[unused_enumerate_index]: Use if-let chain

Author: Ethiraric

clippy_lints/src/loops/unused_enumerate_index.rs

@@ -8,55 +8,34 @@ use rustc_lint::LateContext;
 use rustc_middle::ty;
 
 /// Checks for the `UNUSED_ENUMERATE_INDEX` lint.
-pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, pat: &'tcx Pat<'_>, arg: &'tcx Expr<'_>, body: &'tcx Expr<'_>) {
-    let PatKind::Tuple([index, elem], _) = pat.kind else {
-        return;
-    };
-
-    let ExprKind::MethodCall(_method, self_arg, [], _) = arg.kind else {
-        return;
-    };
-
-    let ty = cx.typeck_results().expr_ty(arg);
-
-    if !pat_is_wild(cx, &index.kind, body) {
-        return;
-    }
-
-    let name = match *ty.kind() {
-        ty::Adt(base, _substs) => cx.tcx.def_path_str(base.did()),
-        _ => return,
-    };
-
-    if name != "std::iter::Enumerate" && name != "core::iter::Enumerate" {
-        return;
+pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, pat: &Pat<'tcx>, arg: &Expr<'_>, body: &'tcx Expr<'tcx>) {
+    if let PatKind::Tuple([index, elem], _) = pat.kind
+        && let ExprKind::MethodCall(_method, self_arg, [], _) = arg.kind
+        && let ty = cx.typeck_results().expr_ty(arg)
+        && pat_is_wild(cx, &index.kind, body)
+        && let ty::Adt(base, _) = *ty.kind()
+        && let name = cx.tcx.def_path_str(base.did())
+        && (name == "std::iter::Enumerate" || name == "core::iter::Enumerate")
+        && let Some((DefKind::AssocFn, call_id)) = cx.typeck_results().type_dependent_def(arg.hir_id)
+        && let call_name = cx.tcx.def_path_str(call_id)
+        && (call_name == "std::iter::Iterator::enumerate" || call_name == "core::iter::Iterator::enumerate")
+    {
+        span_lint_and_then(
+            cx,
+            UNUSED_ENUMERATE_INDEX,
+            arg.span,
+            "you seem to use `.enumerate()` and immediately discard the index",
+            |diag| {
+                let base_iter = sugg::Sugg::hir(cx, self_arg, "base iter");
+                multispan_sugg(
+                    diag,
+                    "remove the `.enumerate()` call",
+                    vec![
+                        (pat.span, snippet(cx, elem.span, "..").into_owned()),
+                        (arg.span, base_iter.to_string()),
+                    ],
+                );
+            },
+        );
     }
-
-    let Some((DefKind::AssocFn, call_id)) = cx.typeck_results().type_dependent_def(arg.hir_id) else {
-        return;
-    };
-
-    let call_name = cx.tcx.def_path_str(call_id);
-
-    if call_name != "std::iter::Iterator::enumerate" && call_name != "core::iter::Iterator::enumerate" {
-        return;
-    }
-
-    span_lint_and_then(
-        cx,
-        UNUSED_ENUMERATE_INDEX,
-        arg.span,
-        "you seem to use `.enumerate()` and immediately discard the index",
-        |diag| {
-            let base_iter = sugg::Sugg::hir(cx, self_arg, "base iter");
-            multispan_sugg(
-                diag,
-                "remove the `.enumerate()` call",
-                vec![
-                    (pat.span, snippet(cx, elem.span, "..").into_owned()),
-                    (arg.span, base_iter.to_string()),
-                ],
-            );
-        },
-    );
 }