fix: clippy warnings

Author: mtshiba

crates/els/completion.rs

@@ -255,7 +255,10 @@ fn module_item(name: &str, mistype: bool, insert: Option<u32>) -> CompletionItem
     // => `datetime = pyimport "datetime"`
     if let Some(line) = insert {
         let prefix = if mistype { "py" } else { "" };
-        let import = format!("{} = {prefix}", name.split('/').last().unwrap_or("module"));
+        let import = format!(
+            "{} = {prefix}",
+            name.split('/').next_back().unwrap_or("module")
+        );
         item.additional_text_edits = Some(vec![TextEdit {
             range: Range::new(Position::new(line - 1, 0), Position::new(line - 1, 0)),
             new_text: import,

crates/els/hir_visitor.rs

@@ -107,7 +107,7 @@ impl<'a> HIRVisitor<'a> {
             .uri
             .path()
             .split('/')
-            .last()
+            .next_back()
             .unwrap_or_default()
             .split('.')
             .next()

crates/erg_common/io.rs

@@ -394,7 +394,7 @@ impl Input {
         dir.set_extension("er"); // {path/to}.er
         let path = dir.canonicalize().or_else(|_| {
             dir.pop(); // {path}
-            dir.push(path.iter().last().unwrap_or_default()); // {path/to}
+            dir.push(path.iter().next_back().unwrap_or_default()); // {path/to}
             dir.push("__init__.er"); // -> {path/to}/__init__.er
             dir.canonicalize()
         })?;

crates/erg_common/pathutil.rs

@@ -287,7 +287,7 @@ pub fn mod_name(path: &Path) -> Str {
                 .next()
                 .unwrap()
                 .split('/')
-                .last()
+                .next_back()
                 .unwrap();
             let sub = path
                 .split("/src/")

crates/erg_compiler/module/promise.rs

@@ -242,7 +242,7 @@ impl SharedPromises {
         for promise in self.promises.borrow().values() {
             match promise {
                 Promise::Running { .. } => running += 1,
-                Promise::Joined { .. } => finished += 1,
+                Promise::Joined => finished += 1,
             }
             total += 1;
         }

crates/erg_compiler/ty/mod.rs

@@ -1728,7 +1728,7 @@ impl LimitedDisplay for Type {
                         name.trim_matches('\"')
                             .trim_end_matches('/')
                             .split('/')
-                            .last()
+                            .next_back()
                             .unwrap()
                     )?;
                     return Ok(());

crates/erg_compiler/ty/value.rs

@@ -1402,7 +1402,8 @@ impl ValueObj {
                     }
                     if content.len() >= 3 && content.get(content.len() - 3..) == Some("\"\"\"") {
                         content = Str::rc(&content[..content.len() - 3]);
-                    } else if content.len() >= 1 && content.get(content.len() - 1..) == Some("\"") {
+                    } else if !content.is_empty() && content.get(content.len() - 1..) == Some("\"")
+                    {
                         content = Str::rc(&content[..content.len() - 1]);
                     }
                     Some(Self::Str(content))