From 031243898eaa138056ea7248fb37324ffaa561e1 Mon Sep 17 00:00:00 2001
From: lcnr <rust@lcnr.de>
Date: Mon, 19 Jul 2021 13:03:29 +0200
Subject: [PATCH] check for cycles in `default_anon_const_substs`

---
 compiler/rustc_typeck/src/collect/type_of.rs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/compiler/rustc_typeck/src/collect/type_of.rs b/compiler/rustc_typeck/src/collect/type_of.rs
index 9b10874b8bcf..2f0a5eb79bc1 100644
--- a/compiler/rustc_typeck/src/collect/type_of.rs
+++ b/compiler/rustc_typeck/src/collect/type_of.rs
@@ -275,6 +275,11 @@ fn get_path_containing_arg_in_pat<'hir>(
 }
 
 pub(super) fn default_anon_const_substs(tcx: TyCtxt<'_>, def_id: DefId) -> SubstsRef<'_> {
+    let generics = tcx.generics_of(def_id);
+    if let Some(parent) = generics.parent {
+        let _cycle_check = tcx.predicates_of(parent);
+    }
+
     let substs = InternalSubsts::identity_for_item(tcx, def_id);
     // We only expect substs with the following type flags as default substs.
     //