Fix easy clippy lints from latest stable (#16053)

1.88.0 was released today, clippy now lints (machine-applicable)
against:
- format strings with empty braces that could be inlined
  - easy win
- `manual_abs_diff`
- returning of a stored result of the last expression.
  - this can be somewhat contentious but touched only a few places

crates/nu-cli/src/completions/cell_path_completions.rs

@@ -118,7 +118,7 @@ fn get_suggestions_by_value(
             || s.chars()
                 .any(|c: char| !(c.is_ascii_alphabetic() || ['_', '-'].contains(&c)))
         {
-            format!("{:?}", s)
+            format!("{s:?}")
         } else {
             s
         };

crates/nu-cli/src/completions/command_completions.rs

@@ -52,7 +52,7 @@ impl CommandCompletion {
                                 continue;
                             };
                             let value = if matched_internal(&name) {
-                                format!("^{}", name)
+                                format!("^{name}")
                             } else {
                                 name.clone()
                             };

crates/nu-cli/src/completions/completer.rs

@@ -176,7 +176,7 @@ impl NuCompleter {
             &mut working_set,
             Some("completer"),
             // Add a placeholder `a` to the end
-            format!("{}a", line).as_bytes(),
+            format!("{line}a").as_bytes(),
             false,
         );
         self.fetch_completions_by_block(block, &working_set, pos, offset, line, true)
@@ -850,7 +850,7 @@ mod completer_tests {
         for (line, has_result, begins_with, expected_values) in dataset {
             let result = completer.fetch_completions_at(line, line.len());
             // Test whether the result is empty or not
-            assert_eq!(!result.is_empty(), has_result, "line: {}", line);
+            assert_eq!(!result.is_empty(), has_result, "line: {line}");
 
             // Test whether the result begins with the expected value
             result
@@ -865,8 +865,7 @@ mod completer_tests {
                     .filter(|x| *x)
                     .count(),
                 expected_values.len(),
-                "line: {}",
-                line
+                "line: {line}"
             );
         }
     }

crates/nu-cli/src/completions/completion_common.rs

@@ -314,7 +314,7 @@ pub fn escape_path(path: String) -> String {
         if path.contains('\'') {
             // decide to use double quotes
             // Path as Debug will do the escaping for `"`, `\`
-            format!("{:?}", path)
+            format!("{path:?}")
         } else {
             format!("'{path}'")
         }

crates/nu-cli/src/completions/dotnu_completions.rs

@@ -129,7 +129,7 @@ impl Completer for DotNuCompletion {
                     .take_while(|c| "`'\"".contains(*c))
                     .collect::<String>();
                 for path in ["std", "std-rfc"] {
-                    let path = format!("{}{}", surround_prefix, path);
+                    let path = format!("{surround_prefix}{path}");
                     matcher.add(
                         path.clone(),
                         FileSuggestion {
@@ -146,7 +146,7 @@ impl Completer for DotNuCompletion {
                 for sub_vp_id in sub_paths {
                     let (path, sub_vp) = working_set.get_virtual_path(*sub_vp_id);
                     let path = path
-                        .strip_prefix(&format!("{}/", base_dir))
+                        .strip_prefix(&format!("{base_dir}/"))
                         .unwrap_or(path)
                         .to_string();
                     matcher.add(

crates/nu-cli/src/repl.rs

@@ -239,7 +239,7 @@ fn escape_special_vscode_bytes(input: &str) -> Result<String, ShellError> {
 
                 match byte {
                     // Escape bytes below 0x20
-                    b if b < 0x20 => format!("\\x{:02X}", byte).into_bytes(),
+                    b if b < 0x20 => format!("\\x{byte:02X}").into_bytes(),
                     // Escape semicolon as \x3B
                     b';' => "\\x3B".to_string().into_bytes(),
                     // Escape backslash as \\
@@ -1097,8 +1097,7 @@ fn run_shell_integration_osc633(
             // If we're in vscode, run their specific ansi escape sequence.
             // This is helpful for ctrl+g to change directories in the terminal.
             run_ansi_sequence(&format!(
-                "{}{}{}",
-                VSCODE_CWD_PROPERTY_MARKER_PREFIX, path, VSCODE_CWD_PROPERTY_MARKER_SUFFIX
+                "{VSCODE_CWD_PROPERTY_MARKER_PREFIX}{path}{VSCODE_CWD_PROPERTY_MARKER_SUFFIX}"
             ));
 
             perf!(
@@ -1114,10 +1113,7 @@ fn run_shell_integration_osc633(
 
             //OSC 633 ; E ; <commandline> [; <nonce] ST - Explicitly set the command line with an optional nonce.
             run_ansi_sequence(&format!(
-                "{}{}{}",
-                VSCODE_COMMANDLINE_MARKER_PREFIX,
-                replaced_cmd_text,
-                VSCODE_COMMANDLINE_MARKER_SUFFIX
+                "{VSCODE_COMMANDLINE_MARKER_PREFIX}{replaced_cmd_text}{VSCODE_COMMANDLINE_MARKER_SUFFIX}"
             ));
         }
     }
@@ -1493,7 +1489,7 @@ mod test_auto_cd {
         // Parse the input. It must be an auto-cd operation.
         let op = parse_operation(input.to_string(), &engine_state, &stack).unwrap();
         let ReplOperation::AutoCd { cwd, target, span } = op else {
-            panic!("'{}' was not parsed into an auto-cd operation", input)
+            panic!("'{input}' was not parsed into an auto-cd operation")
         };
 
         // Perform the auto-cd operation.