From 72cec0562cf3ff5a50f4318e316e188325cda54c Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Wed, 17 Apr 2019 15:20:33 +0200
Subject: [PATCH] add tests for fixes: sharing no longer leaks, and we can
 handle entering interior mutability

---
 .../compile-fail/stacked_borrows/illegal_read6.rs |  8 ++++++++
 .../{refcell.rs => interior_mutability.rs}        | 15 +++++++++++++++
 2 files changed, 23 insertions(+)
 create mode 100644 tests/compile-fail/stacked_borrows/illegal_read6.rs
 rename tests/run-pass/stacked-borrows/{refcell.rs => interior_mutability.rs} (70%)

diff --git a/tests/compile-fail/stacked_borrows/illegal_read6.rs b/tests/compile-fail/stacked_borrows/illegal_read6.rs
new file mode 100644
index 00000000000..dc378147290
--- /dev/null
+++ b/tests/compile-fail/stacked_borrows/illegal_read6.rs
@@ -0,0 +1,8 @@
+// Creating a shared reference does not leak the data to raw pointers.
+fn main() { unsafe {
+    let x = &mut 0;
+    let raw = x as *mut _;
+    let x = &mut *x; // kill `raw`
+    let _y = &*x; // this should not activate `raw` again
+    let _val = *raw; //~ ERROR borrow stack
+} }
diff --git a/tests/run-pass/stacked-borrows/refcell.rs b/tests/run-pass/stacked-borrows/interior_mutability.rs
similarity index 70%
rename from tests/run-pass/stacked-borrows/refcell.rs
rename to tests/run-pass/stacked-borrows/interior_mutability.rs
index dddc7089d02..33f44d0093e 100644
--- a/tests/run-pass/stacked-borrows/refcell.rs
+++ b/tests/run-pass/stacked-borrows/interior_mutability.rs
@@ -1,8 +1,12 @@
+#![feature(maybe_uninit, maybe_uninit_ref)]
+use std::mem::MaybeUninit;
+use std::cell::Cell;
 use std::cell::RefCell;
 
 fn main() {
     aliasing_mut_and_shr();
     aliasing_frz_and_shr();
+    into_interior_mutability();
 }
 
 fn aliasing_mut_and_shr() {
@@ -42,3 +46,14 @@ fn inner(rc: &RefCell<i32>, aliasing: &i32) {
     inner(&rc, &*bshr);
     assert_eq!(*rc.borrow(), 23);
 }
+
+// Getting a pointer into a union with interior mutability used to be tricky
+// business (https://github.com/rust-lang/miri/issues/615), but it should work
+// now.
+fn into_interior_mutability() {
+    let mut x: MaybeUninit<(Cell<u32>, u32)> = MaybeUninit::uninit();
+    x.as_ptr();
+    x.write((Cell::new(0), 1));
+    let ptr = unsafe { x.get_ref() };
+    assert_eq!(ptr.1, 1);
+}
-- 
2.44.0