remove unnecessary to_string and String::new

Author: TaKO8Ki

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,
  );
  }