Expose rkyv features as features for chrono users.

rkyv by default serializes usize as u32. This isn't ideal
on most modern platforms and unfortunately is configured through
a feature flag.

If we just set `default-features = false` in the rkyv Cargo
dependency, the crate fails to compile because all the size features
are mutually exclusive. On the other hand if we want to
e.g., change the serialization of usize to 64-bit and
we also want to use chrono this currently fails to compile
because chrono always enables rkyv/size_32.

This re-exports the relevant rkyv features so users can
choose which serialization to enable. The approach
is similar to what the ordered-float crate does:

https://github.com/reem/rust-ordered-float/blob/8111b345372632893af0b8aa12152f3dc7278aba/Cargo.toml#L37

Signed-off-by: Gerd Zellweger <mail@gerdzellweger.com>

Cargo.toml

@@ -17,6 +17,7 @@ rust-version = "1.57.0"
 name = "chrono"
 
 [features]
+# Don't forget to adjust `ALL_NON_EXCLUSIVE_FEATURES` in CI scripts when adding a feature or an optional dependency.
 default = ["clock", "std", "wasmbind"]
 alloc = []
 libc = []
@@ -25,12 +26,20 @@ std = ["alloc"]
 clock = ["std", "winapi", "iana-time-zone", "android-tzdata"]
 wasmbind = ["wasm-bindgen", "js-sys"]
 unstable-locales = ["pure-rust-locales"]
+rkyv = ["rkyv-32"]
+# Note that rkyv-16, rkyv-32, and rkyv-64 are mutually exclusive.
+rkyv-16 = ["dep:rkyv", "rkyv?/size_16"]
+rkyv-32 = ["dep:rkyv", "rkyv?/size_32"]
+rkyv-64 = ["dep:rkyv", "rkyv?/size_64"]
+rkyv-validation = ["rkyv?/validation"]
+# Features for internal use only:
 __internal_bench = []
+__internal-rkyv = ["dep:rkyv"]
 
 [dependencies]
 serde = { version = "1.0.99", default-features = false, optional = true }
 pure-rust-locales = { version = "0.7", optional = true }
-rkyv = { version = "0.7", optional = true }
+rkyv = { version = "0.7", optional = true, default-features = false }
 arbitrary = { version = "1.0.0", features = ["derive"], optional = true }
 
 [target.'cfg(all(target_arch = "wasm32", not(any(target_os = "emscripten", target_os = "wasi"))))'.dependencies]

src/datetime/mod.rs

@@ -28,7 +28,7 @@ use crate::offset::Local;
 use crate::offset::{FixedOffset, Offset, TimeZone, Utc};
 use crate::{Datelike, Months, TimeDelta, Timelike, Weekday};
 
-#[cfg(feature = "rkyv")]
+#[cfg(feature = "__internal-rkyv")]
 use rkyv::{Archive, Deserialize, Serialize};
 
 /// documented at re-export site
@@ -73,7 +73,10 @@ pub enum SecondsFormat {
 /// the general-purpose constructors are all via the methods on the
 /// [`TimeZone`](./offset/trait.TimeZone.html) implementations.
 #[derive(Clone)]
-#[cfg_attr(feature = "rkyv", derive(Archive, Deserialize, Serialize))]
+#[cfg_attr(
+    any(feature = "rkyv_16", feature = "rkyv_32", feature = "rkyv_64"),
+    derive(Archive, Deserialize, Serialize)
+)]
 pub struct DateTime<Tz: TimeZone> {
     datetime: NaiveDateTime,
     offset: Tz::Offset,

src/lib.rs

@@ -544,7 +544,7 @@ pub mod serde {
 /// Zero-copy serialization/deserialization with rkyv.
 ///
 /// This module re-exports the `Archived*` versions of chrono's types.
-#[cfg(feature = "rkyv")]
+#[cfg(feature = "__internal-rkyv")]
 pub mod rkyv {
     pub use crate::datetime::ArchivedDateTime;
     pub use crate::month::ArchivedMonth;

src/month.rs

@@ -1,6 +1,6 @@
 use core::fmt;
 
-#[cfg(feature = "rkyv")]
+#[cfg(feature = "__internal-rkyv")]
 use rkyv::{Archive, Deserialize, Serialize};
 
 use crate::OutOfRange;
@@ -29,9 +29,12 @@ use crate::OutOfRange;
 /// Can be Serialized/Deserialized with serde
 // Actual implementation is zero-indexed, API intended as 1-indexed for more intuitive behavior.
 #[derive(PartialEq, Eq, Copy, Clone, Debug, Hash, PartialOrd, Ord)]
-#[cfg_attr(feature = "rkyv", derive(Archive, Deserialize, Serialize))]
 #[cfg_attr(
-    feature = "rkyv",
+    any(feature = "rkyv_16", feature = "rkyv_32", feature = "rkyv_64"),
+    derive(Archive, Deserialize, Serialize)
+)]
+#[cfg_attr(
+    any(feature = "rkyv_16", feature = "rkyv_32", feature = "rkyv_64"),
     archive_attr(derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Debug, Hash))
 )]
 #[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]

src/naive/date.rs

@@ -9,7 +9,7 @@ use core::iter::FusedIterator;
 use core::ops::{Add, AddAssign, RangeInclusive, Sub, SubAssign};
 use core::{fmt, str};
 
-#[cfg(feature = "rkyv")]
+#[cfg(feature = "__internal-rkyv")]
 use rkyv::{Archive, Deserialize, Serialize};
 
 /// L10n locales.
@@ -190,9 +190,12 @@ impl Days {
 ///
 /// [proleptic Gregorian date]: crate::NaiveDate#calendar-date
 #[derive(PartialEq, Eq, Hash, PartialOrd, Ord, Copy, Clone)]
-#[cfg_attr(feature = "rkyv", derive(Archive, Deserialize, Serialize))]
 #[cfg_attr(
-    feature = "rkyv",
+    any(feature = "rkyv_16", feature = "rkyv_32", feature = "rkyv_64"),
+    derive(Archive, Deserialize, Serialize)
+)]
+#[cfg_attr(
+    any(feature = "rkyv_16", feature = "rkyv_32", feature = "rkyv_64"),
     archive_attr(derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Debug, Hash))
 )]
 pub struct NaiveDate {

src/naive/datetime/mod.rs

@@ -10,7 +10,7 @@ use core::ops::{Add, AddAssign, Sub, SubAssign};
 use core::time::Duration;
 use core::{fmt, str};
 
-#[cfg(feature = "rkyv")]
+#[cfg(feature = "__internal-rkyv")]
 use rkyv::{Archive, Deserialize, Serialize};
 
 #[cfg(feature = "alloc")]
@@ -72,9 +72,12 @@ pub const MAX_DATETIME: NaiveDateTime = NaiveDateTime::MAX;
 /// assert_eq!(dt.num_seconds_from_midnight(), 33011);
 /// ```
 #[derive(PartialEq, Eq, Hash, PartialOrd, Ord, Copy, Clone)]
-#[cfg_attr(feature = "rkyv", derive(Archive, Deserialize, Serialize))]
 #[cfg_attr(
-    feature = "rkyv",
+    any(feature = "rkyv_16", feature = "rkyv_32", feature = "rkyv_64"),
+    derive(Archive, Deserialize, Serialize)
+)]
+#[cfg_attr(
+    any(feature = "rkyv_16", feature = "rkyv_32", feature = "rkyv_64"),
     archive_attr(derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Debug, Hash))
 )]
 #[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]

src/naive/isoweek.rs

@@ -7,7 +7,7 @@ use core::fmt;
 
 use super::internals::{DateImpl, Of, YearFlags};
 
-#[cfg(feature = "rkyv")]
+#[cfg(feature = "__internal-rkyv")]
 use rkyv::{Archive, Deserialize, Serialize};
 
 /// ISO 8601 week.
@@ -17,9 +17,12 @@ use rkyv::{Archive, Deserialize, Serialize};
 /// One can retrieve this type from the existing [`Datelike`](../trait.Datelike.html) types
 /// via the [`Datelike::iso_week`](../trait.Datelike.html#tymethod.iso_week) method.
 #[derive(PartialEq, Eq, PartialOrd, Ord, Copy, Clone, Hash)]
-#[cfg_attr(feature = "rkyv", derive(Archive, Deserialize, Serialize))]
 #[cfg_attr(
-    feature = "rkyv",
+    any(feature = "rkyv_16", feature = "rkyv_32", feature = "rkyv_64"),
+    derive(Archive, Deserialize, Serialize)
+)]
+#[cfg_attr(
+    any(feature = "rkyv_16", feature = "rkyv_32", feature = "rkyv_64"),
     archive_attr(derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Debug, Hash))
 )]
 pub struct IsoWeek {

src/naive/time/mod.rs

@@ -9,7 +9,7 @@ use core::ops::{Add, AddAssign, Sub, SubAssign};
 use core::time::Duration;
 use core::{fmt, str};
 
-#[cfg(feature = "rkyv")]
+#[cfg(feature = "__internal-rkyv")]
 use rkyv::{Archive, Deserialize, Serialize};
 
 #[cfg(feature = "alloc")]
@@ -199,9 +199,12 @@ mod tests;
 /// Since Chrono alone cannot determine any existence of leap seconds,
 /// **there is absolutely no guarantee that the leap second read has actually happened**.
 #[derive(PartialEq, Eq, Hash, PartialOrd, Ord, Copy, Clone)]
-#[cfg_attr(feature = "rkyv", derive(Archive, Deserialize, Serialize))]
 #[cfg_attr(
-    feature = "rkyv",
+    any(feature = "rkyv_16", feature = "rkyv_32", feature = "rkyv_64"),
+    derive(Archive, Deserialize, Serialize)
+)]
+#[cfg_attr(
+    any(feature = "rkyv_16", feature = "rkyv_32", feature = "rkyv_64"),
     archive_attr(derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Debug, Hash))
 )]
 pub struct NaiveTime {

src/offset/fixed.rs

@@ -6,7 +6,7 @@
 use core::fmt;
 use core::str::FromStr;
 
-#[cfg(feature = "rkyv")]
+#[cfg(feature = "__internal-rkyv")]
 use rkyv::{Archive, Deserialize, Serialize};
 
 use super::{LocalResult, Offset, TimeZone};
@@ -20,8 +20,14 @@ use crate::{NaiveDateTime, ParseError};
 /// `DateTime<FixedOffset>` instances. See the [`east_opt`](#method.east_opt) and
 /// [`west_opt`](#method.west_opt) methods for examples.
 #[derive(PartialEq, Eq, Hash, Copy, Clone)]
-#[cfg_attr(feature = "rkyv", derive(Archive, Deserialize, Serialize))]
-#[cfg_attr(feature = "rkyv", archive_attr(derive(Clone, Copy, PartialEq, Eq, Hash, Debug)))]
+#[cfg_attr(
+    any(feature = "rkyv_16", feature = "rkyv_32", feature = "rkyv_64"),
+    derive(Archive, Deserialize, Serialize)
+)]
+#[cfg_attr(
+    any(feature = "rkyv_16", feature = "rkyv_32", feature = "rkyv_64"),
+    archive_attr(derive(Clone, Copy, PartialEq, Eq, Hash, Debug))
+)]
 pub struct FixedOffset {
     local_minus_utc: i32,
 }

src/offset/local/mod.rs

@@ -3,7 +3,7 @@
 
 //! The local (system) time zone.
 
-#[cfg(feature = "rkyv")]
+#[cfg(feature = "__internal-rkyv")]
 use rkyv::{Archive, Deserialize, Serialize};
 
 use super::fixed::FixedOffset;
@@ -101,8 +101,14 @@ mod tz_info;
 /// assert!(dt1 >= dt2);
 /// ```
 #[derive(Copy, Clone, Debug)]
-#[cfg_attr(feature = "rkyv", derive(Archive, Deserialize, Serialize))]
-#[cfg_attr(feature = "rkyv", archive_attr(derive(Clone, Copy, Debug)))]
+#[cfg_attr(
+    any(feature = "rkyv_16", feature = "rkyv_32", feature = "rkyv_64"),
+    derive(Archive, Deserialize, Serialize)
+)]
+#[cfg_attr(
+    any(feature = "rkyv_16", feature = "rkyv_32", feature = "rkyv_64"),
+    archive_attr(derive(Clone, Copy, Debug))
+)]
 #[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
 pub struct Local;
 

src/offset/utc.rs

@@ -14,7 +14,7 @@ use core::fmt;
 ))]
 use std::time::{SystemTime, UNIX_EPOCH};
 
-#[cfg(feature = "rkyv")]
+#[cfg(feature = "__internal-rkyv")]
 use rkyv::{Archive, Deserialize, Serialize};
 
 use super::{FixedOffset, LocalResult, Offset, TimeZone};
@@ -40,8 +40,14 @@ use crate::DateTime;
 /// assert_eq!(Utc.with_ymd_and_hms(1970, 1, 1, 0, 1, 1).unwrap(), dt);
 /// ```
 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
-#[cfg_attr(feature = "rkyv", derive(Archive, Deserialize, Serialize))]
-#[cfg_attr(feature = "rkyv", archive_attr(derive(Clone, Copy, PartialEq, Eq, Debug, Hash)))]
+#[cfg_attr(
+    any(feature = "rkyv_16", feature = "rkyv_32", feature = "rkyv_64"),
+    derive(Archive, Deserialize, Serialize)
+)]
+#[cfg_attr(
+    any(feature = "rkyv_16", feature = "rkyv_32", feature = "rkyv_64"),
+    archive_attr(derive(Clone, Copy, PartialEq, Eq, Debug, Hash))
+)]
 #[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
 pub struct Utc;
 

src/time_delta.rs

@@ -16,7 +16,7 @@ use core::{fmt, i64};
 #[cfg(feature = "std")]
 use std::error::Error;
 
-#[cfg(feature = "rkyv")]
+#[cfg(feature = "__internal-rkyv")]
 use rkyv::{Archive, Deserialize, Serialize};
 
 /// The number of nanoseconds in a microsecond.
@@ -51,9 +51,12 @@ macro_rules! try_opt {
 ///
 /// This also allows for the negative duration; see individual methods for details.
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
-#[cfg_attr(feature = "rkyv", derive(Archive, Deserialize, Serialize))]
 #[cfg_attr(
-    feature = "rkyv",
+    any(feature = "rkyv_16", feature = "rkyv_32", feature = "rkyv_64"),
+    derive(Archive, Deserialize, Serialize)
+)]
+#[cfg_attr(
+    any(feature = "rkyv_16", feature = "rkyv_32", feature = "rkyv_64"),
     archive_attr(derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Debug, Hash))
 )]
 pub struct TimeDelta {

src/weekday.rs

@@ -1,6 +1,6 @@
 use core::fmt;
 
-#[cfg(feature = "rkyv")]
+#[cfg(feature = "__internal-rkyv")]
 use rkyv::{Archive, Deserialize, Serialize};
 
 use crate::OutOfRange;
@@ -30,8 +30,14 @@ use crate::OutOfRange;
 /// assert_eq!(sunday.pred(), Weekday::Sat);
 /// ```
 #[derive(PartialEq, Eq, Copy, Clone, Debug, Hash)]
-#[cfg_attr(feature = "rkyv", derive(Archive, Deserialize, Serialize))]
-#[cfg_attr(feature = "rkyv", archive_attr(derive(Clone, Copy, PartialEq, Eq, Debug, Hash)))]
+#[cfg_attr(
+    any(feature = "rkyv_16", feature = "rkyv_32", feature = "rkyv_64"),
+    derive(Archive, Deserialize, Serialize)
+)]
+#[cfg_attr(
+    any(feature = "rkyv_16", feature = "rkyv_32", feature = "rkyv_64"),
+    archive_attr(derive(Clone, Copy, PartialEq, Eq, Debug, Hash))
+)]
 #[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
 pub enum Weekday {
     /// Monday.