Mark some once-again-unreachable paths as unreachable.

This undoes the changes from #121482 and #121586, now that stashed errors
will trigger more early aborts.

Author: nnethercote

compiler/rustc_lint/src/array_into_iter.rs

@@ -70,15 +70,11 @@ impl<'tcx> LateLintPass<'tcx> for ArrayIntoIter {
 
             // Check if the method call actually calls the libcore
             // `IntoIterator::into_iter`.
-            let trait_id = cx
-                .typeck_results()
-                .type_dependent_def_id(expr.hir_id)
-                .and_then(|did| cx.tcx.trait_of_item(did));
-            if trait_id.is_none()
-                || !cx.tcx.is_diagnostic_item(sym::IntoIterator, trait_id.unwrap())
-            {
-                return;
-            }
+            let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap();
+            match cx.tcx.trait_of_item(def_id) {
+                Some(trait_id) if cx.tcx.is_diagnostic_item(sym::IntoIterator, trait_id) => {}
+                _ => return,
+            };
 
             // As this is a method call expression, we have at least one argument.
             let receiver_ty = cx.typeck_results().expr_ty(receiver_arg);

compiler/rustc_privacy/src/lib.rs

@@ -988,10 +988,7 @@ impl<'tcx> Visitor<'tcx> for NamePrivacyVisitor<'tcx> {
     fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
         if let hir::ExprKind::Struct(qpath, fields, ref base) = expr.kind {
             let res = self.typeck_results().qpath_res(qpath, expr.hir_id);
-            let Some(adt) = self.typeck_results().expr_ty(expr).ty_adt_def() else {
-                self.tcx.dcx().span_delayed_bug(expr.span, "no adt_def for expression");
-                return;
-            };
+            let adt = self.typeck_results().expr_ty(expr).ty_adt_def().unwrap();
             let variant = adt.variant_of_res(res);
             if let Some(base) = *base {
                 // If the expression uses FRU we need to make sure all the unmentioned fields