From fdff100545850376e0f48d382ca3f92c959ff1cc Mon Sep 17 00:00:00 2001
From: Oli Scherer <git-spam-no-reply9815368754983@oli-obk.de>
Date: Fri, 8 Mar 2024 06:36:37 +0000
Subject: [PATCH] Add regression test

---
 .../const_check_false_cycle.current.stderr    | 34 +++++++++++++++++++
 .../rpit/const_check_false_cycle.rs           | 15 ++++++++
 2 files changed, 49 insertions(+)
 create mode 100644 tests/ui/impl-trait/rpit/const_check_false_cycle.current.stderr
 create mode 100644 tests/ui/impl-trait/rpit/const_check_false_cycle.rs

diff --git a/tests/ui/impl-trait/rpit/const_check_false_cycle.current.stderr b/tests/ui/impl-trait/rpit/const_check_false_cycle.current.stderr
new file mode 100644
index 00000000000..78c7c164f59
--- /dev/null
+++ b/tests/ui/impl-trait/rpit/const_check_false_cycle.current.stderr
@@ -0,0 +1,34 @@
+error[E0391]: cycle detected when computing type of opaque `f::{opaque#0}`
+  --> $DIR/const_check_false_cycle.rs:9:17
+   |
+LL | const fn f() -> impl Eq {
+   |                 ^^^^^^^
+   |
+note: ...which requires borrow-checking `f`...
+  --> $DIR/const_check_false_cycle.rs:9:1
+   |
+LL | const fn f() -> impl Eq {
+   | ^^^^^^^^^^^^^^^^^^^^^^^
+note: ...which requires promoting constants in MIR for `f`...
+  --> $DIR/const_check_false_cycle.rs:9:1
+   |
+LL | const fn f() -> impl Eq {
+   | ^^^^^^^^^^^^^^^^^^^^^^^
+note: ...which requires const checking `f`...
+  --> $DIR/const_check_false_cycle.rs:9:1
+   |
+LL | const fn f() -> impl Eq {
+   | ^^^^^^^^^^^^^^^^^^^^^^^
+   = note: ...which requires computing whether `f::{opaque#0}` is freeze...
+   = note: ...which requires evaluating trait selection obligation `f::{opaque#0}: core::marker::Freeze`...
+   = note: ...which again requires computing type of opaque `f::{opaque#0}`, completing the cycle
+note: cycle used when computing type of `f::{opaque#0}`
+  --> $DIR/const_check_false_cycle.rs:9:17
+   |
+LL | const fn f() -> impl Eq {
+   |                 ^^^^^^^
+   = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0391`.
diff --git a/tests/ui/impl-trait/rpit/const_check_false_cycle.rs b/tests/ui/impl-trait/rpit/const_check_false_cycle.rs
new file mode 100644
index 00000000000..5b6b667e1fa
--- /dev/null
+++ b/tests/ui/impl-trait/rpit/const_check_false_cycle.rs
@@ -0,0 +1,15 @@
+//! This test causes a cycle error when checking whether the
+//! return type is `Freeze` during const checking, even though
+//! the information is readily available.
+
+//@ revisions: current next
+//@[next] compile-flags: -Znext-solver
+//@[next] check-pass
+
+const fn f() -> impl Eq {
+    //[current]~^ ERROR cycle detected
+    g()
+}
+const fn g() {}
+
+fn main() {}