Prefer if chain to let-else

Author: qsantos

clippy_lints/src/methods/double_ended_iterator_last.rs

@@ -9,34 +9,18 @@ use rustc_span::{Span, sym};
 usesuper::DOUBLE_ENDED_ITERATOR_LAST;
 
 pub(super)fncheck(cx:&LateContext<'_>,expr:&'_Expr<'_>,self_expr:&'_Expr<'_>,call_span:Span){
-let typeck = cx.typeck_results();
-
-// Check if the current "last" method is that of the Iterator trait
-if !is_trait_method(cx, expr, sym::Iterator){
-return;
-}
-
-// Find id for DoubleEndedIterator trait
-letSome(deiter_id) = cx.tcx.get_diagnostic_item(sym::DoubleEndedIterator)else{
-return;
-};
-
-// Find the type of self
-let self_type = typeck.expr_ty(self_expr).peel_refs();
-
-// Check that the object implements the DoubleEndedIterator trait
-if !implements_trait(cx, self_type, deiter_id,&[]){
-return;
+ifis_trait_method(cx, expr, sym::Iterator)
+ && letSome(deiter_id) = cx.tcx.get_diagnostic_item(sym::DoubleEndedIterator)
+ && implements_trait(cx, cx.typeck_results().expr_ty(self_expr).peel_refs(), deiter_id,&[])
+{
+span_lint_and_sugg(
+ cx,
+DOUBLE_ENDED_ITERATOR_LAST,
+ call_span,
+"called `Iterator::last` on a `DoubleEndedIterator`; this will needlessly iterate the entire iterator",
+"try",
+"next_back()".to_string(),
+Applicability::MachineApplicable,
+);
 }
-
-// Emit lint
-span_lint_and_sugg(
- cx,
-DOUBLE_ENDED_ITERATOR_LAST,
- call_span,
-"called `Iterator::last` on a `DoubleEndedIterator`; this will needlessly iterate the entire iterator",
-"try",
-"next_back()".to_string(),
-Applicability::MachineApplicable,
-);
 }