Stub out tzdb support for Windows and POSIX tz string

Cargo.toml

@@ -28,9 +28,11 @@ log = { version = "0.4.0", optional = true }
 
 tzif = { version = "0.2.3", optional = true }
 iana-time-zone = "0.1.61"
+jiff-tzdb = { version = "0.1.1", optional = true }
+combine = { version = "4.6.7", optional = true }
 
 [features]
 log = ["dep:log"]
 experimental = ["tzdb"]
-tzdb = ["dep:tzif", "std"]
+tzdb = ["dep:tzif", "std", "dep:jiff-tzdb", "dep:combine"]
 std = []

docs/TZDB.md

@@ -67,3 +67,34 @@ Range: Seconds(36000)..Seconds(39600)
 Diff value: Seconds(37800)
 Contains Result: true
 Result: [LocalTimeTypeRecord { utoff: Seconds(39600), is_dst: true, idx: 4 }, LocalTimeTypeRecord { utoff: Seconds(36000), is_dst: false, idx: 9 }]
+
+## Slim format testing
+
+`jiff_tzdb` and potentially others use a different compiled `tzif`
+than operating systems.
+
+Where operating systems use the "-b fat", smaller embedded tzifs may
+use "-b slim" (it's also worth noting that slim is the default setting)
+
+What does slim actually do? The slim formats "slims" the size of a tzif
+by calculating the transition times for a smaller range. Instead of calculating
+the transition times in a larger range, the tzif (and thus user) differs to
+the POSIX tz string.
+
+So in order to support "slim" format `tzif`s, we need to be able to resolve the
+[POSIX tz string](glibc-posix-docs).
+
+### Running tests / logging
+
+While using `jiff_tzdb`, the binary search will run the below:
+
+Running a date from 2017 using jiff:
+
+time array length: 175
+Returned idx: Err(175)
+
+This will panic, because we have gone past the supported transition times, so
+we should default to parsing the POSIX tz string.
+
+
+[glibc-posix-docs]:https://sourceware.org/glibc/manual/2.40/html_node/Proleptic-TZ.html

src/components/tz.rs

@@ -9,12 +9,12 @@ use num_traits::ToPrimitive;
 
 use crate::{components::Instant, iso::IsoDateTime, TemporalError, TemporalResult};
 
-#[cfg(all(feature = "tzdb", not(target_os = "windows")))]
+#[cfg(feature = "experimental")]
 use crate::tzdb::FsTzdbProvider;
-#[cfg(all(feature = "experimental", not(target_os = "windows")))]
+#[cfg(feature = "experimental")]
 use std::sync::{LazyLock, Mutex};
 
-#[cfg(all(feature = "experimental", not(target_os = "windows")))]
+#[cfg(feature = "experimental")]
 pub static TZ_PROVIDER: LazyLock<Mutex<FsTzdbProvider>> =
     LazyLock::new(|| Mutex::new(FsTzdbProvider::default()));
 

src/components/zoneddatetime.rs

@@ -9,9 +9,9 @@ use crate::{
 
 use super::{calendar::CalendarDateLike, tz::TzProvider, PlainDateTime};
 
-#[cfg(all(feature = "experimental", not(target_os = "windows")))]
+#[cfg(feature = "experimental")]
 use crate::{components::tz::TZ_PROVIDER, TemporalError};
-#[cfg(all(feature = "experimental", not(target_os = "windows")))]
+#[cfg(feature = "experimental")]
 use std::ops::DerefMut;
 
 /// The native Rust implementation of `Temporal.ZonedDateTime`.
@@ -101,7 +101,7 @@ impl ZonedDateTime {
 
 // ===== TzProvider APIs for ZonedDateTime =====
 
-#[cfg(all(feature = "experimental", not(target_os = "windows")))]
+#[cfg(feature = "experimental")]
 impl ZonedDateTime {
     pub fn year(&self) -> TemporalResult<i32> {
         let mut provider = TZ_PROVIDER
@@ -223,7 +223,7 @@ impl ZonedDateTime {
     }
 }
 
-#[cfg(all(feature = "tzdb", not(target_os = "windows")))]
+#[cfg(feature = "tzdb")]
 #[cfg(test)]
 mod tests {
 

src/lib.rs

@@ -58,7 +58,7 @@ pub(crate) mod iso;
 #[cfg(feature = "std")]
 mod sys;
 
-#[cfg(all(feature = "tzdb", not(target_os = "windows")))]
+#[cfg(feature = "tzdb")]
 pub mod tzdb;
 
 #[doc(hidden)]