Auto merge of rust-lang#89644 - matthiaskrgr:clippy_perf_okt, r=jyn514

some clippy::perf fixes

Author: bors

compiler/rustc_parse/src/parser/expr.rs

@@ -1096,7 +1096,7 @@ impl<'a> Parser<'a> {
             (Err(ref mut err), Some((mut snapshot, ExprKind::Path(None, path)))) => {
                 let name = pprust::path_to_string(&path);
                 snapshot.bump(); // `(`
-                match snapshot.parse_struct_fields(path.clone(), false, token::Paren) {
+                match snapshot.parse_struct_fields(path, false, token::Paren) {
                     Ok((fields, ..)) if snapshot.eat(&token::CloseDelim(token::Paren)) => {
                         // We have are certain we have `Enum::Foo(a: 3, b: 4)`, suggest
                         // `Enum::Foo { a: 3, b: 4 }` or `Enum::Foo(3, 4)`.

compiler/rustc_typeck/src/check/cast.rs

@@ -431,7 +431,7 @@ impl<'a, 'tcx> CastCheck<'tcx> {
                         .sess
                         .source_map()
                         .span_to_snippet(self.expr.span)
-                        .map_or(false, |snip| snip.starts_with("("));
+                        .map_or(false, |snip| snip.starts_with('('));
 
                     // Very crude check to see whether the expression must be wrapped
                     // in parentheses for the suggestion to work (issue #89497).

compiler/rustc_typeck/src/check/expr.rs

@@ -1887,7 +1887,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             };
         let expr_snippet =
             self.tcx.sess.source_map().span_to_snippet(expr.span).unwrap_or(String::new());
-        let is_wrapped = expr_snippet.starts_with("(") && expr_snippet.ends_with(")");
+        let is_wrapped = expr_snippet.starts_with('(') && expr_snippet.ends_with(')');
         let after_open = expr.span.lo() + rustc_span::BytePos(1);
         let before_close = expr.span.hi() - rustc_span::BytePos(1);