fix the check for which expressions read never type

...wrt `type_ascribe`/unsafe binders -- the check was infinitely
recursive before.

Author: WaffleLapkin

compiler/rustc_middle/src/hir/mod.rs

@@ -251,7 +251,7 @@ impl<'tcx> TyCtxt<'tcx> {
                     // Place-preserving expressions only constitute reads if their
                     // parent expression constitutes a read.
                     ExprKind::Type(..) | ExprKind::UnsafeBinderCast(..) => {
-                        self.expr_guaranteed_to_constitute_read_for_never(expr)
+                        self.expr_guaranteed_to_constitute_read_for_never(parent_expr)
                     }
 
                     ExprKind::Assign(lhs, _, _) => {

tests/crashes/nested_type_ascription.rs …reachable-code/nested_type_ascription.rstests/crashes/nested_type_ascription.rs renamed to tests/ui/unreachable-code/nested_type_ascription.rs tests/crashes/nested_type_ascription.rs renamed to tests/ui/unreachable-code/nested_type_ascription.rs

@@ -3,7 +3,7 @@
 // This checks that a nested type ascription doesn't cause a crash when the
 // compiler checks if it constitutes a read of the never type.
 //
-//@ known-bug: #149542
+//@ check-pass
 
 #![feature(never_type)]
 #![feature(type_ascription)]