Add feature gated defmt support.

Author: pebender

chrono-tz-build/src/lib.rs

@@ -140,6 +140,10 @@ fn write_timezone_file(timezone_file: &mut File, table: &Table, uncased: bool) -
         )?;
     }
 
+    writeln!(
+        timezone_file,
+        "#[cfg_attr(feature = \"defmt\", derive(defmt::Format))]"
+    )?;
     writeln!(
         timezone_file,
         r#"#[derive(Copy, Clone, Debug, PartialEq, Eq)]
@@ -208,6 +212,16 @@ impl FromStr for Tz {{
         f.write_str(self.name().as_ref())
     }}
 }}\n"
+    )?;
+    writeln!(
+        timezone_file,
+        r#"#[cfg(feature = "defmt")]
+impl defmt::Format for Tz {{
+    fn format(&self, f: defmt::Formatter) {{
+        defmt::write!(f, "{{:?}}", self.name());
+    }}
+}}
+"#
     )?;
     writeln!(
         timezone_file,

chrono-tz/Cargo.toml

@@ -32,13 +32,15 @@ include = [
 [dependencies]
 arbitrary = { version = "1.2", optional = true, features = ["derive"] }
 chrono = { version = "0.4.25", default-features = false }
+defmt = { version = "1.0.1", optional = true }
 serde_core = { version = "1.0.220", optional = true, default-features = false }
 phf = { version = "0.13", default-features = false }
 uncased = { version = "0.9", optional = true, default-features = false }
 
 [features]
 default = ["std"]
 std = []
+defmt = ["dep:defmt"]
 serde = ["dep:serde_core"]
 filter-by-regex = ["chrono-tz-build", "chrono-tz-build/filter-by-regex"]
 case-insensitive = ["dep:uncased", "chrono-tz-build", "chrono-tz-build/case-insensitive", "phf/uncased"]

chrono-tz/src/prebuilt/timezones.rs

@@ -1931,6 +1931,7 @@ static TIMEZONES: ::phf::Map<&'static str, Tz> =
         ("Asia/Harbin", Tz::Asia__Harbin),
     ],
 };
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 pub struct ParseError(());
 
@@ -2565,6 +2566,13 @@ impl Display for Tz {
     }
 }
 
+#[cfg(feature = "defmt")]
+impl defmt::Format for Tz {
+    fn format(&self, f: defmt::Formatter) {
+        defmt::write!(f, "{:?}", self.name());
+    }
+}
+
 impl TimeSpans for Tz {
     fn timespans(&self) -> FixedTimespanSet {
         const AFRICA__ABIDJAN: FixedTimespanSet = FixedTimespanSet {

chrono-tz/src/timezone_impl.rs

@@ -32,6 +32,13 @@ impl Debug for FixedTimespan {
     }
 }
 
+#[cfg(feature = "defmt")]
+impl defmt::Format for FixedTimespan {
+    fn format(&self, f: defmt::Formatter) {
+        defmt::write!(f, "{:?}", self.name);
+    }
+}
+
 #[derive(Copy, Clone, PartialEq, Eq)]
 pub struct TzOffset {
     tz: Tz,
@@ -118,6 +125,13 @@ impl Debug for TzOffset {
     }
 }
 
+#[cfg(feature = "defmt")]
+impl defmt::Format for TzOffset {
+    fn format(&self, f: defmt::Formatter) {
+        defmt::write!(f, "{:?}", self.offset);
+    }
+}
+
 /// Represents the span of time that a given rule is valid for.
 /// Note that I have made the assumption that all ranges are
 /// left-inclusive and right-exclusive - that is to say,