unaligned_references: align(N) fields in packed(N) structs are fine

2 files changed, 32 insertions, 7 deletions

diff --git a/src/test/ui/lint/unaligned_references.rs b/src/test/ui/lint/unaligned_references.rs
index ad38c21d96c..d06b06b504f 100644
--- a/src/test/ui/lint/unaligned_references.rs
+++ b/src/test/ui/lint/unaligned_references.rs
@@ -8,6 +8,13 @@ pub struct Good {
     aligned: [u8; 32],
 }
 
+#[repr(packed(2))]
+pub struct Packed2 {
+    x: u32,
+    y: u16,
+    z: u8,
+}
+
 fn main() {
     unsafe {
         let good = Good { data: 0, ptr: &0, data2: [0, 0], aligned: [0; 32] };
@@ -32,4 +39,12 @@ fn main() {
         let _ = &good.aligned; // ok, has align 1
         let _ = &good.aligned[2]; // ok, has align 1
     }
+
+    unsafe {
+        let packed2 = Packed2 { x: 0, y: 0, z: 0 };
+        let _ = &packed2.x; //~ ERROR reference to packed field
+        //~^ previously accepted
+        let _ = &packed2.y; // ok, has align 2 in packed(2) struct
+        let _ = &packed2.z; // ok, has align 1
+    }
 }
diff --git a/src/test/ui/lint/unaligned_references.stderr b/src/test/ui/lint/unaligned_references.stderr
index 9ae25f5b59e..b4cce3cfea2 100644
--- a/src/test/ui/lint/unaligned_references.stderr
+++ b/src/test/ui/lint/unaligned_references.stderr
@@ -1,5 +1,5 @@
 error: reference to packed field is unaligned
-  --> $DIR/unaligned_references.rs:15:17
+  --> $DIR/unaligned_references.rs:22:17
    |
 LL |         let _ = &good.ptr;
    |                 ^^^^^^^^^
@@ -14,7 +14,7 @@ LL | #![deny(unaligned_references)]
    = note: fields of packed structs are not properly aligned, and creating a misaligned reference is undefined behavior (even if that reference is never dereferenced)
 
 error: reference to packed field is unaligned
-  --> $DIR/unaligned_references.rs:17:17
+  --> $DIR/unaligned_references.rs:24:17
    |
 LL |         let _ = &good.data;
    |                 ^^^^^^^^^^
@@ -24,7 +24,7 @@ LL |         let _ = &good.data;
    = note: fields of packed structs are not properly aligned, and creating a misaligned reference is undefined behavior (even if that reference is never dereferenced)
 
 error: reference to packed field is unaligned
-  --> $DIR/unaligned_references.rs:20:17
+  --> $DIR/unaligned_references.rs:27:17
    |
 LL |         let _ = &good.data as *const _;
    |                 ^^^^^^^^^^
@@ -34,7 +34,7 @@ LL |         let _ = &good.data as *const _;
    = note: fields of packed structs are not properly aligned, and creating a misaligned reference is undefined behavior (even if that reference is never dereferenced)
 
 error: reference to packed field is unaligned
-  --> $DIR/unaligned_references.rs:22:27
+  --> $DIR/unaligned_references.rs:29:27
    |
 LL |         let _: *const _ = &good.data;
    |                           ^^^^^^^^^^
@@ -44,7 +44,7 @@ LL |         let _: *const _ = &good.data;
    = note: fields of packed structs are not properly aligned, and creating a misaligned reference is undefined behavior (even if that reference is never dereferenced)
 
 error: reference to packed field is unaligned
-  --> $DIR/unaligned_references.rs:25:17
+  --> $DIR/unaligned_references.rs:32:17
    |
 LL |         let _ = good.data.clone();
    |                 ^^^^^^^^^
@@ -54,7 +54,7 @@ LL |         let _ = good.data.clone();
    = note: fields of packed structs are not properly aligned, and creating a misaligned reference is undefined behavior (even if that reference is never dereferenced)
 
 error: reference to packed field is unaligned
-  --> $DIR/unaligned_references.rs:28:17
+  --> $DIR/unaligned_references.rs:35:17
    |
 LL |         let _ = &good.data2[0];
    |                 ^^^^^^^^^^^^^^
@@ -63,5 +63,15 @@ LL |         let _ = &good.data2[0];
    = note: for more information, see issue #82523 <https://github.com/rust-lang/rust/issues/82523>
    = note: fields of packed structs are not properly aligned, and creating a misaligned reference is undefined behavior (even if that reference is never dereferenced)
 
-error: aborting due to 6 previous errors
+error: reference to packed field is unaligned
+  --> $DIR/unaligned_references.rs:45:17
+   |
+LL |         let _ = &packed2.x;
+   |                 ^^^^^^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #82523 <https://github.com/rust-lang/rust/issues/82523>
+   = note: fields of packed structs are not properly aligned, and creating a misaligned reference is undefined behavior (even if that reference is never dereferenced)
+
+error: aborting due to 7 previous errors