diff --git a/src/test/ui/consts/issue-51559.rs b/src/test/ui/consts/issue-51559.rs
new file mode 100644
index 0000000000000..429947269385b
--- /dev/null
+++ b/src/test/ui/consts/issue-51559.rs
@@ -0,0 +1,7 @@
+#![feature(const_raw_ptr_to_usize_cast)]
+
+const BAR: *mut () = ((|| 3) as fn() -> i32) as *mut ();
+pub const FOO: usize = unsafe { BAR as usize };
+//~^ ERROR it is undefined behavior to use this value
+
+fn main() {}
diff --git a/src/test/ui/consts/issue-51559.stderr b/src/test/ui/consts/issue-51559.stderr
new file mode 100644
index 0000000000000..917c54ddaef1e
--- /dev/null
+++ b/src/test/ui/consts/issue-51559.stderr
@@ -0,0 +1,11 @@
+error[E0080]: it is undefined behavior to use this value
+  --> $DIR/issue-51559.rs:4:1
+   |
+LL | pub const FOO: usize = unsafe { BAR as usize };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered a pointer, but expected initialized plain (non-pointer) bytes
+   |
+   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0080`.