Convert FixedOffset::{east, west} to return Result

Author: pitdicker

src/format/parsed.rs

@@ -926,7 +926,7 @@ impl Parsed {
     /// - `OUT_OF_RANGE` if the offset is out of range for a `FixedOffset`.
     /// - `NOT_ENOUGH` if the offset field is not set.
     pub fn to_fixed_offset(&self) -> ParseResult<FixedOffset> {
-        FixedOffset::east(self.offset.ok_or(NOT_ENOUGH)?).ok_or(OUT_OF_RANGE)
+        FixedOffset::east(self.offset.ok_or(NOT_ENOUGH)?).map_err(|_| OUT_OF_RANGE)
     }
 
     /// Returns a parsed timezone-aware date and time out of given fields.
@@ -955,7 +955,7 @@ impl Parsed {
             (None, None) => return Err(NOT_ENOUGH),
         };
         let datetime = self.to_naive_datetime_with_offset(offset)?;
-        let offset = FixedOffset::east(offset).ok_or(OUT_OF_RANGE)?;
+        let offset = FixedOffset::east(offset).map_err(|_| OUT_OF_RANGE)?;
 
         match offset.from_local_datetime(&datetime) {
             LocalResult::None => Err(IMPOSSIBLE),

src/offset/fixed.rs

@@ -11,7 +11,7 @@ use rkyv::{Archive, Deserialize, Serialize};
 
 use super::{LocalResult, Offset, TimeZone};
 use crate::format::{scan, OUT_OF_RANGE};
-use crate::{NaiveDateTime, ParseError};
+use crate::{Error, NaiveDateTime, ParseError};
 
 /// The time zone with fixed offset, from UTC-23:59:59 to UTC+23:59:59.
 ///
@@ -35,7 +35,9 @@ impl FixedOffset {
     /// Makes a new `FixedOffset` for the Eastern Hemisphere with given timezone difference.
     /// The negative `secs` means the Western Hemisphere.
     ///
-    /// Returns `None` on the out-of-bound `secs`.
+    /// # Errors
+    ///
+    /// Returns [`Error::OutOfRange`] on the out-of-bound `secs`.
     ///
     /// # Example
     ///
@@ -49,19 +51,19 @@ impl FixedOffset {
     ///     .unwrap();
     /// assert_eq!(&datetime.to_rfc3339(), "2016-11-08T00:00:00+05:00")
     /// ```
-    #[must_use]
-    pub const fn east(secs: i32) -> Option<FixedOffset> {
-        if -86_400 < secs && secs < 86_400 {
-            Some(FixedOffset { local_minus_utc: secs })
-        } else {
-            None
+    pub const fn east(secs: i32) -> Result<FixedOffset, Error> {
+        match -86_400 < secs && secs < 86_400 {
+            true => Ok(FixedOffset { local_minus_utc: secs }),
+            false => Err(Error::OutOfRange),
         }
     }
 
     /// Makes a new `FixedOffset` for the Western Hemisphere with given timezone difference.
     /// The negative `secs` means the Eastern Hemisphere.
     ///
-    /// Returns `None` on the out-of-bound `secs`.
+    /// # Errors
+    ///
+    /// Returns [`Error::OutOfRange`] on the out-of-bound `secs`.
     ///
     /// # Example
     ///
@@ -75,12 +77,10 @@ impl FixedOffset {
     ///     .unwrap();
     /// assert_eq!(&datetime.to_rfc3339(), "2016-11-08T00:00:00-05:00")
     /// ```
-    #[must_use]
-    pub const fn west(secs: i32) -> Option<FixedOffset> {
-        if -86_400 < secs && secs < 86_400 {
-            Some(FixedOffset { local_minus_utc: -secs })
-        } else {
-            None
+    pub const fn west(secs: i32) -> Result<FixedOffset, Error> {
+        match -86_400 < secs && secs < 86_400 {
+            true => Ok(FixedOffset { local_minus_utc: -secs }),
+            false => Err(Error::OutOfRange),
         }
     }
 
@@ -102,7 +102,7 @@ impl FromStr for FixedOffset {
     type Err = ParseError;
     fn from_str(s: &str) -> Result<Self, Self::Err> {
         let (_, offset) = scan::timezone_offset(s, scan::consume_colon_maybe, false, false, true)?;
-        Self::east(offset).ok_or(OUT_OF_RANGE)
+        Self::east(offset).map_err(|_| OUT_OF_RANGE)
     }
 }
 
@@ -154,9 +154,7 @@ impl fmt::Display for FixedOffset {
 impl arbitrary::Arbitrary<'_> for FixedOffset {
     fn arbitrary(u: &mut arbitrary::Unstructured) -> arbitrary::Result<FixedOffset> {
         let secs = u.int_in_range(-86_399..=86_399)?;
-        let fixed_offset = FixedOffset::east(secs)
-            .expect("Could not generate a valid chrono::FixedOffset. It looks like implementation of Arbitrary for FixedOffset is erroneous.");
-        Ok(fixed_offset)
+        Ok(FixedOffset::east(secs).unwrap())
     }
 }
 

src/offset/local/unix.rs

@@ -156,8 +156,8 @@ impl Cache {
                 .offset();
 
             return match FixedOffset::east(offset) {
-                Some(offset) => LocalResult::Single(offset),
-                None => LocalResult::None,
+                Ok(offset) => LocalResult::Single(offset),
+                Err(_) => LocalResult::None,
             };
         }
 

src/offset/local/windows.rs

@@ -142,8 +142,8 @@ impl TzInfo {
             tz_info.assume_init()
         };
         Some(TzInfo {
-            std_offset: FixedOffset::west((tz_info.Bias + tz_info.StandardBias) * 60)?,
-            dst_offset: FixedOffset::west((tz_info.Bias + tz_info.DaylightBias) * 60)?,
+            std_offset: FixedOffset::west((tz_info.Bias + tz_info.StandardBias) * 60).ok()?,
+            dst_offset: FixedOffset::west((tz_info.Bias + tz_info.DaylightBias) * 60).ok()?,
             std_transition: system_time_from_naive_date_time(tz_info.StandardDate, year),
             dst_transition: system_time_from_naive_date_time(tz_info.DaylightDate, year),
         })