From 6f543d5cebe220595174a135eca92765df8c97e3 Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Fri, 24 Jan 2025 16:19:25 +0000
Subject: [PATCH] Add regression test

---
 tests/ui/parallel-rustc/cycle_crash.rs     |  5 +++++
 tests/ui/parallel-rustc/cycle_crash.stderr | 18 ++++++++++++++++++
 2 files changed, 23 insertions(+)
 create mode 100644 tests/ui/parallel-rustc/cycle_crash.rs
 create mode 100644 tests/ui/parallel-rustc/cycle_crash.stderr

diff --git a/tests/ui/parallel-rustc/cycle_crash.rs b/tests/ui/parallel-rustc/cycle_crash.rs
new file mode 100644
index 000000000000..94ae11aef39d
--- /dev/null
+++ b/tests/ui/parallel-rustc/cycle_crash.rs
@@ -0,0 +1,5 @@
+//@ compile-flags: -Z threads=2
+
+const FOO: usize = FOO; //~ERROR cycle detected when simplifying constant for the type system `FOO`
+
+fn main() {}
diff --git a/tests/ui/parallel-rustc/cycle_crash.stderr b/tests/ui/parallel-rustc/cycle_crash.stderr
new file mode 100644
index 000000000000..7af3b8ee532c
--- /dev/null
+++ b/tests/ui/parallel-rustc/cycle_crash.stderr
@@ -0,0 +1,18 @@
+error[E0391]: cycle detected when simplifying constant for the type system `FOO`
+  --> $DIR/cycle_crash.rs:3:1
+   |
+LL | const FOO: usize = FOO;
+   | ^^^^^^^^^^^^^^^^
+   |
+note: ...which requires const-evaluating + checking `FOO`...
+  --> $DIR/cycle_crash.rs:3:20
+   |
+LL | const FOO: usize = FOO;
+   |                    ^^^
+   = note: ...which again requires simplifying constant for the type system `FOO`, completing the cycle
+   = note: cycle used when running analysis passes on this crate
+   = 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`.