Fix fixed offset timezone conversion bug.

See PyO3#3267

src/conversions/chrono.rs

@@ -216,8 +216,8 @@ impl FromPyObject<'_> for NaiveDateTime {
 
 impl<Tz: TimeZone> ToPyObject for DateTime<Tz> {
     fn to_object(&self, py: Python<'_>) -> PyObject {
-        let date = self.naive_utc().date();
-        let time = self.naive_utc().time();
+        let date = self.naive_local().date();
+        let time = self.naive_local().time();
         let yy = date.year();
         let mm = date.month() as u8;
         let dd = date.day() as u8;
@@ -261,7 +261,7 @@ impl FromPyObject<'_> for DateTime<FixedOffset> {
             NaiveTime::from_hms_micro_opt(h, m, s, ms)
                 .ok_or_else(|| PyValueError::new_err("invalid or out-of-range time"))?,
         );
-        Ok(DateTime::from_utc(dt, tz))
+        Ok(DateTime::from_local(dt, tz))
     }
 }
 
@@ -372,6 +372,7 @@ impl FromPyObject<'_> for Utc {
 #[cfg(test)]
 mod tests {
     use std::{cmp::Ordering, panic};
+    use crate::types::PyDict;
 
     use super::*;
 
@@ -607,7 +608,7 @@ mod tests {
                         .and_hms_micro_opt(hour, minute, ssecond, ms)
                         .unwrap();
                     let datetime =
-                        DateTime::<FixedOffset>::from_utc(datetime, offset).to_object(py);
+                        DateTime::<FixedOffset>::from_local(datetime, offset).to_object(py);
                     let datetime: &PyDateTime = datetime.extract(py).unwrap();
                     let py_tz = offset.to_object(py);
                     let py_tz = py_tz.downcast(py).unwrap();
@@ -700,7 +701,7 @@ mod tests {
                         .unwrap()
                         .and_hms_micro_opt(hour, minute, second, ms)
                         .unwrap();
-                    let datetime = DateTime::<FixedOffset>::from_utc(datetime, offset);
+                    let datetime = DateTime::<FixedOffset>::from_local(datetime, offset);
                     assert_eq!(
                         py_datetime, datetime,
                         "{}: {} != {}",
@@ -729,6 +730,30 @@ mod tests {
         })
     }
 
+    #[test]
+    fn test_pyo3_offset_fixed_frompyobject_created_in_python() {
+        Python::with_gil(|py| {
+            let code = r#"
+import datetime
+t = datetime.datetime.fromtimestamp(12345).replace(tzinfo=datetime.timezone(datetime.timedelta(hours=-8)))
+            "#.trim();
+
+            let globals = PyDict::new(py);
+            py.run(code, Some(globals), None).unwrap();
+
+            // Get ISO 8601 string from python
+            let t = globals.get_item("t").unwrap();
+            let py_iso_str = t.call_method0("isoformat").unwrap();
+
+            // Get ISO 8601 string from rust
+            let t = t.extract::<DateTime<FixedOffset>>().unwrap();
+            let rust_iso_str = t.to_rfc3339();
+
+            // They should be equal
+            assert_eq!(py_iso_str.to_string(), rust_iso_str);
+        })
+    }
+
     #[test]
     fn test_pyo3_offset_fixed_topyobject() {
         Python::with_gil(|py| {