Rollup merge of rust-lang#98043 - TaKO8Ki:remove-unnecessary-to-strin…

…g, r=davidtwco

Remove unnecessary `to_string` and `String::new`

rust-lang@73fa217 changed the type of the `suggestion` argument to `impl ToString`. This patch removes unnecessary `to_string` and `String::new`.

cc: ```@davidtwco```

compiler/rustc_ast_lowering/src/expr.rs

@@ -1168,7 +1168,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                             .span_suggestion(
                                 e.span,
                                 "consider removing the trailing pattern",
-                                String::new(),
+                                "",
                                 rustc_errors::Applicability::MachineApplicable,
                             )
                             .emit();

compiler/rustc_ast_lowering/src/pat.rs

@@ -139,7 +139,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                         .span_suggestion_verbose(
                             sp,
                             &format!("if you don't need to use the contents of {}, discard the tuple's remaining fields", ident),
-                            "..".to_string(),
+                            "..",
                             Applicability::MaybeIncorrect,
                         )
                         .emit();

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -488,7 +488,7 @@ impl<'a> AstValidator<'a> {
             .span_suggestion(
                 replace_span,
                 &format!("provide a definition for the {}", ctx),
-                sugg.to_string(),
+                sugg,
                 Applicability::HasPlaceholders,
             )
             .emit();
@@ -522,7 +522,7 @@ impl<'a> AstValidator<'a> {
                 .span_suggestion(
                     span,
                     &format!("remove the {}", remove_descr),
-                    String::new(),
+                    "",
                     Applicability::MaybeIncorrect,
                 )
                 .span_label(self.current_extern_span(), "`extern` block begins here")
@@ -570,7 +570,7 @@ impl<'a> AstValidator<'a> {
             .span_suggestion(
                 body.span,
                 "remove the invalid body",
-                ";".to_string(),
+                ";",
                 Applicability::MaybeIncorrect,
             )
             .help(
@@ -599,7 +599,7 @@ impl<'a> AstValidator<'a> {
                 .span_suggestion_verbose(
                     span.until(ident.span.shrink_to_lo()),
                     "remove the qualifiers",
-                    "fn ".to_string(),
+                    "fn ",
                     Applicability::MaybeIncorrect,
                 )
                 .emit();
@@ -703,7 +703,7 @@ impl<'a> AstValidator<'a> {
             .span_suggestion(
                 generics.span,
                 "remove the parameters",
-                String::new(),
+                "",
                 Applicability::MachineApplicable,
             )
             .emit();
@@ -721,7 +721,7 @@ impl<'a> AstValidator<'a> {
         .span_suggestion(
             span,
             "remove the super traits or lifetime bounds",
-            String::new(),
+            "",
             Applicability::MachineApplicable,
         )
         .emit();
@@ -753,7 +753,7 @@ impl<'a> AstValidator<'a> {
             .span_suggestion(
                 total_span,
                 "remove these associated items",
-                String::new(),
+                "",
                 Applicability::MachineApplicable,
             )
             .span_label(ident_span, "auto trait cannot have associated items")
@@ -993,7 +993,7 @@ fn validate_generic_param_order(
             err.span_suggestion(
                 span,
                 "reorder the parameters: lifetimes, then consts and types",
-                ordered_params.clone(),
+                &ordered_params,
                 Applicability::MachineApplicable,
             );
             err.emit();

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -823,7 +823,7 @@ fn maybe_stage_features(sess: &Session, krate: &ast::Crate) {
                 err.span_suggestion(
                     attr.span,
                     "remove the attribute",
-                    String::new(),
+                    "",
                     Applicability::MachineApplicable,
                 );
             }

compiler/rustc_attr/src/builtin.rs

@@ -59,7 +59,7 @@ fn handle_errors(sess: &ParseSess, span: Span, error: AttrError) {
                     err.span_suggestion(
                         span,
                         "consider removing the prefix",
-                        lint_str[1..].to_string(),
+                        &lint_str[1..],
                         Applicability::MaybeIncorrect,
                     );
                 }
@@ -942,7 +942,7 @@ pub fn parse_repr_attr(sess: &Session, attr: &Attribute) -> Vec<ReprAttr> {
                         err.span_suggestion(
                             item.span(),
                             "supply an argument here",
-                            "align(...)".to_string(),
+                            "align(...)",
                             Applicability::HasPlaceholders,
                         );
                         err.emit();

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -225,7 +225,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                                     .map(|n| format!("`{}`", n))
                                     .unwrap_or_else(|| "the value".to_string())
                             ),
-                            "ref ".to_string(),
+                            "ref ",
                             Applicability::MachineApplicable,
                         );
                         in_pattern = true;
@@ -276,7 +276,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                                 .map(|n| format!("`{}`", n))
                                 .unwrap_or_else(|| "the mutable reference".to_string()),
                         ),
-                        "&mut *".to_string(),
+                        "&mut *",
                         Applicability::MachineApplicable,
                     );
                 }
@@ -1519,15 +1519,15 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             Ok(string) => {
                 if string.starts_with("async ") {
                     let pos = args_span.lo() + BytePos(6);
-                    (args_span.with_lo(pos).with_hi(pos), "move ".to_string())
+                    (args_span.with_lo(pos).with_hi(pos), "move ")
                 } else if string.starts_with("async|") {
                     let pos = args_span.lo() + BytePos(5);
-                    (args_span.with_lo(pos).with_hi(pos), " move".to_string())
+                    (args_span.with_lo(pos).with_hi(pos), " move")
                 } else {
-                    (args_span.shrink_to_lo(), "move ".to_string())
+                    (args_span.shrink_to_lo(), "move ")
                 }
             }
-            Err(_) => (args_span, "move |<args>| <body>".to_string()),
+            Err(_) => (args_span, "move |<args>| <body>"),
         };
         let kind = match use_span.generator_kind() {
             Some(generator_kind) => match generator_kind {

compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs

@@ -212,7 +212,7 @@ impl<'tcx> BorrowExplanation<'tcx> {
                                         "consider adding semicolon after the expression so its \
                                         temporaries are dropped sooner, before the local variables \
                                         declared by the block are dropped",
-                                        ";".to_string(),
+                                        ";",
                                         Applicability::MaybeIncorrect,
                                     );
                                 }

compiler/rustc_borrowck/src/diagnostics/mod.rs

@@ -1023,7 +1023,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                                      avoid moving into the `for` loop",
                                     ty,
                                 ),
-                                "&".to_string(),
+                                "&",
                                 Applicability::MaybeIncorrect,
                             );
                         }
@@ -1049,7 +1049,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                                             .map(|n| format!("`{}`", n))
                                             .unwrap_or_else(|| "the mutable reference".to_string()),
                                     ),
-                                    "&mut *".to_string(),
+                                    "&mut *",
                                     Applicability::MachineApplicable,
                                 );
                             }
@@ -1067,7 +1067,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                         err.span_suggestion_verbose(
                             fn_call_span.shrink_to_lo(),
                             "consider calling `.as_ref()` to borrow the type's contents",
-                            "as_ref().".to_string(),
+                            "as_ref().",
                             Applicability::MachineApplicable,
                         );
                     }

compiler/rustc_borrowck/src/diagnostics/move_errors.rs

@@ -417,7 +417,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
             err.span_suggestion_verbose(
                 span.shrink_to_hi(),
                 &format!("consider borrowing the `{}`'s content", diag_name.unwrap()),
-                ".as_ref()".to_string(),
+                ".as_ref()",
                 Applicability::MaybeIncorrect,
             );
         } else if let Some(use_spans) = use_spans {

compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs

@@ -295,7 +295,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                             err.span_suggestion_verbose(
                                 source_info.span.with_hi(source_info.span.lo() + BytePos(5)),
                                 "try removing `&mut` here",
-                                String::new(),
+                                "",
                                 Applicability::MachineApplicable,
                             );
                         } else {
@@ -316,7 +316,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                     err.span_suggestion_verbose(
                         decl.source_info.span.shrink_to_lo(),
                         "consider making the binding mutable",
-                        "mut ".to_string(),
+                        "mut ",
                         Applicability::MachineApplicable,
                     );
                 }
@@ -402,7 +402,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                 err.span_suggestion(
                     span,
                     "try removing `&mut` here",
-                    String::new(),
+                    "",
                     Applicability::MaybeIncorrect,
                 );
             }

compiler/rustc_borrowck/src/diagnostics/region_errors.rs

@@ -860,7 +860,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                 err.span_suggestion_verbose(
                     span.shrink_to_hi(),
                     "consider relaxing the implicit `'static` requirement",
-                    " + '_".to_string(),
+                    " + '_",
                     Applicability::MaybeIncorrect,
                 );
                 suggested = true;

compiler/rustc_borrowck/src/lib.rs

@@ -426,7 +426,7 @@ fn do_mir_borrowck<'a, 'tcx>(
                 .span_suggestion_short(
                     mut_span,
                     "remove this `mut`",
-                    String::new(),
+                    "",
                     Applicability::MachineApplicable,
                 )
                 .emit();

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/assert.rs

@@ -132,7 +132,7 @@ fn parse_assert<'a>(cx: &mut ExtCtxt<'a>, sp: Span, stream: TokenStream) -> PRes
         err.span_suggestion(
             parser.token.span,
             "try removing semicolon",
-            String::new(),
+            "",
             Applicability::MaybeIncorrect,
         );
         err.emit();
@@ -153,7 +153,7 @@ fn parse_assert<'a>(cx: &mut ExtCtxt<'a>, sp: Span, stream: TokenStream) -> PRes
             err.span_suggestion_short(
                 comma_span,
                 "try adding a comma",
-                ", ".to_string(),
+                ", ",
                 Applicability::MaybeIncorrect,
             );
             err.emit();

compiler/rustc_builtin_macros/src/derive.rs

@@ -142,7 +142,7 @@ fn report_path_args(sess: &Session, meta: &ast::MetaItem) {
     let report_error = |title, action| {
         let span = meta.span.with_lo(meta.path.span.hi());
         sess.struct_span_err(span, title)
-            .span_suggestion(span, action, String::new(), Applicability::MachineApplicable)
+            .span_suggestion(span, action, "", Applicability::MachineApplicable)
             .emit();
     };
     match meta.kind {

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_builtin_macros/src/test.rs

@@ -118,7 +118,7 @@ pub fn expand_test_or_bench(
         };
         err.span_label(attr_sp, "the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions")
             .span_label(item.span, format!("expected a non-associated function, found {} {}", item.kind.article(), item.kind.descr()))
-            .span_suggestion(attr_sp, "replace with conditional compilation to make the item only exist when tests are being run", String::from("#[cfg(test)]"), Applicability::MaybeIncorrect)
+            .span_suggestion(attr_sp, "replace with conditional compilation to make the item only exist when tests are being run", "#[cfg(test)]", Applicability::MaybeIncorrect)
             .emit();
 
         return vec![Annotatable::Item(item)];

compiler/rustc_const_eval/src/transform/check_consts/check.rs

@@ -1035,7 +1035,7 @@ fn emit_unstable_in_stable_error(ccx: &ConstCx<'_, '_>, span: Span, gate: Symbol
         .span_suggestion(
             attr_span,
             "if it is not part of the public API, make this function unstably const",
-            concat!(r#"#[rustc_const_unstable(feature = "...", issue = "...")]"#, '\n').to_owned(),
+            concat!(r#"#[rustc_const_unstable(feature = "...", issue = "...")]"#, '\n'),
             Applicability::HasPlaceholders,
         )
         .span_suggestion(

compiler/rustc_expand/src/base.rs

@@ -1194,7 +1194,7 @@ pub fn expr_to_spanned_string<'a>(
                 err.span_suggestion(
                     expr.span.shrink_to_lo(),
                     "consider removing the leading `b`",
-                    String::new(),
+                    "",
                     Applicability::MaybeIncorrect,
                 );
                 Some((err, true))

compiler/rustc_expand/src/expand.rs

@@ -945,7 +945,7 @@ pub fn ensure_complete_parse<'a>(
                 err.span_suggestion(
                     semi_span,
                     "you might be missing a semicolon here",
-                    ";".to_owned(),
+                    ";",
                     Applicability::MaybeIncorrect,
                 );
             }

compiler/rustc_expand/src/mbe/macro_rules.rs

@@ -102,7 +102,7 @@ fn emit_frag_parse_err(
                 e.span_suggestion_verbose(
                     site_span.shrink_to_hi(),
                     "add `;` to interpret the expansion as a statement",
-                    ";".to_string(),
+                    ";",
                     Applicability::MaybeIncorrect,
                 );
             }
@@ -357,7 +357,7 @@ fn expand_macro<'cx>(
                     err.span_suggestion_short(
                         comma_span,
                         "missing comma here",
-                        ", ".to_string(),
+                        ", ",
                         Applicability::MachineApplicable,
                     );
                 }

compiler/rustc_expand/src/mbe/metavar_expr.rs

@@ -52,7 +52,7 @@ impl MetaVarExpr {
                 err.span_suggestion(
                     ident.span,
                     "supported expressions are count, ignore, index and length",
-                    String::new(),
+                    "",
                     Applicability::MachineApplicable,
                 );
                 return Err(err);
@@ -142,7 +142,7 @@ fn parse_ident<'sess>(
         err.span_suggestion(
             token.span,
             &format!("try removing `{}`", &token_str),
-            String::new(),
+            "",
             Applicability::MaybeIncorrect,
         );
         return Err(err);