Add DebugStructExt helper for writing less verbose Debug impls

Author: jplatte

crates/matrix-sdk-common/src/debug.rs

@@ -18,6 +18,28 @@ use std::fmt;
 
 use ruma::serde::Raw;
 
+pub trait DebugStructExt<'a, 'b> {
+    fn maybe_field<T: fmt::Debug>(
+        &mut self,
+        name: &str,
+        value: &Option<T>,
+    ) -> &mut fmt::DebugStruct<'a, 'b>;
+}
+
+impl<'a, 'b> DebugStructExt<'a, 'b> for fmt::DebugStruct<'a, 'b> {
+    fn maybe_field<T: fmt::Debug>(
+        &mut self,
+        name: &str,
+        value: &Option<T>,
+    ) -> &mut fmt::DebugStruct<'a, 'b> {
+        if let Some(value) = value {
+            self.field(name, value);
+        }
+
+        self
+    }
+}
+
 /// A wrapper around `Raw` that implements `Debug` in a way that only prints the
 /// event ID and event type.
 pub struct DebugRawEvent<'a, T>(pub &'a Raw<T>);

crates/matrix-sdk/src/config/sync.rs

@@ -14,6 +14,7 @@
 
 use std::{fmt, time::Duration};
 
+use matrix_sdk_common::debug::DebugStructExt;
 use ruma::{api::client::sync::sync_events, presence::PresenceState};
 
 const DEFAULT_SYNC_TIMEOUT: Duration = Duration::from_secs(30);
@@ -38,20 +39,13 @@ impl Default for SyncSettings {
 #[cfg(not(tarpaulin_include))]
 impl fmt::Debug for SyncSettings {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        let mut s = f.debug_struct("SyncSettings");
-
-        macro_rules! opt_field {
-            ($field:ident) => {
-                if let Some(value) = &self.$field {
-                    s.field(stringify!($field), value);
-                }
-            };
-        }
-
-        opt_field!(filter);
-        opt_field!(timeout);
-
-        s.field("full_state", &self.full_state).finish()
+        let Self { filter, timeout, token: _, full_state, set_presence } = self;
+        f.debug_struct("SyncSettings")
+            .maybe_field("filter", filter)
+            .maybe_field("timeout", timeout)
+            .field("full_state", full_state)
+            .field("set_presence", set_presence)
+            .finish()
     }
 }