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-parser/src/parse_keywords.rs

@@ -2160,12 +2160,10 @@ fn module_needs_reloading(working_set: &StateWorkingSet, module_id: ModuleId) ->
         return true;
     }
 
-    let private_submodule_changed = module
+    module
         .imported_modules
         .iter()
-        .any(|submodule_id| submodule_need_reloading(working_set, *submodule_id));
-
-    private_submodule_changed
+        .any(|submodule_id| submodule_need_reloading(working_set, *submodule_id))
 }
 
 /// Parse a module from a file.
@@ -4052,7 +4050,7 @@ pub fn parse_plugin_use(working_set: &mut StateWorkingSet, call: Box<Call>) -> P
 
 pub fn find_dirs_var(working_set: &StateWorkingSet, var_name: &str) -> Option<VarId> {
     working_set
-        .find_variable(format!("${}", var_name).as_bytes())
+        .find_variable(format!("${var_name}").as_bytes())
         .filter(|var_id| working_set.get_variable(*var_id).const_val.is_some())
 }
 

crates/nu-parser/src/parse_shape_specs.rs

@@ -37,7 +37,7 @@ pub fn parse_shape_name(
     span: Span,
     use_loc: ShapeDescriptorUse,
 ) -> SyntaxShape {
-    let result = match bytes {
+    match bytes {
         b"any" => SyntaxShape::Any,
         b"binary" => SyntaxShape::Binary,
         b"block" => {
@@ -106,20 +106,18 @@ pub fn parse_shape_name(
                 }
 
                 if let Some(decl_id) = working_set.find_decl(cmd_name) {
-                    return SyntaxShape::CompleterWrapper(Box::new(shape), decl_id);
+                    SyntaxShape::CompleterWrapper(Box::new(shape), decl_id)
                 } else {
                     working_set.error(ParseError::UnknownCommand(cmd_span));
-                    return shape;
+                    shape
                 }
             } else {
                 //TODO: Handle error case for unknown shapes
                 working_set.error(ParseError::UnknownType(span));
-                return SyntaxShape::Any;
+                SyntaxShape::Any
             }
         }
-    };
-
-    result
+    }
 }
 
 fn parse_generic_shape(

crates/nu-parser/src/parser.rs

@@ -1688,7 +1688,7 @@ pub fn parse_int(working_set: &mut StateWorkingSet, span: Span) -> Expression {
             Expression::new(working_set, Expr::Int(num), span, Type::Int)
         } else {
             working_set.error(ParseError::InvalidLiteral(
-                format!("invalid digits for radix {}", radix),
+                format!("invalid digits for radix {radix}"),
                 "int".into(),
                 span,
             ));
@@ -3387,10 +3387,7 @@ pub fn parse_import_pattern(working_set: &mut StateWorkingSet, spans: &[Span]) -
                     "list"
                 };
                 working_set.error(ParseError::WrongImportPattern(
-                    format!(
-                        "{} member can be only at the end of an import pattern",
-                        what
-                    ),
+                    format!("{what} member can be only at the end of an import pattern"),
                     prev_span,
                 ));
                 return Expression::new(
@@ -6116,7 +6113,7 @@ fn check_record_key_or_value(
                 let colon_position = i + string_value.span.start;
                 ParseError::InvalidLiteral(
                     "colon".to_string(),
-                    format!("bare word specifying record {}", position),
+                    format!("bare word specifying record {position}"),
                     Span::new(colon_position, colon_position + 1),
                 )
             })