From 343a359109a48f4ece657831bf0331e22d108800 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Mon, 30 Jan 2023 19:04:55 +0000
Subject: [PATCH] Use ObligationCtxt::new_in_snapshot in
 satisfied_from_param_env

---
 .../src/traits/const_evaluatable.rs           |  2 +-
 ...m-with-associated-const-in-where-clause.rs | 17 ++++++++
 ...gle-satisfied-ConstEvaluatable-in-probe.rs | 39 +++++++++++++++++++
 3 files changed, 57 insertions(+), 1 deletion(-)
 create mode 100644 tests/rustdoc/document-item-with-associated-const-in-where-clause.rs
 create mode 100644 tests/ui/const-generics/generic_const_exprs/single-satisfied-ConstEvaluatable-in-probe.rs

diff --git a/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs b/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs
index f779d9dd8d9..786473457ae 100644
--- a/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs
+++ b/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs
@@ -219,7 +219,7 @@ fn satisfied_from_param_env<'tcx>(
     }
 
     if let Some(Ok(c)) = single_match {
-        let ocx = ObligationCtxt::new(infcx);
+        let ocx = ObligationCtxt::new_in_snapshot(infcx);
         assert!(ocx.eq(&ObligationCause::dummy(), param_env, c.ty(), ct.ty()).is_ok());
         assert!(ocx.eq(&ObligationCause::dummy(), param_env, c, ct).is_ok());
         assert!(ocx.select_all_or_error().is_empty());
diff --git a/tests/rustdoc/document-item-with-associated-const-in-where-clause.rs b/tests/rustdoc/document-item-with-associated-const-in-where-clause.rs
new file mode 100644
index 00000000000..c9408ef3360
--- /dev/null
+++ b/tests/rustdoc/document-item-with-associated-const-in-where-clause.rs
@@ -0,0 +1,17 @@
+#![feature(generic_const_exprs)]
+#![allow(incomplete_features)]
+
+pub trait Enumerable {
+    const N: usize;
+}
+
+#[derive(Clone)]
+pub struct SymmetricGroup<S>
+where
+    S: Enumerable,
+    [(); S::N]: Sized,
+{
+    _phantom: std::marker::PhantomData<S>,
+}
+
+fn main() {}
diff --git a/tests/ui/const-generics/generic_const_exprs/single-satisfied-ConstEvaluatable-in-probe.rs b/tests/ui/const-generics/generic_const_exprs/single-satisfied-ConstEvaluatable-in-probe.rs
new file mode 100644
index 00000000000..0ba0c5a72ef
--- /dev/null
+++ b/tests/ui/const-generics/generic_const_exprs/single-satisfied-ConstEvaluatable-in-probe.rs
@@ -0,0 +1,39 @@
+// check-pass
+
+#![allow(incomplete_features)]
+#![feature(generic_const_exprs)]
+
+use std::marker::PhantomData;
+
+pub trait Bytes {
+    const BYTES: usize;
+}
+
+#[derive(Clone, Debug)]
+pub struct Conster<OT>
+where
+    OT: Bytes,
+    [(); OT::BYTES]: Sized,
+{
+    _offset_type: PhantomData<fn(OT) -> OT>,
+}
+
+impl<OT> Conster<OT>
+where
+    OT: Bytes,
+    [(); OT::BYTES]: Sized,
+{
+    pub fn new() -> Self {
+        Conster { _offset_type: PhantomData }
+    }
+}
+
+pub fn make_conster<COT>() -> Conster<COT>
+where
+    COT: Bytes,
+    [(); COT::BYTES]: Sized,
+{
+    Conster::new()
+}
+
+fn main() {}