Rollup merge of rust-lang#98191 - TaKO8Ki:remove-rest-of-unnecessary-to-string, r=Dylan-DPC

Remove the rest of unnecessary `to_string`

I removed most of unnecessary `to_string` in rust-lang#98043. This patch removes the rest of them I missed.

Author: Dylan-DPC

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -2042,9 +2042,9 @@ impl<'a> Parser<'a> {
                 match pat.kind {
                     PatKind::Ident(_, ident, _) => (
                         ident,
-                        "self: ".to_string(),
+                        "self: ",
                         ": TypeName".to_string(),
-                        "_: ".to_string(),
+                        "_: ",
                         pat.span.shrink_to_lo(),
                         pat.span.shrink_to_hi(),
                         pat.span.shrink_to_lo(),
@@ -2058,9 +2058,9 @@ impl<'a> Parser<'a> {
                                 let mutab = mutab.prefix_str();
                                 (
                                     ident,
-                                    "self: ".to_string(),
+                                    "self: ",
                                     format!("{ident}: &{mutab}TypeName"),
-                                    "_: ".to_string(),
+                                    "_: ",
                                     pat.span.shrink_to_lo(),
                                     pat.span,
                                     pat.span.shrink_to_lo(),

src/tools/clippy/clippy_utils/src/sugg.rs

@@ -771,7 +771,7 @@ impl<T: LintContext> DiagnosticExt<T> for rustc_errors::Diagnostic {
             }
         }
 
-        self.span_suggestion(remove_span, msg, String::new(), applicability);
+        self.span_suggestion(remove_span, msg, "", applicability);
     }
 }