remove unnecessary to_string and String::new for tool_only_span_suggestion

compiler/rustc_builtin_macros/src/asm.rs

@@ -363,7 +363,7 @@ fn err_duplicate_option<'a>(p: &mut Parser<'a>, symbol: Symbol, span: Span) {
     err.tool_only_span_suggestion(
         full_span,
         "remove this option",
-        String::new(),
+        "",
         Applicability::MachineApplicable,
     );
 

compiler/rustc_builtin_macros/src/format.rs

@@ -330,7 +330,7 @@ impl<'a, 'b> Context<'a, 'b> {
                                 err.tool_only_span_suggestion(
                                     sp,
                                     &format!("use the `{}` trait", name),
-                                    (*fmt).to_string(),
+                                    *fmt,
                                     Applicability::MaybeIncorrect,
                                 );
                             }

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -2596,7 +2596,7 @@ impl<'a> Parser<'a> {
         err.tool_only_span_suggestion(
             label.ident.span.until(self.token.span),
             "remove this block label",
-            String::new(),
+            "",
             Applicability::MachineApplicable,
         );
         err.emit();

compiler/rustc_resolve/src/diagnostics.rs

@@ -271,7 +271,7 @@ impl<'a> Resolver<'a> {
                 err.tool_only_span_suggestion(
                     import.use_span_with_attributes,
                     "remove unnecessary import",
-                    String::new(),
+                    "",
                     Applicability::MaybeIncorrect,
                 );
             }
@@ -396,12 +396,7 @@ impl<'a> Resolver<'a> {
         // previous imports.
         if found_closing_brace {
             if let Some(span) = extend_span_to_previous_binding(self.session, span) {
-                err.tool_only_span_suggestion(
-                    span,
-                    message,
-                    String::new(),
-                    Applicability::MaybeIncorrect,
-                );
+                err.tool_only_span_suggestion(span, message, "", Applicability::MaybeIncorrect);
             } else {
                 // Remove the entire line if we cannot extend the span back, this indicates an
                 // `issue_52891::{self}` case.

compiler/rustc_typeck/src/check/_match.rs

@@ -174,7 +174,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     err.tool_only_span_suggestion(
                         semi_span,
                         "remove this semicolon",
-                        String::new(),
+                        "",
                         Applicability::MaybeIncorrect,
                     );
                 }),

src/tools/clippy/clippy_lints/src/needless_late_init.rs

@@ -281,7 +281,7 @@ fn check<'tcx>(
                     diag.tool_only_span_suggestion(
                         local_stmt.span,
                         "remove the local",
-                        String::new(),
+                        "",
                         Applicability::MachineApplicable,
                     );