Auto merge of #1614 - RalfJung:raw-retag, r=RalfJung

Stacked Borrows: test raw-ref-to-field with raw ptr tracking

Adds a test for rust-lang/rust#78597 (blocked on that landing first)

Author: bors

README.md

@@ -411,7 +411,7 @@ Violations of [Stacked Borrows] found that are likely bugs (but Stacked Borrows
 * [TiKV creating overlapping mutable reference and raw pointer](https://github.com/tikv/tikv/pull/7709)
 * [Windows `Env` iterator using a raw pointer outside its valid memory area](https://github.com/rust-lang/rust/pull/70479)
 * [`VecDeque::iter_mut` creating overlapping mutable references](https://github.com/rust-lang/rust/issues/74029)
-* [Standard library `SipHasher` using a raw pointer outside its valid memory area](https://github.com/rust-lang/rust/pull/78484)
+* [Various standard library aliasing issues involving raw pointers](https://github.com/rust-lang/rust/pull/78602)
 
 ## License
 

rust-version

@@ -1 +1 @@
-a53fb30e3bf2655b0563da6d561c23cda5f3ec11
+5cdf5b882da9e8b7c73b5cadeb7745cb68f6ff63

tests/run-pass/rc.rs

@@ -1,3 +1,5 @@
+// compile-flags: -Zmiri-track-raw-pointers
+// ignore-windows (FIXME: tracking raw pointers does not work on Windows)
 #![feature(new_uninit)]
 #![feature(get_mut_unchecked)]
 

tests/run-pass/stacked-borrows/int-to-ptr.rs

@@ -0,0 +1,13 @@
+fn main() {
+    ref_raw_int_raw();
+}
+
+// Just to make sure that casting a ref to raw, to int and back to raw
+// and only then using it works. This rules out ideas like "do escape-to-raw lazily";
+// after casting to int and back, we lost the tag that could have let us do that.
+fn ref_raw_int_raw() {
+    let mut x = 3;
+    let xref = &mut x;
+    let xraw = xref as *mut i32 as usize as *mut i32;
+    assert_eq!(unsafe { *xraw }, 3);
+}

tests/run-pass/stacked-borrows/stacked-borrows.rs

@@ -1,8 +1,12 @@
+// compile-flags: -Zmiri-track-raw-pointers
+// ignore-windows (FIXME: tracking raw pointers does not work on Windows)
+#![feature(raw_ref_macros)]
+use std::ptr;
+    
 // Test various stacked-borrows-related things.
 fn main() {
     read_does_not_invalidate1();
     read_does_not_invalidate2();
-    ref_raw_int_raw();
     mut_raw_then_mut_shr();
     mut_shr_then_mut_raw();
     mut_raw_mut();
@@ -12,6 +16,7 @@ fn main() {
     two_raw();
     shr_and_raw();
     disjoint_mutable_subborrows();
+    raw_ref_to_part();
 }
 
 // Make sure that reading from an `&mut` does, like reborrowing to `&`,
@@ -37,16 +42,6 @@ fn read_does_not_invalidate2() {
     assert_eq!(*foo(&mut (1, 2)), 2);
 }
 
-// Just to make sure that casting a ref to raw, to int and back to raw
-// and only then using it works. This rules out ideas like "do escape-to-raw lazily";
-// after casting to int and back, we lost the tag that could have let us do that.
-fn ref_raw_int_raw() {
-    let mut x = 3;
-    let xref = &mut x;
-    let xraw = xref as *mut i32 as usize as *mut i32;
-    assert_eq!(unsafe { *xraw }, 3);
-}
-
 // Escape a mut to raw, then share the same mut and use the share, then the raw.
 // That should work.
 fn mut_raw_then_mut_shr() {
@@ -162,3 +157,22 @@ fn disjoint_mutable_subborrows() {
     a.push_str(" world");
     eprintln!("{:?} {:?}", a, b);
 }
+
+fn raw_ref_to_part() {
+    struct Part {
+        _lame: i32,
+    }
+
+    #[repr(C)]
+    struct Whole {
+        part: Part,
+        extra: i32,
+    }
+
+    let it = Box::new(Whole { part: Part { _lame: 0 }, extra: 42 });
+    let whole = ptr::raw_mut!(*Box::leak(it));
+    let part = unsafe { ptr::raw_mut!((*whole).part) };
+    let typed = unsafe { &mut *(part as *mut Whole) };
+    assert!(typed.extra == 42);
+    drop(unsafe { Box::from_raw(whole) });
+}

tests/run-pass/thread-local.rs

@@ -58,7 +58,7 @@ fn main() {
         // Initialize the keys we use to check destructor ordering
         for (key, global) in KEYS.iter_mut().zip(GLOBALS.iter_mut()) {
             *key = create(Some(mem::transmute(dtor as unsafe extern fn(*mut u64))));
-            set(*key, global as *const _ as *mut _);
+            set(*key, global as *mut _ as *mut u8);
         }
 
         // Initialize cannary