Merge #4743

4743: Add tracking of packed repr, use it to highlight unsafe refs r=matklad a=Nashenas88

Taking a reference to a misaligned field on a packed struct is an
unsafe operation. Highlight that behavior. Currently, the misaligned
part isn't tracked, so this highlight is a bit too aggressive.

Fixes #4600

Co-authored-by: Paul Daniel Faria <[email protected]>
Co-authored-by: Paul Daniel Faria <[email protected]>
Co-authored-by: Paul Daniel Faria <[email protected]>

1 files changed, 30 insertions, 3 deletions

diff --git a/crates/ra_ide/src/syntax_highlighting/tests.rs b/crates/ra_ide/src/syntax_highlighting/tests.rs
index 09062c38e..a8087635a 100644
--- a/crates/ra_ide/src/syntax_highlighting/tests.rs
+++ b/crates/ra_ide/src/syntax_highlighting/tests.rs
@@ -292,10 +292,24 @@ struct TypeForStaticMut {
 
 static mut global_mut: TypeForStaticMut = TypeForStaticMut { a: 0 };
 
+#[repr(packed)]
+struct Packed {
+    a: u16,
+}
+
+trait DoTheAutoref {
+    fn calls_autoref(&self);
+}
+
+impl DoTheAutoref for u16 {
+    fn calls_autoref(&self) {}
+}
+
 fn main() {
-    let x = &5 as *const usize;
+    let x = &5 as *const _ as *const usize;
     let u = Union { b: 0 };
     unsafe {
+        // unsafe fn and method calls
         unsafe_fn();
         let b = u.b;
         match u {
@@ -303,9 +317,22 @@ fn main() {
             Union { a } => (),
         }
         HasUnsafeFn.unsafe_method();
-        let y = *(x);
-        let z = -x;
+
+        // unsafe deref
+        let y = *x;
+
+        // unsafe access to a static mut
         let a = global_mut.a;
+
+        // unsafe ref of packed fields
+        let packed = Packed { a: 0 };
+        let a = &packed.a;
+        let ref a = packed.a;
+        let Packed { ref a } = packed;
+        let Packed { a: ref _a } = packed;
+
+        // unsafe auto ref of packed field
+        packed.a.calls_autoref();
     }
 }
 "#