NFC don't convert types to identical types

compiler/rustc_ast_lowering/src/expr.rs

@@ -1260,9 +1260,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
  );
 
  // `a = lhs1; b = lhs2;`.
- let stmts = self
- .arena
- .alloc_from_iter(std::iter::once(destructure_let).chain(assignments.into_iter()));
+ let stmts = self.arena.alloc_from_iter(std::iter::once(destructure_let).chain(assignments));
 
  // Wrap everything in a block.
  hir::ExprKind::Block(self.block_all(whole_span, stmts, None), None)

compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs

@@ -607,7 +607,7 @@ pub fn file_metadata<'ll>(cx: &CodegenCx<'ll, '_>, source_file: &SourceFile) ->
 
  if let Ok(rel_path) = abs_path.strip_prefix(working_directory) {
  (
- working_directory.to_string_lossy().into(),
+ working_directory.to_string_lossy(),
  rel_path.to_string_lossy().into_owned(),
  )
  } else {

compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/mod.rs

@@ -396,7 +396,7 @@ pub fn build_coroutine_variant_struct_type_di_node<'ll, 'tcx>(
  })
  .collect();
 
- state_specific_fields.into_iter().chain(common_fields.into_iter()).collect()
+ state_specific_fields.into_iter().chain(common_fields).collect()
  },
  |cx| build_generic_type_param_di_nodes(cx, coroutine_type_and_layout.ty),
  )

compiler/rustc_data_structures/src/sorted_map.rs

@@ -198,7 +198,7 @@ impl<K: Ord, V> SortedMap<K, V> {
  if index == self.data.len() || elements.last().unwrap().0 < self.data[index].0 {
  // We can copy the whole range without having to mix with
  // existing elements.
- self.data.splice(index..index, elements.into_iter());
+ self.data.splice(index..index, elements);
  return;
  }
 

compiler/rustc_hir/src/hir.rs

@@ -1560,7 +1560,7 @@ impl Expr<'_> {
  ExprKind::Call(..) => ExprPrecedence::Call,
  ExprKind::MethodCall(..) => ExprPrecedence::MethodCall,
  ExprKind::Tup(_) => ExprPrecedence::Tup,
- ExprKind::Binary(op, ..) => ExprPrecedence::Binary(op.node.into()),
+ ExprKind::Binary(op, ..) => ExprPrecedence::Binary(op.node),
  ExprKind::Unary(..) => ExprPrecedence::Unary,
  ExprKind::Lit(_) => ExprPrecedence::Lit,
  ExprKind::Type(..) | ExprKind::Cast(..) => ExprPrecedence::Cast,
@@ -1700,11 +1700,9 @@ impl Expr<'_> {
  // them being used only for its side-effects.
  base.can_have_side_effects()
  }
- ExprKind::Struct(_, fields, init) => fields
- .iter()
- .map(|field| field.expr)
- .chain(init.into_iter())
- .any(|e| e.can_have_side_effects()),
+ ExprKind::Struct(_, fields, init) => {
+ fields.iter().map(|field| field.expr).chain(init).any(|e| e.can_have_side_effects())
+ }
 
  ExprKind::Array(args)
  | ExprKind::Tup(args)

compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs

@@ -350,7 +350,7 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
  // Nested poly trait refs have the binders concatenated
  let mut full_binders =
  self.map.late_bound_vars.entry(*hir_id).or_default().clone();
- full_binders.extend(supertrait_bound_vars.into_iter());
+ full_binders.extend(supertrait_bound_vars);
  break (full_binders, BinderScopeType::Concatenating);
  }
  }

compiler/rustc_hir_typeck/src/errors.rs

@@ -573,13 +573,13 @@ impl rustc_errors::AddToDiagnostic for CastUnknownPointerSub {
  {
  match self {
  CastUnknownPointerSub::To(span) => {
- let msg = f(diag, crate::fluent_generated::hir_typeck_label_to.into());
+ let msg = f(diag, crate::fluent_generated::hir_typeck_label_to);
  diag.span_label(span, msg);
- let msg = f(diag, crate::fluent_generated::hir_typeck_note.into());
+ let msg = f(diag, crate::fluent_generated::hir_typeck_note);
  diag.note(msg);
  }
  CastUnknownPointerSub::From(span) => {
- let msg = f(diag, crate::fluent_generated::hir_typeck_label_from.into());
+ let msg = f(diag, crate::fluent_generated::hir_typeck_label_from);
  diag.span_label(span, msg);
  }
  }

compiler/rustc_hir_typeck/src/method/probe.rs

@@ -1548,9 +1548,9 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
  );
 
  let candidate_obligations = impl_obligations
- .chain(norm_obligations.into_iter())
+ .chain(norm_obligations)
  .chain(ref_obligations.iter().cloned())
- .chain(normalization_obligations.into_iter());
+ .chain(normalization_obligations);
 
  // Evaluate those obligations to see if they might possibly hold.
  for o in candidate_obligations {

compiler/rustc_infer/src/infer/outlives/verify.rs

@@ -130,12 +130,7 @@ impl<'cx, 'tcx> VerifyBoundCx<'cx, 'tcx> {
  // see the extensive comment in projection_must_outlive
  let recursive_bound = {
  let mut components = smallvec![];
- compute_alias_components_recursive(
- self.tcx,
- alias_ty_as_ty.into(),
- &mut components,
- visited,
- );
+ compute_alias_components_recursive(self.tcx, alias_ty_as_ty, &mut components, visited);
  self.bound_from_components(&components, visited)
  };
 

compiler/rustc_infer/src/infer/relate/combine.rs

@@ -552,7 +552,7 @@ impl<'infcx, 'tcx> CombineFields<'infcx, 'tcx> {
  }
 
  pub fn register_obligations(&mut self, obligations: PredicateObligations<'tcx>) {
- self.obligations.extend(obligations.into_iter());
+ self.obligations.extend(obligations);
  }
 
  pub fn register_predicates(&mut self, obligations: impl IntoIterator<Item: ToPredicate<'tcx>>) {

compiler/rustc_mir_dataflow/src/value_analysis.rs

@@ -956,11 +956,7 @@ impl Map {
  // The local is not tracked at all, so it does not alias anything.
  return;
  };
- let elems = place
- .projection
- .iter()
- .map(|&elem| elem.try_into())
- .chain(tail_elem.map(Ok).into_iter());
+ let elems = place.projection.iter().map(|&elem| elem.try_into()).chain(tail_elem.map(Ok));
  for elem in elems {
  // A field aliases the parent place.
  if let Some(vi) = self.places[index].value_index {

compiler/rustc_mir_transform/src/dataflow_const_prop.rs

@@ -496,7 +496,7 @@ impl<'a, 'tcx> ConstAnalysis<'a, 'tcx> {
  FlatSet::Elem(scalar) => {
  let ty = op.ty(self.local_decls, self.tcx);
  self.tcx.layout_of(self.param_env.and(ty)).map_or(FlatSet::Top, |layout| {
- FlatSet::Elem(ImmTy::from_scalar(scalar.into(), layout))
+ FlatSet::Elem(ImmTy::from_scalar(scalar, layout))
  })
  }
  FlatSet::Bottom => FlatSet::Bottom,

compiler/rustc_parse/src/parser/item.rs

@@ -923,7 +923,7 @@ impl<'a> Parser<'a> {
  );
  let where_predicates_split = before_where_clause.predicates.len();
  let mut predicates = before_where_clause.predicates;
- predicates.extend(after_where_clause.predicates.into_iter());
+ predicates.extend(after_where_clause.predicates);
  let where_clause = WhereClause {
  has_where_token: before_where_clause.has_where_token
  || after_where_clause.has_where_token,

compiler/rustc_parse/src/validate_attr.rs

@@ -215,7 +215,7 @@ fn emit_malformed_attribute(
  } else {
  "the following are the possible correct uses"
  },
- suggestions.into_iter(),
+ suggestions,
  Applicability::HasPlaceholders,
  )
  .emit();

compiler/rustc_resolve/src/rustdoc.rs

@@ -407,8 +407,7 @@ fn parse_links<'md>(doc: &'md str) -> Vec<Box<str>> {
  doc,
  main_body_opts(),
  Some(&mut broken_link_callback),
- )
- .into_iter();
+ );
  let mut links = Vec::new();
 
  while let Some(event) = event_iter.next() {

compiler/rustc_session/src/config.rs

@@ -1579,7 +1579,7 @@ impl CheckCfg {
 pub fn build_configuration(sess: &Session, mut user_cfg: Cfg) -> Cfg {
  // Combine the configuration requested by the session (command line) with
  // some default and generated configuration items.
- user_cfg.extend(default_configuration(sess).into_iter());
+ user_cfg.extend(default_configuration(sess));
  user_cfg
 }
 

compiler/rustc_smir/src/rustc_smir/context.rs

@@ -158,7 +158,6 @@ impl<'tcx> Context for TablesWrapper<'tcx> {
  let crate_name = tables.tcx.crate_name(*crate_num).to_string();
  (name == crate_name).then(|| smir_crate(tables.tcx, *crate_num))
  })
- .into_iter()
  .flatten()
  .collect();
  crates

compiler/rustc_trait_selection/src/traits/object_safety.rs

@@ -345,7 +345,7 @@ fn generics_require_sized_self(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
  // Search for a predicate like `Self : Sized` amongst the trait bounds.
  let predicates = tcx.predicates_of(def_id);
  let predicates = predicates.instantiate_identity(tcx).predicates;
- elaborate(tcx, predicates.into_iter()).any(|pred| match pred.kind().skip_binder() {
+ elaborate(tcx, predicates).any(|pred| match pred.kind().skip_binder() {
  ty::ClauseKind::Trait(ref trait_pred) => {
  trait_pred.def_id() == sized_def_id && trait_pred.self_ty().is_param(0)
  }

compiler/rustc_trait_selection/src/traits/util.rs

@@ -220,9 +220,8 @@ pub fn impl_subject_and_oblig<'a, 'tcx>(
  selcx.infcx.at(&ObligationCause::dummy(), param_env).normalize(predicates);
  let impl_obligations = super::predicates_for_generics(cause, param_env, predicates);
 
- let impl_obligations = impl_obligations
- .chain(normalization_obligations1.into_iter())
- .chain(normalization_obligations2.into_iter());
+ let impl_obligations =
+ impl_obligations.chain(normalization_obligations1).chain(normalization_obligations2);
 
  (subject, impl_obligations)
 }

src/librustdoc/clean/mod.rs

@@ -743,7 +743,7 @@ pub(crate) fn clean_generics<'tcx>(
  .into_iter()
  .map(|(lifetime, bounds)| WherePredicate::RegionPredicate { lifetime, bounds }),
  )
- .chain(eq_predicates.into_iter())
+ .chain(eq_predicates)
  .collect(),
  }
 }

src/librustdoc/html/markdown.rs

@@ -1383,7 +1383,7 @@ impl LangString {
  };
 
  if custom_code_classes_in_docs {
- call(&mut TagIterator::new(string, extra).into_iter())
+ call(&mut TagIterator::new(string, extra))
  } else {
  call(&mut tokens(string))
  }

src/librustdoc/lint.rs

@@ -33,7 +33,7 @@ where
  let lints = || {
  lint::builtin::HardwiredLints::get_lints()
  .into_iter()
- .chain(rustc_lint::SoftLints::get_lints().into_iter())
+ .chain(rustc_lint::SoftLints::get_lints())
  };
 
  let lint_opts = lints()
@@ -46,7 +46,7 @@ where
  filter_call(lint)
  }
  })
- .chain(lint_opts.into_iter())
+ .chain(lint_opts)
  .collect::<Vec<_>>();
 
  let lint_caps = lints()

src/librustdoc/passes/check_custom_code_classes.rs

@@ -48,7 +48,7 @@ struct TestsWithCustomClasses {
 
 impl crate::doctest::Tester for TestsWithCustomClasses {
  fn add_test(&mut self, _: String, config: LangString, _: usize) {
- self.custom_classes_found.extend(config.added_classes.into_iter());
+ self.custom_classes_found.extend(config.added_classes);
  }
 }
 

src/librustdoc/visit_ast.rs

@@ -168,10 +168,11 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
  })
  .collect::<Vec<_>>()
  })
- .chain(
- [Cfg::Cfg(sym::test, None), Cfg::Cfg(sym::doc, None), Cfg::Cfg(sym::doctest, None)]
- .into_iter(),
- )
+ .chain([
+ Cfg::Cfg(sym::test, None),
+ Cfg::Cfg(sym::doc, None),
+ Cfg::Cfg(sym::doctest, None),
+ ])
  .collect();
 
  self.cx.cache.exact_paths = self.exact_paths;