Move the icu crate to no_std (#911)

* Move uniset to no_std

* Autoreplace

* Migrate datetime to no_std

* Autoreplace

* fix errors

* fix import

* cargo fix

* Move icu core crate to no-std

* Add task for testing all of icu4x builds on nostd

* fix import

* fix warnings

Author: Manishearth

components/datetime/Cargo.toml

@@ -54,6 +54,7 @@ path = "src/lib.rs"
 bench = false  # This option is required for Benchmark CI
 
 [features]
+std = ["icu_provider/std", "icu_locid/std"]
 default = ["provider_serde"]
 bench = []
 provider_serde = ["serde", "litemap/serde"]

components/datetime/src/date.rs

@@ -2,17 +2,17 @@
 // called LICENSE at the top level of the ICU4X source tree
 // (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
 
+use core::convert::TryFrom;
+use core::ops::{Add, Sub};
+use core::str::FromStr;
 use displaydoc::Display;
 use icu_locid::Locale;
-use std::convert::TryFrom;
-use std::ops::{Add, Sub};
-use std::str::FromStr;
 use tinystr::TinyStr8;
 
 #[derive(Display, Debug)]
 pub enum DateTimeError {
     #[displaydoc("{0}")]
-    Parse(std::num::ParseIntError),
+    Parse(core::num::ParseIntError),
     #[displaydoc("{field} must be between 0-{max}")]
     Overflow { field: &'static str, max: usize },
     #[displaydoc("{field} must be between {min}-0")]
@@ -21,10 +21,11 @@ pub enum DateTimeError {
     InvalidTimeZoneOffset,
 }
 
+#[cfg(feature = "std")]
 impl std::error::Error for DateTimeError {}
 
-impl From<std::num::ParseIntError> for DateTimeError {
-    fn from(e: std::num::ParseIntError) -> Self {
+impl From<core::num::ParseIntError> for DateTimeError {
+    fn from(e: core::num::ParseIntError) -> Self {
         DateTimeError::Parse(e)
     }
 }
@@ -299,7 +300,7 @@ impl From<usize> for IsoWeekday {
         if ordinal == 0 {
             ordinal = 7;
         }
-        unsafe { std::mem::transmute(ordinal) }
+        unsafe { core::mem::transmute(ordinal) }
     }
 }
 

components/datetime/src/datetime.rs

@@ -10,6 +10,7 @@ use crate::{
         helpers::DateTimePatterns,
     },
 };
+use alloc::string::String;
 use icu_locid::Locale;
 use icu_provider::prelude::*;
 
@@ -235,17 +236,17 @@ impl<'data> DateTimeFormat<'data> {
     /// ```
     pub fn format_to_write(
         &self,
-        w: &mut impl std::fmt::Write,
+        w: &mut impl core::fmt::Write,
         value: &impl DateTimeInput,
-    ) -> std::fmt::Result {
+    ) -> core::fmt::Result {
         datetime::write_pattern(
             &self.pattern,
             self.symbols.as_ref().map(|s| s.get()),
             value,
             &self.locale,
             w,
         )
-        .map_err(|_| std::fmt::Error)
+        .map_err(|_| core::fmt::Error)
     }
 
     /// Takes a [`DateTimeInput`] implementer and returns it formatted as a string.

components/datetime/src/error.rs

@@ -16,7 +16,7 @@ pub enum DateTimeFormatError {
     Pattern(pattern::Error),
     /// An error originating from the [`Write`](std::fmt::Write) trait.
     #[displaydoc("{0}")]
-    Format(std::fmt::Error),
+    Format(core::fmt::Error),
     /// An error originating inside of the [`DataProvider`](icu_provider::DataProvider).
     #[displaydoc("{0}")]
     DataProvider(DataError),
@@ -32,6 +32,7 @@ pub enum DateTimeFormatError {
     UnsupportedField(FieldSymbol),
 }
 
+#[cfg(feature = "std")]
 impl std::error::Error for DateTimeFormatError {}
 
 impl From<pattern::Error> for DateTimeFormatError {
@@ -46,8 +47,8 @@ impl From<DataError> for DateTimeFormatError {
     }
 }
 
-impl From<std::fmt::Error> for DateTimeFormatError {
-    fn from(e: std::fmt::Error) -> Self {
+impl From<core::fmt::Error> for DateTimeFormatError {
+    fn from(e: core::fmt::Error) -> Self {
         DateTimeFormatError::Format(e)
     }
 }

components/datetime/src/fields/length.rs

@@ -2,18 +2,19 @@
 // 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::{
+use core::{
     cmp::{Ord, PartialOrd},
     convert::TryFrom,
 };
+use displaydoc::Display;
 
 #[derive(Display, Debug, PartialEq)]
 pub enum LengthError {
     #[displaydoc("Invalid length")]
     InvalidLength,
 }
 
+#[cfg(feature = "std")]
 impl std::error::Error for LengthError {}
 
 #[derive(Debug, Eq, PartialEq, Clone, Copy, Ord, PartialOrd)]

components/datetime/src/fields/mod.rs

@@ -9,7 +9,7 @@ use displaydoc::Display;
 pub use length::{FieldLength, LengthError};
 pub use symbols::*;
 
-use std::{
+use core::{
     cmp::{Ord, PartialOrd},
     convert::{TryFrom, TryInto},
 };
@@ -20,6 +20,7 @@ pub enum Error {
     InvalidLength(FieldSymbol),
 }
 
+#[cfg(feature = "std")]
 impl std::error::Error for Error {}
 
 #[derive(Debug, Eq, PartialEq, Clone, Copy, Ord, PartialOrd)]

components/datetime/src/fields/symbols.rs

@@ -3,8 +3,8 @@
 // (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
 
 use crate::fields::FieldLength;
+use core::{cmp::Ordering, convert::TryFrom};
 use displaydoc::Display;
-use std::{cmp::Ordering, convert::TryFrom};
 
 #[derive(Display, Debug, PartialEq)]
 pub enum SymbolError {
@@ -16,6 +16,7 @@ pub enum SymbolError {
     Invalid(char),
 }
 
+#[cfg(feature = "std")]
 impl std::error::Error for SymbolError {}
 
 #[derive(Debug, Eq, PartialEq, Clone, Copy)]

components/datetime/src/format/datetime.rs

@@ -9,8 +9,10 @@ use crate::fields::{self, Field, FieldLength, FieldSymbol};
 use crate::pattern::{Pattern, PatternItem};
 use crate::provider;
 use crate::provider::helpers::DateTimeSymbols;
+
+use alloc::string::ToString;
+use core::fmt;
 use icu_locid::Locale;
-use std::fmt;
 use writeable::Writeable;
 
 /// [`FormattedDateTime`] is a intermediate structure which can be retrieved as
@@ -57,7 +59,7 @@ where
 {
     fn write_to<W: fmt::Write + ?Sized>(&self, sink: &mut W) -> fmt::Result {
         write_pattern(self.pattern, self.symbols, self.datetime, self.locale, sink)
-            .map_err(|_| std::fmt::Error)
+            .map_err(|_| core::fmt::Error)
     }
 
     // TODO(#489): Implement write_len
@@ -69,12 +71,12 @@ where
 {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write_pattern(self.pattern, self.symbols, self.datetime, self.locale, f)
-            .map_err(|_| std::fmt::Error)
+            .map_err(|_| core::fmt::Error)
     }
 }
 
 // Temporary formatting number with length.
-fn format_number<W>(result: &mut W, num: isize, length: FieldLength) -> Result<(), std::fmt::Error>
+fn format_number<W>(result: &mut W, num: isize, length: FieldLength) -> Result<(), core::fmt::Error>
 where
     W: fmt::Write + ?Sized,
 {

components/datetime/src/format/time_zone.rs

@@ -2,7 +2,7 @@
 // called LICENSE at the top level of the ICU4X source tree
 // (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
 
-use std::fmt;
+use core::fmt;
 
 use crate::error::DateTimeFormatError as Error;
 use crate::fields::{self, FieldSymbol};
@@ -26,7 +26,7 @@ where
     T: TimeZoneInput,
 {
     fn write_to<W: fmt::Write + ?Sized>(&self, sink: &mut W) -> fmt::Result {
-        write_pattern(self.time_zone_format, self.time_zone, sink).map_err(|_| std::fmt::Error)
+        write_pattern(self.time_zone_format, self.time_zone, sink).map_err(|_| core::fmt::Error)
     }
 
     // TODO(#489): Implement write_len
@@ -37,7 +37,7 @@ where
     T: TimeZoneInput,
 {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write_pattern(self.time_zone_format, self.time_zone, f).map_err(|_| std::fmt::Error)
+        write_pattern(self.time_zone_format, self.time_zone, f).map_err(|_| core::fmt::Error)
     }
 }
 

components/datetime/src/format/zoned_datetime.rs

@@ -7,7 +7,7 @@ use crate::error::DateTimeFormatError as Error;
 use crate::fields::{self, FieldSymbol};
 use crate::pattern::PatternItem;
 use crate::{date::ZonedDateTimeInput, zoned_datetime::ZonedDateTimeFormat};
-use std::fmt;
+use core::fmt;
 use writeable::Writeable;
 
 use super::datetime;
@@ -27,7 +27,7 @@ where
 {
     fn write_to<W: fmt::Write + ?Sized>(&self, sink: &mut W) -> fmt::Result {
         write_pattern(self.zoned_datetime_format, self.zoned_datetime, sink)
-            .map_err(|_| std::fmt::Error)
+            .map_err(|_| core::fmt::Error)
     }
 
     // TODO(#489): Implement write_len
@@ -39,7 +39,7 @@ where
 {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write_pattern(self.zoned_datetime_format, self.zoned_datetime, f)
-            .map_err(|_| std::fmt::Error)
+            .map_err(|_| core::fmt::Error)
     }
 }
 

components/datetime/src/lib.rs

@@ -69,6 +69,11 @@
 //! [`ICU4X`]: ../icu/index.html
 //! [`Length`]: options::length
 //! [`MockDateTime`]: mock::datetime::MockDateTime
+
+#![cfg_attr(not(any(test, feature = "std")), no_std)]
+
+extern crate alloc;
+
 mod arithmetic;
 pub mod date;
 pub mod datetime;

components/datetime/src/mock/datetime.rs

@@ -4,8 +4,8 @@
 
 use crate::arithmetic;
 use crate::date::*;
-use std::convert::TryInto;
-use std::str::FromStr;
+use core::convert::TryInto;
+use core::str::FromStr;
 use tinystr::tinystr8;
 
 /// A temporary struct that implements [`DateTimeInput`]

components/datetime/src/mock/time_zone.rs

@@ -2,10 +2,11 @@
 // called LICENSE at the top level of the ICU4X source tree
 // (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
 
+use alloc::string::String;
 use tinystr::TinyStr8;
 
 use crate::date::*;
-use std::str::FromStr;
+use core::str::FromStr;
 
 // TODO(#622) link [`TimeZoneFormat`] appropriately once it is public.
 /// A temporary struct that implements [`TimeZoneInput`]

components/datetime/src/mock/zoned_datetime.rs

@@ -5,7 +5,7 @@
 use tinystr::TinyStr8;
 
 use crate::date::*;
-use std::str::FromStr;
+use core::str::FromStr;
 
 use super::{datetime::MockDateTime, time_zone::MockTimeZone};
 

components/datetime/src/options/components.rs

@@ -74,6 +74,8 @@
 //! and it is strongly recommended to never write tests that expect a particular formatted output.
 use crate::fields::{self, Field, FieldLength, FieldSymbol};
 
+use alloc::vec::Vec;
+
 use super::preferences;
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};

components/datetime/src/pattern/error.rs

@@ -22,6 +22,7 @@ pub enum Error {
     UnclosedPlaceholder,
 }
 
+#[cfg(feature = "std")]
 impl std::error::Error for Error {}
 
 impl From<fields::Error> for Error {

components/datetime/src/pattern/mod.rs

@@ -6,10 +6,17 @@ mod error;
 mod parser;
 
 use crate::fields::{self, Field, FieldLength, FieldSymbol};
+#[cfg(feature = "provider_serde")]
+use alloc::format;
+use alloc::string::String;
+#[cfg(feature = "provider_serde")]
+use alloc::string::ToString;
+use alloc::vec;
+use alloc::vec::Vec;
+use core::{convert::TryFrom, fmt};
+use core::{fmt::Write, iter::FromIterator};
 pub use error::Error;
 use parser::Parser;
-use std::{convert::TryFrom, fmt};
-use std::{fmt::Write, iter::FromIterator};
 
 #[cfg(feature = "provider_serde")]
 use serde::{

components/datetime/src/pattern/parser.rs

@@ -5,7 +5,10 @@
 use super::error::Error;
 use super::{Pattern, PatternItem};
 use crate::fields::FieldSymbol;
-use std::convert::{TryFrom, TryInto};
+use alloc::string::String;
+use alloc::vec;
+use alloc::vec::Vec;
+use core::convert::{TryFrom, TryInto};
 
 #[derive(Debug, PartialEq)]
 enum Segment {
@@ -32,7 +35,7 @@ impl<'p> Parser<'p> {
     fn handle_quoted_literal(
         &mut self,
         ch: char,
-        chars: &mut std::iter::Peekable<std::str::Chars>,
+        chars: &mut core::iter::Peekable<core::str::Chars>,
         result: &mut Vec<PatternItem>,
     ) -> Result<bool, Error> {
         if ch == '\'' {

components/datetime/src/provider/gregory.rs

@@ -2,8 +2,8 @@
 // called LICENSE at the top level of the ICU4X source tree
 // (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
 
+use alloc::borrow::Cow;
 use icu_provider::yoke::{self, *};
-use std::borrow::Cow;
 
 #[icu_provider::data_struct]
 #[derive(Debug, PartialEq, Clone, Default)]
@@ -139,8 +139,8 @@ pub mod patterns {
         pattern::{self, Pattern},
         skeleton::{Skeleton, SkeletonError},
     };
+    use core::convert::TryFrom;
     use litemap::LiteMap;
-    use std::convert::TryFrom;
 
     #[derive(Debug, PartialEq, Clone, Default)]
     #[cfg_attr(

components/datetime/src/provider/helpers.rs

@@ -9,9 +9,9 @@ use crate::options::{components, length, DateTimeFormatOptions};
 use crate::pattern::Pattern;
 use crate::provider;
 use crate::skeleton;
-use std::borrow::Cow;
+use alloc::borrow::Cow;
 
-type Result<T> = std::result::Result<T, DateTimeFormatError>;
+type Result<T> = core::result::Result<T, DateTimeFormatError>;
 
 pub trait DateTimePatterns {
     fn get_pattern_for_options(&self, options: &DateTimeFormatOptions) -> Result<Option<Pattern>>;