refactor: replace unwrap_or with unwrap_or_else for improved error handling (#5163)

In Rust, the `or` and `or_else` methods have distinct behavioral differences. The `or` method always eagerly evaluates its argument and executes any associated function calls. This can lead to unnecessary performance costs—especially in expensive operations like string processing or file handling—and may even trigger unintended side effects.

In contrast, `or_else` evaluates its closure lazily, only when necessary. Introducing a Clippy lint to disallow `or` sacrifices a bit of code simplicity but ensures predictable behavior and enforces lazy evaluation for better performance.

src-tauri/src/utils/dirs.rs

@@ -47,7 +47,7 @@ pub fn app_home_dir() -> Result<PathBuf> {
         let app_exe = dunce::canonicalize(app_exe)?;
         let app_dir = app_exe
             .parent()
-            .ok_or(anyhow::anyhow!("failed to get the portable app dir"))?;
+            .ok_or_else(|| anyhow::anyhow!("failed to get the portable app dir"))?;
         return Ok(PathBuf::from(app_dir).join(".config").join(APP_ID));
     }
 
@@ -170,7 +170,7 @@ pub fn path_to_str(path: &PathBuf) -> Result<&str> {
     let path_str = path
         .as_os_str()
         .to_str()
-        .ok_or(anyhow::anyhow!("failed to get path from {:?}", path))?;
+        .ok_or_else(|| anyhow::anyhow!("failed to get path from {:?}", path))?;
     Ok(path_str)
 }
 

src-tauri/src/utils/help.rs

@@ -34,10 +34,9 @@ pub async fn read_mapping(path: &PathBuf) -> Result<Mapping> {
 
             Ok(val
                 .as_mapping()
-                .ok_or(anyhow!(
-                    "failed to transform to yaml mapping \"{}\"",
-                    path.display()
-                ))?
+                .ok_or_else(|| {
+                    anyhow!("failed to transform to yaml mapping \"{}\"", path.display())
+                })?
                 .to_owned())
         }
         Err(err) => {

src-tauri/src/utils/init.rs

@@ -155,9 +155,9 @@ pub async fn delete_log() -> Result<()> {
         let month = u32::from_str(sa[1])?;
         let day = u32::from_str(sa[2])?;
         let time = chrono::NaiveDate::from_ymd_opt(year, month, day)
-            .ok_or(anyhow::anyhow!("invalid time str"))?
+            .ok_or_else(|| anyhow::anyhow!("invalid time str"))?
             .and_hms_opt(0, 0, 0)
-            .ok_or(anyhow::anyhow!("invalid time str"))?;
+            .ok_or_else(|| anyhow::anyhow!("invalid time str"))?;
         Ok(time)
     };
 
@@ -171,7 +171,7 @@ pub async fn delete_log() -> Result<()> {
             let file_time = Local
                 .from_local_datetime(&created_time)
                 .single()
-                .ok_or(anyhow::anyhow!("invalid local datetime"))?;
+                .ok_or_else(|| anyhow::anyhow!("invalid local datetime"))?;
 
             let duration = now.signed_duration_since(file_time);
             if duration.num_days() > day {
@@ -523,7 +523,7 @@ pub async fn startup_script() -> Result<()> {
     let script_path = {
         let verge = Config::verge().await;
         let verge = verge.latest_ref();
-        verge.startup_script.clone().unwrap_or("".into())
+        verge.startup_script.clone().unwrap_or_else(|| "".into())
     };
 
     if script_path.is_empty() {
@@ -547,7 +547,7 @@ pub async fn startup_script() -> Result<()> {
     }
 
     let parent_dir = script_dir.parent();
-    let working_dir = parent_dir.unwrap_or(script_dir.as_ref());
+    let working_dir = parent_dir.unwrap_or_else(|| script_dir.as_ref());
 
     app_handle
         .shell()

src-tauri/src/utils/resolve/window.rs

@@ -26,7 +26,7 @@ pub async fn build_new_window() -> Result<WebviewWindow, String> {
         .latest_ref()
         .start_page
         .clone()
-        .unwrap_or("/".into());
+        .unwrap_or_else(|| "/".into());
     match tauri::WebviewWindowBuilder::new(
         app_handle,
         "main", /* the unique window label */

src-tauri/src/utils/server.rs

@@ -88,12 +88,12 @@ pub fn embed_server() {
             .latest_ref()
             .pac_file_content
             .clone()
-            .unwrap_or(DEFAULT_PAC.into());
+            .unwrap_or_else(|| DEFAULT_PAC.into());
 
         let pac_port = verge_config
             .latest_ref()
             .verge_mixed_port
-            .unwrap_or(clash_config.latest_ref().get_mixed_port());
+            .unwrap_or_else(|| clash_config.latest_ref().get_mixed_port());
 
         let pac = warp::path!("commands" / "pac").map(move || {
             let processed_content = pac_content.replace("%mixed-port%", &format!("{pac_port}"));