Do not enforce ~const constness effects in typeck if rustc_do_mot_const_check

Author: compiler-errors

Diff for: compiler/rustc_hir_typeck/src/callee.rs

@@ -851,6 +851,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             return;
         }
 
+        // If we have `rustc_do_not_const_check`, do not check `~const` bounds.
+        if self.tcx.has_attr(self.body_id, sym::rustc_do_not_const_check) {
+            return;
+        }
+
         let host = match self.tcx.hir().body_const_context(self.body_id) {
             Some(hir::ConstContext::Const { .. } | hir::ConstContext::Static(_)) => {
                 ty::HostPolarity::Const

Diff for: tests/ui/traits/const-traits/do-not-const-check.rs

@@ -1,5 +1,6 @@
 //@ check-pass
-#![feature(const_trait_impl, rustc_attrs)]
+#![feature(const_trait_impl, rustc_attrs, effects)]
+//~^ WARN the feature `effects` is incomplete
 
 #[const_trait]
 trait IntoIter {