fix a bunch of the other clippy warnings that look interesting

src/comment.rs

@@ -405,7 +405,7 @@ impl CodeBlockAttribute {
     /// attributes are valid rust attributes
     /// See <https://doc.rust-lang.org/rustdoc/print.html#attributes>
     fn new(attributes: &str) -> CodeBlockAttribute {
-        for attribute in attributes.split(",") {
+        for attribute in attributes.split(',') {
             match attribute.trim() {
                 "" | "rust" | "should_panic" | "no_run" | "edition2015" | "edition2018"
                 | "edition2021" => (),
@@ -1384,7 +1384,7 @@ impl<'a> Iterator for LineClasses<'a> {
             None => unreachable!(),
         };
 
-        while let Some((kind, c)) = self.base.next() {
+        for (kind, c) in self.base.by_ref() {
             // needed to set the kind of the ending character on the last line
             self.kind = kind;
             if c == '\n' {

src/expr.rs

@@ -1207,11 +1207,11 @@ fn rewrite_int_lit(context: &RewriteContext<'_>, lit: &ast::Lit, shape: Shape) -
     let span = lit.span;
     let symbol = lit.token.symbol.as_str();
 
-    if symbol.starts_with("0x") {
+    if let Some(symbol_stripped) = symbol.strip_prefix("0x") {
         let hex_lit = match context.config.hex_literal_case() {
             HexLiteralCase::Preserve => None,
-            HexLiteralCase::Upper => Some(symbol[2..].to_ascii_uppercase()),
-            HexLiteralCase::Lower => Some(symbol[2..].to_ascii_lowercase()),
+            HexLiteralCase::Upper => Some(symbol_stripped.to_ascii_uppercase()),
+            HexLiteralCase::Lower => Some(symbol_stripped.to_ascii_lowercase()),
         };
         if let Some(hex_lit) = hex_lit {
             return wrap_str(

src/matches.rs

@@ -168,7 +168,7 @@ fn collect_beginning_verts(
         .map(|a| {
             context
                 .snippet(a.pat.span)
-                .starts_with("|")
+                .starts_with('|')
                 .then(|| a.pat.span().lo())
         })
         .collect()

src/modules.rs

@@ -197,7 +197,7 @@ impl<'ast, 'sess, 'c> ModResolver<'ast, 'sess> {
     /// Visit modules from AST.
     fn visit_mod_from_ast(
         &mut self,
-        items: &'ast Vec<rustc_ast::ptr::P<ast::Item>>,
+        items: &'ast [rustc_ast::ptr::P<ast::Item>],
     ) -> Result<(), ModuleResolutionError> {
         for item in items {
             if is_cfg_if(item) {

src/patterns.rs

@@ -456,11 +456,11 @@ fn rewrite_tuple_pat(
     context: &RewriteContext<'_>,
     shape: Shape,
 ) -> Option<String> {
-    let mut pat_vec: Vec<_> = pats.iter().map(|x| TuplePatField::Pat(x)).collect();
-
-    if pat_vec.is_empty() {
+    if pats.is_empty() {
         return Some(format!("{}()", path_str.unwrap_or_default()));
     }
+    let mut pat_vec: Vec<_> = pats.iter().map(TuplePatField::Pat).collect();
+
     let wildcard_suffix_len = count_wildcard_suffix_len(context, &pat_vec, span, shape);
     let (pat_vec, span) = if context.config.condense_wildcard_suffixes() && wildcard_suffix_len >= 2
     {