chore: Clippy and dead code elimination pass (#16469)

- **Fix `clippy::non_canonical_partial_ord_impl`**
- **Clippy from stable `needless_return`**
- **Dead code found by `cargo +stable clippy`**
- **Remove dead function used by pre-uu `mv --update`**
- **clippy::manual_is_multiple_of**

## Release notes summary - What our users need to know
N/A

crates/nu-command/src/database/values/definitions/db_schema.rs

@@ -1,7 +0,0 @@
-use super::db_table::DbTable;
-
-#[derive(Clone, PartialEq, Eq, Debug)]
-pub struct DbSchema {
-    pub name: String,
-    pub tables: Vec<DbTable>,
-}

crates/nu-command/src/database/values/definitions/mod.rs

@@ -3,5 +3,4 @@ pub mod db_constraint;
 pub mod db_foreignkey;
 pub mod db_index;
 pub mod db_row;
-pub mod db_schema;
 pub mod db_table;

crates/nu-command/src/database/values/sqlite.rs

@@ -619,7 +619,7 @@ fn prepared_statement_to_nu_list(
     // got heavily in the way
     let row_values = match params {
         NuSqlParams::List(params) => {
-            let refs: Vec<&dyn ToSql> = params.iter().map(|value| (&**value)).collect();
+            let refs: Vec<&dyn ToSql> = params.iter().map(|value| &**value).collect();
 
             let row_results = stmt.query_map(refs.as_slice(), |row| {
                 Ok(convert_sqlite_row_to_nu_value(row, call_span, &columns))

crates/nu-command/src/filesystem/util.rs

@@ -1,16 +1,5 @@
 use dialoguer::Input;
-use std::{
-    error::Error,
-    path::{Path, PathBuf},
-};
-
-#[derive(Debug, Eq, Ord, PartialEq, PartialOrd)]
-pub struct Resource {
-    pub at: usize,
-    pub location: PathBuf,
-}
-
-impl Resource {}
+use std::error::Error;
 
 pub fn try_interaction(
     interactive: bool,
@@ -56,34 +45,3 @@ fn get_interactive_confirmation(prompt: String) -> Result<bool, Box<dyn Error>>
         Ok(false)
     }
 }
-
-/// Return `Some(true)` if the last change time of the `src` old than the `dst`,
-/// otherwisie return `Some(false)`. Return `None` if the `src` or `dst` doesn't exist.
-#[allow(dead_code)]
-pub fn is_older(src: &Path, dst: &Path) -> Option<bool> {
-    if !dst.exists() || !src.exists() {
-        return None;
-    }
-    #[cfg(unix)]
-    {
-        use std::os::unix::fs::MetadataExt;
-        let src_ctime = std::fs::metadata(src)
-            .map(|m| m.ctime())
-            .unwrap_or(i64::MIN);
-        let dst_ctime = std::fs::metadata(dst)
-            .map(|m| m.ctime())
-            .unwrap_or(i64::MAX);
-        Some(src_ctime <= dst_ctime)
-    }
-    #[cfg(windows)]
-    {
-        use std::os::windows::fs::MetadataExt;
-        let src_ctime = std::fs::metadata(src)
-            .map(|m| m.last_write_time())
-            .unwrap_or(u64::MIN);
-        let dst_ctime = std::fs::metadata(dst)
-            .map(|m| m.last_write_time())
-            .unwrap_or(u64::MAX);
-        Some(src_ctime <= dst_ctime)
-    }
-}

crates/nu-command/src/math/median.rs

@@ -85,7 +85,7 @@ enum Pick {
 }
 
 pub fn median(values: &[Value], span: Span, head: Span) -> Result<Value, ShellError> {
-    let take = if values.len() % 2 == 0 {
+    let take = if values.len().is_multiple_of(2) {
         Pick::MedianAverage
     } else {
         Pick::Median

crates/nu-command/src/platform/ulimit.rs

@@ -474,11 +474,11 @@ fn parse_limit(
             } else if val == "hard" {
                 Ok(hard_limit)
             } else {
-                return Err(ShellError::IncorrectValue {
+                Err(ShellError::IncorrectValue {
                     msg: "Only unlimited, soft and hard are supported for strings".into(),
                     val_span,
                     call_span,
-                });
+                })
             }
         }
         _ => Err(ShellError::TypeMismatch {

crates/nu-parser/src/parser.rs

@@ -2197,7 +2197,8 @@ pub fn parse_string_interpolation(working_set: &mut StateWorkingSet, span: Span)
                 0
             };
 
-            if current_byte == b'(' && (!double_quote || preceding_consecutive_backslashes % 2 == 0)
+            if current_byte == b'('
+                && (!double_quote || preceding_consecutive_backslashes.is_multiple_of(2))
             {
                 mode = InterpolationMode::Expression;
                 if token_start < b {

crates/nu-path/src/path.rs

@@ -2861,7 +2861,7 @@ impl<Form: PathForm> Eq for Path<Form> {}
 
 impl<Form: PathForm> PartialOrd for Path<Form> {
     fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
-        Some(self.inner.cmp(&other.inner))
+        Some(self.cmp(other))
     }
 }
 
@@ -2887,7 +2887,7 @@ impl<Form: PathForm> Eq for PathBuf<Form> {}
 
 impl<Form: PathForm> PartialOrd for PathBuf<Form> {
     fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
-        Some(self.inner.cmp(&other.inner))
+        Some(self.cmp(other))
     }
 }
 

crates/nu-pretty-hex/src/pretty_hex.rs

@@ -88,8 +88,8 @@ impl HexConfig {
     }
 
     fn delimiter(&self, i: usize) -> &'static str {
-        if i > 0 && self.chunk > 0 && i % self.chunk == 0 {
-            if self.group > 0 && i % (self.group * self.chunk) == 0 {
+        if i > 0 && self.chunk > 0 && i.is_multiple_of(self.chunk) {
+            if self.group > 0 && i.is_multiple_of(self.group * self.chunk) {
                 "  "
             } else {
                 " "

crates/nu-term-grid/src/grid.rs

@@ -282,7 +282,7 @@ impl Grid {
 
     fn columns_dimensions(&self, num_columns: usize) -> Dimensions {
         let mut num_lines = self.cells.len() / num_columns;
-        if self.cells.len() % num_columns != 0 {
+        if !self.cells.len().is_multiple_of(num_columns) {
             num_lines += 1;
         }
 
@@ -315,7 +315,7 @@ impl Grid {
                 col_total_width_so_far += cell.width;
             } else {
                 let mut theoretical_max_num_lines = self.cell_count / theoretical_min_num_cols;
-                if self.cell_count % theoretical_min_num_cols != 0 {
+                if !self.cell_count.is_multiple_of(theoretical_min_num_cols) {
                     theoretical_max_num_lines += 1;
                 }
                 return theoretical_max_num_lines;
@@ -374,7 +374,7 @@ impl Grid {
             // The number of columns is the number of cells divided by the number
             // of lines, *rounded up*.
             let mut num_columns = self.cell_count / num_lines;
-            if self.cell_count % num_lines != 0 {
+            if !self.cell_count.is_multiple_of(num_lines) {
                 num_columns += 1;
             }
             // Early abort: if there are so many columns that the width of the