Fallable constructors for less panics (#815)

Cargo.toml

@@ -20,6 +20,7 @@ default = ["clock", "std", "wasmbind"]
 alloc = []
 libc = []
 std = []
+serde = ["dep:serde", "dep:serde_json"]
 clock = ["std", "windows-sys", "iana-time-zone"]
 wasmbind = ["wasm-bindgen", "js-sys"]
 unstable-locales = ["pure-rust-locales", "alloc"]
@@ -28,6 +29,7 @@ __doctest = []
 
 [dependencies]
 serde = { version = "1.0.99", default-features = false, optional = true }
+serde_json = { version = "1", optional = true}
 pure-rust-locales = { version = "0.5.2", optional = true }
 criterion = { version = "0.4.0", optional = true }
 rkyv = {version = "0.7", optional = true}
@@ -44,7 +46,6 @@ windows-sys = { version = "0.48.0", features = ["Win32_System_Time", "Win32_Foun
 iana-time-zone = { version = "0.1.45", optional = true, features = ["fallback"] }
 
 [dev-dependencies]
-serde_json = { version = "1" }
 serde_derive = { version = "1", default-features = false }
 bincode = { version = "1.3.0" }
 num-iter = { version = "0.1.35", default-features = false }

README.md

@@ -47,9 +47,9 @@ Consider using `NaiveDateTime` with the implicit TAI (International Atomic Time)
 if you want.
 
 Chrono inherently does not support an inaccurate or partial date and time representation.
-Any operation that can be ambiguous will return `None` in such cases.
+Any operation that can be ambiguous will return `Err(chrono::Error)` in such cases.
 For example, "a month later" of 2014-01-30 is not well-defined
-and consequently `Utc.ymd_opt(2014, 1, 30).unwrap().with_month(2)` returns `None`.
+and consequently `NaiveDate::from_ymd(2014, 1, 30)?.with_month(2)` returns `Err(chrono::Error)`.
 
 Non ISO week handling is not yet supported.
 For now you can use the [chrono_ext](https://crates.io/crates/chrono_ext)

benches/chrono.rs

@@ -35,28 +35,18 @@ fn bench_datetime_from_str(c: &mut Criterion) {
 }
 
 fn bench_datetime_to_rfc2822(c: &mut Criterion) {
-    let pst = FixedOffset::east_opt(8 * 60 * 60).unwrap();
-    let dt = pst
-        .from_local_datetime(
-            &NaiveDate::from_ymd_opt(2018, 1, 11)
-                .unwrap()
-                .and_hms_nano_opt(10, 5, 13, 84_660_000)
-                .unwrap(),
-        )
-        .unwrap();
+    let pst = FixedOffset::east(8 * 60 * 60).unwrap();
+    let dt = pst.from_local_datetime(
+        &NaiveDate::from_ymd(2018, 1, 11)?.and_hms_nano(10, 5, 13, 84_660_000)?,
+    );
     c.bench_function("bench_datetime_to_rfc2822", |b| b.iter(|| black_box(dt).to_rfc2822()));
 }
 
 fn bench_datetime_to_rfc3339(c: &mut Criterion) {
-    let pst = FixedOffset::east_opt(8 * 60 * 60).unwrap();
-    let dt = pst
-        .from_local_datetime(
-            &NaiveDate::from_ymd_opt(2018, 1, 11)
-                .unwrap()
-                .and_hms_nano_opt(10, 5, 13, 84_660_000)
-                .unwrap(),
-        )
-        .unwrap();
+    let pst = FixedOffset::east(8 * 60 * 60).unwrap();
+    let dt = pst.from_local_datetime(
+        &NaiveDate::from_ymd(2018, 1, 11)?.and_hms_nano(10, 5, 13, 84_660_000)?,
+    );
     c.bench_function("bench_datetime_to_rfc3339", |b| b.iter(|| black_box(dt).to_rfc3339()));
 }
 
@@ -112,7 +102,7 @@ fn num_days_from_ce_alt<Date: Datelike>(date: &Date) -> i32 {
 fn bench_num_days_from_ce(c: &mut Criterion) {
     let mut group = c.benchmark_group("num_days_from_ce");
     for year in &[1, 500, 2000, 2019] {
-        let d = NaiveDate::from_ymd_opt(*year, 1, 1).unwrap();
+        let d = NaiveDate::from_ymd(*year, 1, 1).unwrap();
         group.bench_with_input(BenchmarkId::new("new", year), &d, |b, y| {
             b.iter(|| num_days_from_ce_alt(y))
         });

ci/core-test/src/lib.rs

@@ -2,6 +2,7 @@
 
 use chrono::{TimeZone, Utc};
 
-pub fn create_time() {
-    let _ = Utc.with_ymd_and_hms(2019, 1, 1, 0, 0, 0).unwrap();
+pub fn create_time() -> Result<(), chrono::Error> {
+    let _ = Utc.with_ymd_and_hms(2019, 1, 1, 0, 0, 0)?.single()?;
+    Ok(())
 }