Fix parsing bugs related to UTC Designator usage (#197)

`DateTime`, `Date`, and `Time` should reject when the UTC designator `Z`
is present.

src/builtins/core/time.rs

@@ -467,6 +467,8 @@ impl FromStr for PlainTime {
 
 #[cfg(test)]
 mod tests {
+    use core::str::FromStr;
+
     use crate::{
         builtins::core::Duration,
         iso::IsoTime,
@@ -797,4 +799,19 @@ mod tests {
                 .unwrap()
         );
     }
+
+    #[test]
+    fn invalid_time_from_strs() {
+        // UTC designator case
+        let invalid_cases = [
+            "2019-10-01T09:00:00Z",
+            "2019-10-01T09:00:00Z[UTC]",
+            "09:00:00Z[UTC]",
+            "09:00:00Z",
+        ];
+        for invalid_str in invalid_cases {
+            let err = PlainTime::from_str(invalid_str);
+            assert!(err.is_err());
+        }
+    }
 }

src/builtins/core/zoneddatetime.rs

@@ -27,7 +27,7 @@ use crate::{
     rounding::{IncrementRounder, Round},
     temporal_assert,
     time::EpochNanoseconds,
-    Sign, TemporalError, TemporalResult,
+    Sign, TemporalError, TemporalResult, TemporalUnwrap,
 };
 
 /// A struct representing a partial `ZonedDateTime`.
@@ -864,12 +864,10 @@ impl ZonedDateTime {
         offset_option: OffsetDisambiguation,
         provider: &impl TimeZoneProvider,
     ) -> TemporalResult<Self> {
-        let parse_result = parsers::parse_date_time(source)?;
+        let parse_result = parsers::parse_zoned_date_time(source)?;
 
-        let Some(annotation) = parse_result.tz else {
-            return Err(TemporalError::r#type()
-                .with_message("Time zone annotation is required for ZonedDateTime string."));
-        };
+        // NOTE (nekevss): `parse_zoned_date_time` guarantees that this value exists.
+        let annotation = parse_result.tz.temporal_unwrap()?;
 
         let timezone = match annotation.tz {
             TimeZoneRecord::Name(s) => {

src/parsers.rs

@@ -700,7 +700,27 @@ fn parse_ixdtf(source: &str, variant: ParseVariant) -> TemporalResult<IxdtfParse
 /// A utility function for parsing a `DateTime` string
 #[inline]
 pub(crate) fn parse_date_time(source: &str) -> TemporalResult<IxdtfParseRecord> {
-    parse_ixdtf(source, ParseVariant::DateTime)
+    let record = parse_ixdtf(source, ParseVariant::DateTime)?;
+
+    if record.offset == Some(UtcOffsetRecordOrZ::Z) {
+        return Err(TemporalError::range()
+            .with_message("UTC designator is not valid for DateTime parsing."));
+    }
+
+    Ok(record)
+}
+
+#[inline]
+pub(crate) fn parse_zoned_date_time(source: &str) -> TemporalResult<IxdtfParseRecord> {
+    let record = parse_ixdtf(source, ParseVariant::DateTime)?;
+
+    // TODO: Support rejecting subminute precision in time zone annootations
+    if record.tz.is_none() {
+        return Err(TemporalError::range()
+            .with_message("Time zone annotation is required for parsing a zoned date time."));
+    }
+
+    Ok(record)
 }
 
 pub(crate) struct IxdtfParseInstantRecord {
@@ -760,11 +780,17 @@ pub(crate) fn parse_time(source: &str) -> TemporalResult<TimeRecord> {
     let time_record = parse_ixdtf(source, ParseVariant::Time);
 
     let time_err = match time_record {
-        Ok(time) => return time.time.temporal_unwrap(),
+        Ok(time) => {
+            if time.offset == Some(UtcOffsetRecordOrZ::Z) {
+                return Err(TemporalError::range()
+                    .with_message("UTC designator is not valid for DateTime parsing."));
+            }
+            return time.time.temporal_unwrap();
+        }
         Err(e) => TemporalError::range().with_message(format!("{e}")),
     };
 
-    let dt_parse = parse_ixdtf(source, ParseVariant::DateTime);
+    let dt_parse = parse_date_time(source);
 
     match dt_parse {
         Ok(dt) if dt.time.is_some() => Ok(dt.time.temporal_unwrap()?),