From 3f9015b22d774dd2af0c3c95dbfb0270d5e0bf7e Mon Sep 17 00:00:00 2001
From: Bastian Kauschke <bastian_kauschke@hotmail.de>
Date: Tue, 22 Sep 2020 11:55:03 +0200
Subject: [PATCH] visit impl self ty + trait

---
 compiler/rustc_typeck/src/collect.rs          | 12 +++++++++
 .../const_evaluatable_checked/impl-bounds.rs  | 25 +++++++++++++++++++
 2 files changed, 37 insertions(+)
 create mode 100644 src/test/ui/const-generics/const_evaluatable_checked/impl-bounds.rs

diff --git a/compiler/rustc_typeck/src/collect.rs b/compiler/rustc_typeck/src/collect.rs
index d341e7eec41a3..a571bd58abc34 100644
--- a/compiler/rustc_typeck/src/collect.rs
+++ b/compiler/rustc_typeck/src/collect.rs
@@ -2098,6 +2098,18 @@ fn const_evaluatable_predicates_of<'tcx>(
     let node = tcx.hir().get(hir_id);
 
     let mut collector = ConstCollector { tcx, preds: FxIndexSet::default() };
+    if let hir::Node::Item(item) = node {
+        if let hir::ItemKind::Impl { ref of_trait, ref self_ty, .. } = item.kind {
+            if let Some(of_trait) = of_trait {
+                warn!("const_evaluatable_predicates_of({:?}): visit impl trait_ref", def_id);
+                collector.visit_trait_ref(of_trait);
+            }
+
+            warn!("const_evaluatable_predicates_of({:?}): visit_self_ty", def_id);
+            collector.visit_ty(self_ty);
+        }
+    }
+
     if let Some(generics) = node.generics() {
         warn!("const_evaluatable_predicates_of({:?}): visit_generics", def_id);
         collector.visit_generics(generics);
diff --git a/src/test/ui/const-generics/const_evaluatable_checked/impl-bounds.rs b/src/test/ui/const-generics/const_evaluatable_checked/impl-bounds.rs
new file mode 100644
index 0000000000000..193a365f9b65b
--- /dev/null
+++ b/src/test/ui/const-generics/const_evaluatable_checked/impl-bounds.rs
@@ -0,0 +1,25 @@
+// check-pass
+#![feature(const_generics, const_evaluatable_checked)]
+#![allow(incomplete_features)]
+
+use std::mem::size_of;
+
+struct Foo<T, const N: usize>(T);
+
+impl<T> Foo<T, { size_of::<T>() }> {
+    fn test() {
+        let _: [u8; std::mem::size_of::<T>()];
+    }
+}
+
+trait Bar<const N: usize> {
+    fn test_me();
+}
+
+impl<T> Bar<{ size_of::<T>() }> for Foo<T, 3> {
+    fn test_me() {
+        let _: [u8; std::mem::size_of::<T>()];
+    }
+}
+
+fn main() {}