Use strum to iterate through enum variants and get their names (#35933)

`strum` allows us to avoid manually listing enum variant names and also
to get their names as static strings. We cannot use this for all cases
due to https://github.com/Peternator7/strum/issues/152, but we can
still use it to remove a lot of code.

Signed-off-by: Martin Robinson <mrobinson@igalia.com>

components/shared/compositing/Cargo.toml

@@ -22,6 +22,7 @@ log = { workspace = true }
 pixels = { path = '../../pixels' }
 script_traits = { workspace = true }
 servo_url = { path = "../../url" }
+strum_macros = { workspace = true }
 style_traits = { workspace = true }
 webrender_api = { workspace = true }
 webrender_traits = { workspace = true }

components/shared/compositing/constellation_msg.rs

@@ -14,9 +14,11 @@ use embedder_traits::{
 use ipc_channel::ipc::IpcSender;
 use script_traits::{AnimationTickType, LogEntry, WindowSizeData, WindowSizeType};
 use servo_url::ServoUrl;
+use strum_macros::IntoStaticStr;
 use webrender_traits::CompositorHitTestResult;
 
 /// Messages to the constellation.
+#[derive(IntoStaticStr)]
 pub enum ConstellationMsg {
     /// Exit the constellation.
     Exit,
@@ -77,41 +79,7 @@ pub enum ConstellationMsg {
 
 impl fmt::Debug for ConstellationMsg {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-        write!(formatter, "ConstellationMsg::{}", self.variant_name())
-    }
-}
-
-impl ConstellationMsg {
-    /// Return the variant name, for error logging that happens after the message is consumed.
-    pub fn variant_name(&self) -> &'static str {
-        use self::ConstellationMsg::*;
-        match *self {
-            Exit => "Exit",
-            GetBrowsingContext(..) => "GetBrowsingContext",
-            GetPipeline(..) => "GetPipeline",
-            GetFocusTopLevelBrowsingContext(..) => "GetFocusTopLevelBrowsingContext",
-            IsReadyToSaveImage(..) => "IsReadyToSaveImage",
-            AllowNavigationResponse(..) => "AllowNavigationResponse",
-            LoadUrl(..) => "LoadUrl",
-            TraverseHistory(..) => "TraverseHistory",
-            WindowSize(..) => "WindowSize",
-            ThemeChange(..) => "ThemeChange",
-            TickAnimation(..) => "TickAnimation",
-            WebDriverCommand(..) => "WebDriverCommand",
-            Reload(..) => "Reload",
-            LogEntry(..) => "LogEntry",
-            NewWebView(..) => "NewWebView",
-            CloseWebView(..) => "CloseWebView",
-            FocusWebView(..) => "FocusWebView",
-            BlurWebView => "BlurWebView",
-            SendError(..) => "SendError",
-            ForwardInputEvent(..) => "ForwardEvent",
-            SetCursor(..) => "SetCursor",
-            ToggleProfiler(..) => "EnableProfiler",
-            ExitFullScreen(..) => "ExitFullScreen",
-            MediaSessionAction(..) => "MediaSessionAction",
-            SetWebViewThrottled(..) => "SetWebViewThrottled",
-            ClearCache => "ClearCache",
-        }
+        let variant_string: &'static str = self.into();
+        write!(formatter, "ConstellationMsg::{variant_string}")
     }
 }

components/shared/compositing/lib.rs

@@ -18,6 +18,7 @@ use ipc_channel::ipc::IpcSender;
 use log::warn;
 use pixels::Image;
 use script_traits::{AnimationState, ScriptThreadMessage, TouchEventResult};
+use strum_macros::IntoStaticStr;
 use style_traits::CSSPixel;
 use webrender_api::DocumentId;
 use webrender_traits::{CrossProcessCompositorApi, CrossProcessCompositorMessage};
@@ -57,6 +58,7 @@ impl CompositorReceiver {
 }
 
 /// Messages from (or via) the constellation thread to the compositor.
+#[derive(IntoStaticStr)]
 pub enum CompositorMsg {
     /// Alerts the compositor that the given pipeline has changed whether it is running animations.
     ChangeRunningAnimationsState(WebViewId, PipelineId, AnimationState),
@@ -112,24 +114,8 @@ pub struct CompositionPipeline {
 }
 
 impl Debug for CompositorMsg {
-    fn fmt(&self, f: &mut Formatter) -> Result<(), Error> {
-        match *self {
-            CompositorMsg::ChangeRunningAnimationsState(_, _, state) => {
-                write!(f, "ChangeRunningAnimationsState({:?})", state)
-            },
-            CompositorMsg::CreateOrUpdateWebView(..) => write!(f, "CreateOrUpdateWebView"),
-            CompositorMsg::RemoveWebView(..) => write!(f, "RemoveWebView"),
-            CompositorMsg::TouchEventProcessed(..) => write!(f, "TouchEventProcessed"),
-            CompositorMsg::CreatePng(..) => write!(f, "CreatePng"),
-            CompositorMsg::IsReadyToSaveImageReply(..) => write!(f, "IsReadyToSaveImageReply"),
-            CompositorMsg::SetThrottled(..) => write!(f, "SetThrottled"),
-            CompositorMsg::PipelineExited(..) => write!(f, "PipelineExited"),
-            CompositorMsg::NewWebRenderFrameReady(..) => write!(f, "NewWebRenderFrameReady"),
-            CompositorMsg::PendingPaintMetric(..) => write!(f, "PendingPaintMetric"),
-            CompositorMsg::LoadComplete(..) => write!(f, "LoadComplete"),
-            CompositorMsg::WebDriverMouseButtonEvent(..) => write!(f, "WebDriverMouseButtonEvent"),
-            CompositorMsg::WebDriverMouseMoveEvent(..) => write!(f, "WebDriverMouseMoveEvent"),
-            CompositorMsg::CrossProcess(..) => write!(f, "CrossProcess"),
-        }
+    fn fmt(&self, formatter: &mut Formatter) -> Result<(), Error> {
+        let string: &'static str = self.into();
+        write!(formatter, "{string}")
     }
 }