Add impls for Chrono structs

CHANGELOG.md

@@ -7,6 +7,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
+- [#893]: Add impls for structs in Chrono crate
 - [#889]: Add script for book hosting
 - [#887]: Fix interning example in the book
 - [#884]: Upgrade dependencies: notify is now at v7, thiserror is now at v2 

defmt/Cargo.toml

@@ -20,6 +20,7 @@ version = "0.3.8"
 [features]
 alloc = []
 avoid-default-panic = []
+chrono = []
 ip_in_core = []
 
 # Encoding feature flags. These should only be set by end-user crates, not by library crates.
@@ -45,6 +46,7 @@ unstable-test = [ "defmt-macros/unstable-test" ]
 [dependencies]
 defmt-macros = { path = "../macros", version = "0.3.2" }
 bitflags = "1"
+chrono = "0.4.38"
 
 [dev-dependencies]
 rustc_version = "0.4"

defmt/src/impls/core_/chrono.rs

@@ -0,0 +1,77 @@
+use super::*;
+extern crate chrono;
+use chrono::{
+    DateTime, Datelike, FixedOffset, Months, NaiveDate, NaiveDateTime, NaiveTime, OutOfRange,
+    TimeDelta, TimeZone, Timelike, Utc,
+};
+
+impl<Tz: TimeZone> Format for DateTime<Tz> {
+    fn format(&self, fmt: Formatter) {
+        crate::write!(
+            fmt,
+            "{:04}-{:02}-{:02}",
+            self.year(),
+            self.month(),
+            self.day()
+        );
+    }
+}
+
+impl Format for FixedOffset {
+    fn format(&self, fmt: Formatter) {
+        crate::write!(fmt, "FixedOffset({})", self.local_minus_utc());
+    }
+}
+
+impl Format for Months {
+    fn format(&self, fmt: Formatter) {
+        crate::write!(fmt, "Months({=u32})", self.as_u32());
+    }
+}
+
+impl Format for NaiveDate {
+    fn format(&self, fmt: Formatter) {
+        crate::write!(
+            fmt,
+            "{:04}-{:02}-{:02}",
+            self.year(),
+            self.month(),
+            self.day()
+        );
+    }
+}
+
+impl Format for NaiveDateTime {
+    fn format(&self, fmt: Formatter) {
+        crate::write!(fmt, "{}T{}", self.date(), self.time());
+    }
+}
+
+impl Format for NaiveTime {
+    fn format(&self, fmt: Formatter) {
+        crate::write!(fmt, "{}:{}:{}", self.hour(), self.minute(), self.second());
+    }
+}
+
+impl Format for OutOfRange {
+    fn format(&self, fmt: Formatter) {
+        crate::write!(fmt, "out of range");
+    }
+}
+
+impl Format for TimeDelta {
+    fn format(&self, fmt: Formatter) {
+        crate::write!(
+            fmt,
+            "TimeDelta {{ secs: {=i64}, nanos: {=i32} }}",
+            self.num_seconds(),
+            self.subsec_nanos()
+        );
+    }
+}
+
+impl Format for Utc {
+    fn format(&self, fmt: Formatter) {
+        crate::write!(fmt, "UTC");
+    }
+}

defmt/src/impls/core_/mod.rs

@@ -8,6 +8,8 @@
 mod alloc_;
 mod array;
 mod cell;
+#[cfg(feature = "chrono")]
+mod chrono;
 #[cfg(feature = "ip_in_core")]
 mod net;
 mod num;