Add a data race test

Author: HKalbasi

tests/fail/both_borrows/spurious_write_may_be_added_data_race.rs

@@ -0,0 +1,49 @@
+//@revisions: stack tree
+//@[tree]compile-flags: -Zmiri-tree-borrows-strong
+use std::sync::{Arc, Barrier};
+
+#[derive(Copy, Clone)]
+struct SendPtr(*const u32);
+
+unsafe impl Send for SendPtr {}
+
+type IdxBarrier = (usize, Arc<Barrier>);
+
+// Barriers to enforce the interleaving.
+// This macro expects `synchronized!(thread, msg)` where `thread` is a `IdxBarrier`,
+// and `msg` is the message to be displayed when the thread reaches this point in the execution.
+macro_rules! synchronized {
+    ($thread:expr, $msg:expr) => {{
+        let (thread_id, barrier) = &$thread;
+        eprintln!("Thread {} executing: {}", thread_id, $msg);
+        barrier.wait();
+    }};
+}
+
+fn may_insert_spurious_write(_x: &mut u32, b: IdxBarrier) {
+    synchronized!(b, "after enter");
+    synchronized!(b, "before exit");
+}
+
+fn main() {
+    let target = &mut 42;
+    let target_alias = &*target;
+    let target_alias_ptr = SendPtr(target_alias as *const _);
+
+    let barrier = Arc::new(Barrier::new(2));
+    let bx = (1, Arc::clone(&barrier));
+    let by = (2, Arc::clone(&barrier));
+
+    let join_handle = std::thread::spawn(move || {
+        synchronized!(bx, "before read");
+        let ptr = target_alias_ptr;
+        // now `target_alias` is invalid
+        let _val = unsafe { *ptr.0 };
+        //~[stack]^ ERROR: /read access .* tag does not exist in the borrow stack/
+        //~[tree]| ERROR: /read access through .* is forbidden/
+        synchronized!(bx, "after read");
+    });
+
+    may_insert_spurious_write(target, by);
+    let _ = join_handle.join();
+}

tests/fail/both_borrows/spurious_write_may_be_added_data_race.stack.stderr

@@ -0,0 +1,27 @@
+Thread 2 executing: after enter
+Thread 1 executing: before read
+error: Undefined Behavior: attempting a read access using <TAG> at ALLOC[0x0], but that tag does not exist in the borrow stack for this location
+  --> tests/fail/both_borrows/spurious_write_may_be_added_data_race.rs:LL:CC
+   |
+LL |         let _val = unsafe { *ptr.0 };
+   |                             ^^^^^^ this error occurs as part of an access at ALLOC[0x0..0x4]
+   |
+   = help: this indicates a potential bug in the program: it performed an invalid operation, but the Stacked Borrows rules it violated are still experimental
+   = help: see https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.md for further information
+help: <TAG> was created by a SharedReadOnly retag at offsets [0x0..0x4]
+  --> tests/fail/both_borrows/spurious_write_may_be_added_data_race.rs:LL:CC
+   |
+LL |     let target_alias_ptr = SendPtr(target_alias as *const _);
+   |                                    ^^^^^^^^^^^^
+help: <TAG> was later invalidated at offsets [0x0..0x4] by a Unique function-entry retag inside this call
+  --> tests/fail/both_borrows/spurious_write_may_be_added_data_race.rs:LL:CC
+   |
+LL |     may_insert_spurious_write(target, by);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = note: BACKTRACE (of the first span) on thread `unnamed-ID`:
+   = note: inside closure at tests/fail/both_borrows/spurious_write_may_be_added_data_race.rs:LL:CC
+
+note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
+
+error: aborting due to 1 previous error
+

tests/fail/both_borrows/spurious_write_may_be_added_data_race.tree.stderr

@@ -0,0 +1,30 @@
+Thread 2 executing: after enter
+Thread 1 executing: before read
+error: Undefined Behavior: read access through <TAG> at ALLOC[0x0] is forbidden
+  --> tests/fail/both_borrows/spurious_write_may_be_added_data_race.rs:LL:CC
+   |
+LL |         let _val = unsafe { *ptr.0 };
+   |                             ^^^^^^ Undefined Behavior occurred here
+   |
+   = help: this indicates a potential bug in the program: it performed an invalid operation, but the Tree Borrows rules it violated are still experimental
+   = help: see https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/tree-borrows.md for further information
+   = help: the accessed tag <TAG> is foreign to the protected tag <TAG> (i.e., it is not a child)
+   = help: this foreign read access would cause the protected tag <TAG> (currently Active) to become Disabled
+   = help: protected tags must never be Disabled
+help: the accessed tag <TAG> was created here
+  --> tests/fail/both_borrows/spurious_write_may_be_added_data_race.rs:LL:CC
+   |
+LL |     let target_alias = &*target;
+   |                        ^^^^^^^^
+help: the protected tag <TAG> was created here, in the initial state Active
+  --> tests/fail/both_borrows/spurious_write_may_be_added_data_race.rs:LL:CC
+   |
+LL | fn may_insert_spurious_write(_x: &mut u32, b: IdxBarrier) {
+   |                              ^^
+   = note: BACKTRACE (of the first span) on thread `unnamed-ID`:
+   = note: inside closure at tests/fail/both_borrows/spurious_write_may_be_added_data_race.rs:LL:CC
+
+note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
+
+error: aborting due to 1 previous error
+