Fix rust-lang#8748

clippy_lints/src/shadow.rs

@@ -158,11 +158,26 @@ impl<'tcx> LateLintPass<'tcx> for Shadow {
     }
 }
 
+type Result<T> = std::result::Result<T, LifetimeError>;
+
+#[derive(Debug, Clone)]
+struct LifetimeError;
+
+impl std::fmt::Display for LifetimeError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "Invalid lifetime")
+    }
+}
+
 fn is_shadow(cx: &LateContext<'_>, owner: LocalDefId, first: ItemLocalId, second: ItemLocalId) -> bool {
     let scope_tree = cx.tcx.region_scope_tree(owner.to_def_id());
-    let first_scope = scope_tree.var_scope(first).unwrap();
-    let second_scope = scope_tree.var_scope(second).unwrap();
-    scope_tree.is_subscope_of(second_scope, first_scope)
+    if let Some(first_scope) = scope_tree.var_scope(first) {
+        if let Some(second_scope) = scope_tree.var_scope(second) {
+            return scope_tree.is_subscope_of(second_scope, first_scope);
+        }
+    }
+
+    false
 }
 
 fn lint_shadow(cx: &LateContext<'_>, pat: &Pat<'_>, shadowed: HirId, span: Span) {

tests/ui/shadow.rs

@@ -88,4 +88,11 @@ pub async fn foo2(_a: i32, _b: i64) {
     let _b = _a;
 }
 
+fn ice_8748() {
+    let _ = [0; {
+        let x = 1;
+        if let Some(x) = Some(1) { x } else { 1 }
+    }];
+}
+
 fn main() {}