Implement std::error::Error

src/line.rs

@@ -1,3 +1,4 @@
+use std::fmt;
 use std::str::FromStr;
 // we still support rust that doesn't have the inherent methods
 #[allow(deprecated, unused_imports)]
@@ -32,6 +33,35 @@ pub enum Error {
     NotParsedAsLinkLine,
 }
 
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Error::FailedYearParse(s) => write!(f, "failed to parse as a year value: \"{}\"", s),
+            Error::FailedMonthParse(s) => write!(f, "failed to parse as a month value: \"{}\"", s),
+            Error::FailedWeekdayParse(s) => {
+                write!(f, "failed to parse as a weekday value: \"{}\"", s)
+            }
+            Error::InvalidLineType(s) => write!(f, "line with invalid format: \"{}\"", s),
+            Error::TypeColumnContainedNonHyphen(s) => write!(
+                f,
+                "'type' column is not a hyphen but has the value: \"{}\"",
+                s
+            ),
+            Error::CouldNotParseSaving(s) => write!(f, "failed to parse RULES column: \"{}\"", s),
+            Error::InvalidDaySpec(s) => write!(f, "invalid day specification ('ON'): \"{}\"", s),
+            Error::InvalidTimeSpecAndType(s) => write!(f, "invalid time: \"{}\"", s),
+            Error::NonWallClockInTimeSpec(s) => {
+                write!(f, "time value not given as wall time: \"{}\"", s)
+            }
+            Error::NotParsedAsRuleLine => write!(f, "failed to parse line as a rule"),
+            Error::NotParsedAsZoneLine => write!(f, "failed to parse line as a zone"),
+            Error::NotParsedAsLinkLine => write!(f, "failed to parse line as a link"),
+        }
+    }
+}
+
+impl std::error::Error for Error {}
+
 impl Default for LineParser {
     fn default() -> Self {
         LineParser {

src/table.rs

@@ -1,5 +1,4 @@
 use std::collections::hash_map::{Entry, HashMap};
-use std::error::Error as ErrorTrait;
 use std::fmt;
 
 use crate::line::{self, ChangeTime, DaySpec, Month, TimeType, Year};
@@ -352,12 +351,18 @@ pub enum Error<'line> {
 
 impl<'line> fmt::Display for Error<'line> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "{}", self.description())
+        match self {
+            Error::SurpriseContinuationLine => write!(
+                f,
+                "continuation line follows line that isn't a zone definition line"
+            ),
+            Error::UnknownRuleset(_) => {
+                write!(f, "zone definition refers to a ruleset that isn't defined")
+            }
+            Error::DuplicateLink(_) => write!(f, "link line with name that already exists"),
+            Error::DuplicateZone => write!(f, "zone line with name that already exists"),
+        }
     }
 }
 
-impl<'line> ErrorTrait for Error<'line> {
-    fn description(&self) -> &str {
-        "interpretation error"
-    }
-}
+impl<'line> std::error::Error for Error<'line> {}