Replace thiserror with displaydoc

components/datetime/Cargo.toml

@@ -36,7 +36,7 @@ litemap = { version = "0.2", path = "../../utils/litemap", features = ["serde"]
 tinystr = { version = "0.4.5" }
 serde = { version = "1.0", features = ["derive"], optional = true }
 smallvec = "1.6"
-thiserror = "1.0"
+displaydoc = { version = "0.2.3", default-features = false }
 
 [dev-dependencies]
 criterion = "0.3"

components/datetime/src/date.rs

@@ -2,25 +2,33 @@
 // called LICENSE at the top level of the ICU4X source tree
 // (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
 
+use displaydoc::Display;
 use icu_locid::Locale;
 use std::convert::TryFrom;
 use std::ops::{Add, Sub};
 use std::str::FromStr;
-use thiserror::Error;
 use tinystr::TinyStr8;
 
-#[derive(Error, Debug)]
+#[derive(Display, Debug)]
 pub enum DateTimeError {
-    #[error(transparent)]
-    Parse(#[from] std::num::ParseIntError),
-    #[error("{field} must be between 0-{max}")]
+    #[displaydoc("{0}")]
+    Parse(std::num::ParseIntError),
+    #[displaydoc("{field} must be between 0-{max}")]
     Overflow { field: &'static str, max: usize },
-    #[error("{field} must be between {min}-0")]
+    #[displaydoc("{field} must be between {min}-0")]
     Underflow { field: &'static str, min: isize },
-    #[error("Failed to parse time-zone offset")]
+    #[displaydoc("Failed to parse time-zone offset")]
     InvalidTimeZoneOffset,
 }
 
+impl std::error::Error for DateTimeError {}
+
+impl From<std::num::ParseIntError> for DateTimeError {
+    fn from(e: std::num::ParseIntError) -> Self {
+        DateTimeError::Parse(e)
+    }
+}
+
 /// Representation of a formattable calendar date. Supports dates in any calendar system that uses
 /// solar days indexed by an era, year, month, and day.
 ///

components/datetime/src/error.rs

@@ -5,29 +5,55 @@
 use crate::fields::FieldSymbol;
 use crate::pattern;
 use crate::skeleton::SkeletonError;
+use displaydoc::Display;
 use icu_provider::prelude::DataError;
-use thiserror::Error;
 
 /// A list of possible error outcomes for the [`DateTimeFormat`](crate::DateTimeFormat) struct.
-#[derive(Error, Debug)]
+#[derive(Display, Debug)]
 pub enum DateTimeFormatError {
     /// An error originating from parsing a pattern.
-    #[error(transparent)]
-    Pattern(#[from] pattern::Error),
+    #[displaydoc("{0}")]
+    Pattern(pattern::Error),
     /// An error originating from the [`Write`](std::fmt::Write) trait.
-    #[error(transparent)]
-    Format(#[from] std::fmt::Error),
+    #[displaydoc("{0}")]
+    Format(std::fmt::Error),
     /// An error originating inside of the [`DataProvider`](icu_provider::DataProvider).
-    #[error(transparent)]
-    DataProvider(#[from] DataError),
+    #[displaydoc("{0}")]
+    DataProvider(DataError),
     /// An error originating from a missing field in datetime input.
     /// TODO: How can we return which field was missing?
-    #[error("Missing input field")]
+    #[displaydoc("Missing input field")]
     MissingInputField,
     /// An error originating from skeleton matching.
-    #[error(transparent)]
-    Skeleton(#[from] SkeletonError),
+    #[displaydoc("{0}")]
+    Skeleton(SkeletonError),
     /// An error originating from an unsupported field in a datetime format.
-    #[error("Unsupported field: {0:?}")]
+    #[displaydoc("Unsupported field: {0:?}")]
     UnsupportedField(FieldSymbol),
 }
+
+impl std::error::Error for DateTimeFormatError {}
+
+impl From<pattern::Error> for DateTimeFormatError {
+    fn from(e: pattern::Error) -> Self {
+        DateTimeFormatError::Pattern(e)
+    }
+}
+
+impl From<DataError> for DateTimeFormatError {
+    fn from(e: DataError) -> Self {
+        DateTimeFormatError::DataProvider(e)
+    }
+}
+
+impl From<std::fmt::Error> for DateTimeFormatError {
+    fn from(e: std::fmt::Error) -> Self {
+        DateTimeFormatError::Format(e)
+    }
+}
+
+impl From<SkeletonError> for DateTimeFormatError {
+    fn from(e: SkeletonError) -> Self {
+        DateTimeFormatError::Skeleton(e)
+    }
+}

components/datetime/src/fields/length.rs

@@ -2,18 +2,20 @@
 // called LICENSE at the top level of the ICU4X source tree
 // (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
 
+use displaydoc::Display;
 use std::{
     cmp::{Ord, PartialOrd},
     convert::TryFrom,
 };
-use thiserror::Error;
 
-#[derive(Error, Debug, PartialEq)]
+#[derive(Display, Debug, PartialEq)]
 pub enum LengthError {
-    #[error("Invalid length")]
+    #[displaydoc("Invalid length")]
     InvalidLength,
 }
 
+impl std::error::Error for LengthError {}
+
 #[derive(Debug, Eq, PartialEq, Clone, Copy, Ord, PartialOrd)]
 #[cfg_attr(
     feature = "provider_serde",

components/datetime/src/fields/mod.rs

@@ -5,21 +5,23 @@
 mod length;
 pub(crate) mod symbols;
 
+use displaydoc::Display;
 pub use length::{FieldLength, LengthError};
 pub use symbols::*;
-use thiserror::Error;
 
 use std::{
     cmp::{Ord, PartialOrd},
     convert::{TryFrom, TryInto},
 };
 
-#[derive(Error, Debug)]
+#[derive(Display, Debug)]
 pub enum Error {
-    #[error("Field {0:?} is not a valid length")]
+    #[displaydoc("Field {0:?} is not a valid length")]
     InvalidLength(FieldSymbol),
 }
 
+impl std::error::Error for Error {}
+
 #[derive(Debug, Eq, PartialEq, Clone, Copy, Ord, PartialOrd)]
 #[cfg_attr(
     feature = "provider_serde",

components/datetime/src/fields/symbols.rs

@@ -3,19 +3,21 @@
 // (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
 
 use crate::fields::FieldLength;
+use displaydoc::Display;
 use std::{cmp::Ordering, convert::TryFrom};
-use thiserror::Error;
 
-#[derive(Error, Debug, PartialEq)]
+#[derive(Display, Debug, PartialEq)]
 pub enum SymbolError {
     /// Unknown field symbol.
-    #[error("Unknown field symbol: {0}")]
+    #[displaydoc("Unknown field symbol: {0}")]
     Unknown(u8),
     /// Invalid character for a field symbol.
-    #[error("Invalid character for a field symbol: {0}")]
+    #[displaydoc("Invalid character for a field symbol: {0}")]
     Invalid(char),
 }
 
+impl std::error::Error for SymbolError {}
+
 #[derive(Debug, Eq, PartialEq, Clone, Copy)]
 #[cfg_attr(
     feature = "provider_serde",