 num-prime = "0.5.0"
 num-traits = "0.2.19"
 onig = { version = "~6.5.1", default-features = false }
-parse_datetime = "0.14.0"
+parse_datetime = "0.15.0"
 phf = "0.13.1"
 phf_codegen = "0.13.1"
 platform-info = "2.0.3"
@@ -769,3 +769,6 @@ debug = true
 
 [lints]
 workspace = true
+
+[patch.crates-io]
+parse_datetime = { path = "../parse_datetime" }

src/uu/date/src/date.rs

@@ -854,7 +854,10 @@ fn try_parse_with_abbreviation<S: AsRef<str>>(date_str: S, now: &Zoned) -> Optio
             if let Some(tz) = tz {
                 let date_part = s.trim_end_matches(last_word).trim();
                 // Parse in the target timezone so "10:30 EDT" means 10:30 in EDT.
-                if let Ok(parsed) = parse_datetime::parse_datetime_at_date(now.clone(), date_part) {
+                if let Some(parsed) = parse_datetime::parse_datetime_at_date(now.clone(), date_part)
+                    .ok()
+                    .and_then(|p| p.into_zoned())
+                {
                     let dt = parsed.datetime();
                     if let Ok(zoned) = dt.to_zoned(tz) {
                         // The trailing abbreviation only describes the *input*
@@ -932,9 +935,17 @@ fn parse_date<S: AsRef<str> + Clone>(
     }
 
     match parse_datetime::parse_datetime_at_date(now.clone(), input_str) {
-        // Convert to system timezone for display
-        // (parse_datetime 0.13 returns Zoned in the input's timezone)
-        Ok(date) => {
+        // Convert to system timezone for display.
+        // parse_datetime returns the value in the input's timezone; the
+        // `Extended` variant covers years outside jiff's range, which `date`
+        // cannot represent, so treat it as an invalid input.
+        Ok(parsed) => {
+            let Some(date) = parsed.into_zoned() else {
+                return Err((
+                    input_str.into(),
+                    parse_datetime::ParseDateTimeError::InvalidInput,
+                ));
+            };
             let result = date.timestamp().to_zoned(now.time_zone().clone());
             if dbg_opts.debug {
                 // Show final parsed date and time

src/uu/touch/src/touch.rs

@@ -714,7 +714,10 @@ fn parse_date(ref_zoned: Zoned, s: &str) -> Result<FileTime, TouchError> {
         }
     }
 
-    if let Ok(zoned) = parse_datetime::parse_datetime_at_date(ref_zoned, s) {
+    if let Some(zoned) = parse_datetime::parse_datetime_at_date(ref_zoned, s)
+        .ok()
+        .and_then(|parsed| parsed.into_zoned())
+    {
         return Ok(timestamp_to_filetime(zoned.timestamp()));
     }
 

tests/by-util/test_date.rs

@@ -316,6 +316,21 @@ fn test_date_utc_vs_local() {
     }
 }
 
+#[test]
+fn test_date_utc_keyword_plus_relative_seconds_across_dst() {
+    // Regression test for #12555. The "UTC" keyword fixes the offset and must
+    // anchor the instant before the relative "N seconds" is applied. In a
+    // DST-observing zone, the epoch base is in winter (CET, +1) while the result
+    // lands in summer (CEST, +2); a naive implementation drifts by one hour.
+    // "1970-01-01 UTC + N seconds" must always be exactly N seconds past the epoch.
+    let seconds = 1_780_318_971; // lands in summer 2026
+    new_ucmd!()
+        .env("TZ", "Europe/Berlin")
+        .args(&["-d", &format!("1970/01/01 UTC {seconds} seconds"), "+%s"])
+        .succeeds()
+        .stdout_only(format!("{seconds}\n"));
+}
+
 #[test]
 fn test_date_utc_output_formats() {
     let cases = [