add abi_stable feature

Cargo.toml

@@ -26,6 +26,7 @@ std = ["alloc"]
 clock = ["winapi", "iana-time-zone", "android-tzdata", "now"]
 now = ["std"]
 oldtime = []
+abi_stable = ["dep:abi_stable"]
 wasmbind = ["wasm-bindgen", "js-sys"]
 unstable-locales = ["pure-rust-locales"]
 # Note that rkyv-16, rkyv-32, and rkyv-64 are mutually exclusive.
@@ -44,6 +45,7 @@ serde = { version = "1.0.99", default-features = false, optional = true }
 pure-rust-locales = { version = "0.8", optional = true }
 rkyv = { version = "0.7.43", optional = true, default-features = false }
 arbitrary = { version = "1.0.0", features = ["derive"], optional = true }
+abi_stable = { version = "0.11.3", optional = true }
 
 [target.'cfg(all(target_arch = "wasm32", not(any(target_os = "emscripten", target_os = "wasi"))))'.dependencies]
 wasm-bindgen = { version = "0.2", optional = true }

src/datetime/mod.rs

@@ -56,6 +56,9 @@ mod tests;
     archive(compare(PartialEq, PartialOrd))
 )]
 #[cfg_attr(feature = "rkyv-validation", archive(check_bytes))]
+#[cfg_attr(feature = "abi_stable", derive(abi_stable::StableAbi))]
+#[cfg_attr(feature = "abi_stable", repr(C))]
+#[cfg_attr(feature = "abi_stable", sabi(bound(Tz::Offset: abi_stable::StableAbi)))]
 pub struct DateTime<Tz: TimeZone> {
     datetime: NaiveDateTime,
     offset: Tz::Offset,
@@ -1839,3 +1842,17 @@ fn test_decodable_json_timestamps<FUtc, FFixed, FLocal, E>(
         Utc.with_ymd_and_hms(1969, 12, 31, 23, 59, 59).unwrap()
     );
 }
+
+#[cfg(all(feature = "abi_stable", test))]
+mod test_abi_stable {
+    use super::*;
+    struct _DateTimeUtcIsAbiStable
+    where
+        DateTime<Utc>: abi_stable::StableAbi;
+    struct _DateTimeFixedOffsetIsAbiStable
+    where
+        DateTime<FixedOffset>: abi_stable::StableAbi;
+    struct _DateTimeLocalIsAbiStable
+    where
+        DateTime<Local>: abi_stable::StableAbi;
+}

src/month.rs

@@ -226,6 +226,8 @@ impl num_traits::FromPrimitive for Month {
 /// A duration in calendar months
 #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq, PartialOrd, Ord)]
 #[cfg_attr(all(feature = "arbitrary", feature = "std"), derive(arbitrary::Arbitrary))]
+#[cfg_attr(feature = "abi_stable", derive(abi_stable::StableAbi))]
+#[cfg_attr(feature = "abi_stable", repr(transparent))]
 pub struct Months(pub(crate) u32);
 
 impl Months {

src/naive/date/mod.rs

@@ -99,6 +99,8 @@ mod tests;
     archive_attr(derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Debug, Hash))
 )]
 #[cfg_attr(feature = "rkyv-validation", archive(check_bytes))]
+#[cfg_attr(feature = "abi_stable", derive(abi_stable::StableAbi))]
+#[cfg_attr(feature = "abi_stable", repr(transparent))]
 pub struct NaiveDate {
     yof: NonZeroI32, // (year << 13) | of
 }

src/naive/datetime/mod.rs

@@ -82,6 +82,8 @@ pub const MAX_DATETIME: NaiveDateTime = NaiveDateTime::MAX;
 )]
 #[cfg_attr(feature = "rkyv-validation", archive(check_bytes))]
 #[cfg_attr(all(feature = "arbitrary", feature = "std"), derive(arbitrary::Arbitrary))]
+#[cfg_attr(feature = "abi_stable", derive(abi_stable::StableAbi))]
+#[cfg_attr(feature = "abi_stable", repr(C))]
 pub struct NaiveDateTime {
     date: NaiveDate,
     time: NaiveTime,

src/naive/time/mod.rs

@@ -209,6 +209,8 @@ mod tests;
     archive_attr(derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Debug, Hash))
 )]
 #[cfg_attr(feature = "rkyv-validation", archive(check_bytes))]
+#[cfg_attr(feature = "abi_stable", derive(abi_stable::StableAbi))]
+#[cfg_attr(feature = "abi_stable", repr(C))]
 pub struct NaiveTime {
     secs: u32,
     frac: u32,

src/offset/fixed.rs

@@ -27,6 +27,8 @@ use crate::naive::{NaiveDate, NaiveDateTime};
     archive_attr(derive(Clone, Copy, PartialEq, Eq, Hash, Debug))
 )]
 #[cfg_attr(feature = "rkyv-validation", archive(check_bytes))]
+#[cfg_attr(feature = "abi_stable", derive(abi_stable::StableAbi))]
+#[cfg_attr(feature = "abi_stable", repr(transparent))]
 pub struct FixedOffset {
     local_minus_utc: i32,
 }

src/offset/local/mod.rs

@@ -115,6 +115,8 @@ mod tz_info;
 )]
 #[cfg_attr(feature = "rkyv-validation", archive(check_bytes))]
 #[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
+#[cfg_attr(feature = "abi_stable", derive(abi_stable::StableAbi))]
+#[cfg_attr(feature = "abi_stable", repr(transparent))]
 pub struct Local;
 
 impl Local {

src/offset/utc.rs

@@ -49,6 +49,8 @@ use crate::{Date, DateTime};
 )]
 #[cfg_attr(feature = "rkyv-validation", archive(check_bytes))]
 #[cfg_attr(all(feature = "arbitrary", feature = "std"), derive(arbitrary::Arbitrary))]
+#[cfg_attr(feature = "abi_stable", derive(abi_stable::StableAbi))]
+#[cfg_attr(feature = "abi_stable", repr(transparent))]
 pub struct Utc;
 
 #[cfg(feature = "now")]