derive 'Default' where possible

crates/tor-netdoc/src/doc/microdesc.rs

@@ -39,7 +39,7 @@ pub use build::MicrodescBuilder;
 /// Annotations prepended to a microdescriptor that has been stored to
 /// disk.
 #[allow(dead_code)]
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, Default)]
 pub struct MicrodescAnnotation {
     /// A time at which this microdescriptor was last listed in some
     /// consensus document.
@@ -193,12 +193,6 @@ static MICRODESC_RULES: Lazy<SectionRules<MicrodescKwd>> = Lazy::new(|| {
     rules
 });
 
-impl Default for MicrodescAnnotation {
-    fn default() -> Self {
-        MicrodescAnnotation { last_listed: None }
-    }
-}
-
 impl MicrodescAnnotation {
     /// Extract a (possibly empty) microdescriptor annotation from a
     /// reader.

crates/tor-netdoc/src/doc/routerdesc.rs

@@ -60,6 +60,7 @@ pub struct AnnotatedRouterDesc {
 
 /// Annotations about a router descriptor, as stored on disc.
 #[allow(dead_code)] // don't warn about fields not getting read.
+#[derive(Default)]
 pub struct RouterAnnotation {
     /// Description of where we got this router descriptor
     source: Option<String>,
@@ -284,16 +285,6 @@ static ROUTER_SIG_RULES: Lazy<SectionRules<RouterKwd>> = Lazy::new(|| {
     rules
 });
 
-impl Default for RouterAnnotation {
-    fn default() -> Self {
-        RouterAnnotation {
-            source: None,
-            downloaded: None,
-            purpose: None,
-        }
-    }
-}
-
 impl RouterAnnotation {
     /// Extract a single RouterAnnotation (possibly empty) from a reader.
     fn take_from_reader(reader: &mut NetDocReader<'_, RouterKwd>) -> Result<RouterAnnotation> {