more clippy::complexity fixes

 redundant_guards
redundant_slicing
filter_next
needless_borrowed_reference
useless_format

Author: matthiaskrgr

compiler/rustc_hir_typeck/src/coercion.rs

@@ -1701,7 +1701,7 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> {
  && !ty.is_never()
 {
 let indentation = ifletNone = block.expr
- && let[.., last] = &block.stmts[..]
+ && let[.., last] = &block.stmts
 {
  tcx.sess.source_map().indentation_before(last.span).unwrap_or_else(String::new)
 }elseifletSome(expr) = block.expr{
@@ -1710,7 +1710,7 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> {
 String::new()
 };
 ifletNone = block.expr
- && let[.., last] = &block.stmts[..]
+ && let[.., last] = &block.stmts
 {
  err.span_suggestion_verbose(
  last.span.shrink_to_hi(),
@@ -1750,7 +1750,7 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> {
 }
 }
 ifletNone = block.expr
- && let[.., last] = &block.stmts[..]
+ && let[.., last] = &block.stmts
 {
  sugg.push((last.span.shrink_to_hi(),format!("\n{indentation}None")));
 }elseifletSome(expr) = block.expr{

compiler/rustc_hir_typeck/src/demand.rs

@@ -862,7 +862,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
  mutability,
 ),
 ),
-match&args[..]{
+match&args {
 [] => (base.span.shrink_to_hi().with_hi(deref.span.hi()),")".to_string()),
 [first, ..] => (base.span.between(first.span),", ".to_string()),
 },

compiler/rustc_infer/src/infer/error_reporting/mod.rs

@@ -2452,7 +2452,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
 
 if !suggs.is_empty(){
  err.multipart_suggestion_verbose(
-format!("{msg}"),
+ msg,
  suggs,
 Applicability::MaybeIncorrect,// Issue #41966
 );

compiler/rustc_mir_build/src/thir/pattern/mod.rs

@@ -174,7 +174,7 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
 span:Span,
 ) -> Result<PatKind<'tcx>,ErrorGuaranteed>{
 if lo_expr.is_none() && hi_expr.is_none(){
-let msg = format!("found twice-open range pattern (`..`) outside of error recovery");
+let msg = "found twice-open range pattern (`..`) outside of error recovery";
 returnErr(self.tcx.sess.span_delayed_bug(span, msg));
 }
 

compiler/rustc_resolve/src/imports.rs

@@ -1063,12 +1063,8 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
  initial_binding.res()
 });
 let res = binding.res();
-let has_ambiguity_error = this
-.ambiguity_errors
-.iter()
-.filter(|error| !error.warning)
-.next()
-.is_some();
+let has_ambiguity_error =
+ this.ambiguity_errors.iter().any(|error| !error.warning);
 if res == Res::Err || has_ambiguity_error {
  this.tcx
 .sess

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -1829,13 +1829,12 @@ impl<'a: 'ast, 'ast, 'tcx> LateResolutionVisitor<'a, '_, 'ast, 'tcx> {
 )
 .iter()
 .filter_map(|candidate| candidate.did)
-.filter(|did| {
+.find(|did| {
 self.r
 .tcx
 .get_attrs(*did, sym::rustc_diagnostic_item)
 .any(|attr| attr.value_str() == Some(sym::Default))
-})
-.next();
+});
 letSome(default_trait) = default_trait else{
 return;
 };
@@ -1880,11 +1879,7 @@ impl<'a: 'ast, 'ast, 'tcx> LateResolutionVisitor<'a, '_, 'ast, 'tcx> {
 };
 
  fields.is_some_and(|fields| {
- fields
-.iter()
-.filter(|vis| !self.r.is_accessible_from(**vis,self.parent_scope.module))
-.next()
-.is_some()
+ fields.iter().any(|vis| !self.r.is_accessible_from(*vis,self.parent_scope.module))
 })
 }
 

compiler/rustc_smir/src/rustc_smir/convert/mir.rs

@@ -707,7 +707,7 @@ impl<'tcx> Stable<'tcx> for rustc_middle::mir::Const<'tcx> {
 let id = tables.intern_const(*self);
 Const::new(kind, ty, id)
 }
- mir::Const::Val(val, ty)ifmatches!(val,mir::ConstValue::ZeroSized) => {
+ mir::Const::Val(mir::ConstValue::ZeroSized, ty) => {
 let ty = ty.stable(tables);
 let id = tables.intern_const(*self);
 Const::new(ConstantKind::ZeroSized, ty, id)

compiler/rustc_trait_selection/src/infer.rs

@@ -101,11 +101,10 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
 self.tcx.impl_trait_ref(impl_def_id).map(|r| (impl_def_id, r))
 })
 .map(|(impl_def_id, imp)| (impl_def_id, imp.skip_binder()))
-.filter(|(_, imp)| match imp.self_ty().peel_refs().kind(){
+.find(|(_, imp)| match imp.self_ty().peel_refs().kind(){
  ty::Adt(i_def, _)if i_def.did() == def.did() => true,
  _ => false,
 })
-.next()
 {
 letmut fulfill_cx = FulfillmentCtxt::new(self);
 // We get all obligations from the impl to talk about specific

compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs

@@ -2167,7 +2167,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
 })
 .collect();
  err.multipart_suggestion(
-format!("consider wrapping the function in a closure"),
+"consider wrapping the function in a closure",
 vec![
 (arg.span.shrink_to_lo(), format!("|{}| ", closure_names.join(", "))),
 (arg.span.shrink_to_hi(), format!("({})", call_names.join(", "))),

src/librustdoc/clean/types.rs

@@ -2245,8 +2245,8 @@ impl GenericArgs {
 }
 pub(crate)fnbindings<'a>(&'aself) -> Box<dynIterator<Item = TypeBinding> + 'a>{
 matchself{
-&GenericArgs::AngleBracketed{ref bindings, .. } => Box::new(bindings.iter().cloned()),
-&GenericArgs::Parenthesized{ref output, .. } => Box::new(
+GenericArgs::AngleBracketed{ bindings, .. } => Box::new(bindings.iter().cloned()),
+GenericArgs::Parenthesized{ output, .. } => Box::new(
  output
 .as_ref()
 .map(|ty| TypeBinding{
@@ -2270,8 +2270,8 @@ impl<'a> IntoIterator for &'a GenericArgs {
 typeItem = GenericArg;
 fninto_iter(self) -> Self::IntoIter{
 matchself{
-&GenericArgs::AngleBracketed{ref args, .. } => Box::new(args.iter().cloned()),
-&GenericArgs::Parenthesized{ref inputs, .. } => {
+GenericArgs::AngleBracketed{ args, .. } => Box::new(args.iter().cloned()),
+GenericArgs::Parenthesized{ inputs, .. } => {
 Box::new(inputs.iter().cloned().map(GenericArg::Type))
 }
 }