Rollup merge of #82525 - RalfJung:unaligned-ref-warn, r=petrochenkov

make unaligned_references future-incompat lint warn-by-default

and also remove the safe_packed_borrows lint that it replaces.

`std::ptr::addr_of!` has hit beta now and will hit stable in a month, so I propose we start fixing https://github.com/rust-lang/rust/issues/27060 for real: creating a reference to a field of a packed struct needs to eventually become a hard error; this PR makes it a warn-by-default future-incompat lint. (The lint already existed, this just raises its default level.) At the same time I removed the corresponding code from unsafety checking; really there's no reason an `unsafe` block should make any difference here.

For references to packed fields outside `unsafe` blocks, this means `unaligned_refereces` replaces the previous `safe_packed_borrows` warning with a link to https://github.com/rust-lang/rust/issues/82523 (and no more talk about unsafe blocks making any difference). So behavior barely changes, the warning is just worded differently. For references to packed fields inside `unsafe` blocks, this PR shows a new future-incompat warning.

Closes https://github.com/rust-lang/rust/issues/46043 because that lint no longer exists.

25 files changed, 251 insertions, 415 deletions

diff --git a/compiler/rustc_lint/src/lib.rs b/compiler/rustc_lint/src/lib.rs
index cacdf260548..b547ee89387 100644
--- a/compiler/rustc_lint/src/lib.rs
+++ b/compiler/rustc_lint/src/lib.rs
@@ -325,6 +325,7 @@ fn register_builtins(store: &mut LintStore, no_interleave_lints: bool) {
     store.register_renamed("exceeding_bitshifts", "arithmetic_overflow");
     store.register_renamed("redundant_semicolon", "redundant_semicolons");
     store.register_renamed("overlapping_patterns", "overlapping_range_endpoints");
+    store.register_renamed("safe_packed_borrows", "unaligned_references");
 
     // These were moved to tool lints, but rustc still sees them when compiling normally, before
     // tool lints are registered, so `check_tool_name_for_backwards_compat` doesn't work. Use
diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
index cd4d01ddc05..3baafee4612 100644
--- a/compiler/rustc_lint_defs/src/builtin.rs
+++ b/compiler/rustc_lint_defs/src/builtin.rs
@@ -1057,6 +1057,7 @@ declare_lint! {
     ///     unsafe {
     ///         let foo = Foo { field1: 0, field2: 0 };
     ///         let _ = &foo.field1;
+    ///         println!("{}", foo.field1); // An implicit `&` is added here, triggering the lint.
     ///     }
     /// }
     /// ```
@@ -1065,20 +1066,20 @@ declare_lint! {
     ///
     /// ### Explanation
     ///
-    /// Creating a reference to an insufficiently aligned packed field is
-    /// [undefined behavior] and should be disallowed.
-    ///
-    /// This lint is "allow" by default because there is no stable
-    /// alternative, and it is not yet certain how widespread existing code
-    /// will trigger this lint.
-    ///
-    /// See [issue #27060] for more discussion.
+    /// Creating a reference to an insufficiently aligned packed field is [undefined behavior] and
+    /// should be disallowed. Using an `unsafe` block does not change anything about this. Instead,
+    /// the code should do a copy of the data in the packed field or use raw pointers and unaligned
+    /// accesses. See [issue #82523] for more information.
     ///
     /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
-    /// [issue #27060]: https://github.com/rust-lang/rust/issues/27060
+    /// [issue #82523]: https://github.com/rust-lang/rust/issues/82523
     pub UNALIGNED_REFERENCES,
-    Allow,
+    Warn,
     "detects unaligned references to fields of packed structs",
+    @future_incompatible = FutureIncompatibleInfo {
+        reference: "issue #82523 <https://github.com/rust-lang/rust/issues/82523>",
+        edition: None,
+    };
     report_in_external_macro
 }
 
@@ -1151,49 +1152,6 @@ declare_lint! {
 }
 
 declare_lint! {
-    /// The `safe_packed_borrows` lint detects borrowing a field in the
-    /// interior of a packed structure with alignment other than 1.
-    ///
-    /// ### Example
-    ///
-    /// ```rust
-    /// #[repr(packed)]
-    /// pub struct Unaligned<T>(pub T);
-    ///
-    /// pub struct Foo {
-    ///     start: u8,
-    ///     data: Unaligned<u32>,
-    /// }
-    ///
-    /// fn main() {
-    ///     let x = Foo { start: 0, data: Unaligned(1) };
-    ///     let y = &x.data.0;
-    /// }
-    /// ```
-    ///
-    /// {{produces}}
-    ///
-    /// ### Explanation
-    ///
-    /// This type of borrow is unsafe and can cause errors on some platforms
-    /// and violates some assumptions made by the compiler. This was
-    /// previously allowed unintentionally. This is a [future-incompatible]
-    /// lint to transition this to a hard error in the future. See [issue
-    /// #46043] for more details, including guidance on how to solve the
-    /// problem.
-    ///
-    /// [issue #46043]: https://github.com/rust-lang/rust/issues/46043
-    /// [future-incompatible]: ../index.md#future-incompatible-lints
-    pub SAFE_PACKED_BORROWS,
-    Warn,
-    "safe borrows of fields of packed structs were erroneously allowed",
-    @future_incompatible = FutureIncompatibleInfo {
-        reference: "issue #46043 <https://github.com/rust-lang/rust/issues/46043>",
-        edition: None,
-    };
-}
-
-declare_lint! {
     /// The `patterns_in_fns_without_body` lint detects `mut` identifier
     /// patterns as a parameter in functions without a body.
     ///
@@ -2953,7 +2911,6 @@ declare_lint_pass! {
         RENAMED_AND_REMOVED_LINTS,
         UNALIGNED_REFERENCES,
         CONST_ITEM_MUTATION,
-        SAFE_PACKED_BORROWS,
         PATTERNS_IN_FNS_WITHOUT_BODY,
         MISSING_FRAGMENT_SPECIFIER,
         LATE_BOUND_LIFETIME_ARGUMENTS,
diff --git a/compiler/rustc_middle/src/mir/query.rs b/compiler/rustc_middle/src/mir/query.rs
index bde48018013..ad3baccf154 100644
--- a/compiler/rustc_middle/src/mir/query.rs
+++ b/compiler/rustc_middle/src/mir/query.rs
@@ -23,15 +23,9 @@ pub enum UnsafetyViolationKind {
     General,
     /// Permitted both in `const fn`s and regular `fn`s.
     GeneralAndConstFn,
-    /// Borrow of packed field.
-    /// Has to be handled as a lint for backwards compatibility.
-    BorrowPacked,
     /// Unsafe operation in an `unsafe fn` but outside an `unsafe` block.
     /// Has to be handled as a lint for backwards compatibility.
     UnsafeFn,
-    /// Borrow of packed field in an `unsafe fn` but outside an `unsafe` block.
-    /// Has to be handled as a lint for backwards compatibility.
-    UnsafeFnBorrowPacked,
 }
 
 #[derive(Copy, Clone, PartialEq, TyEncodable, TyDecodable, HashStable, Debug)]
diff --git a/compiler/rustc_mir/src/transform/check_packed_ref.rs b/compiler/rustc_mir/src/transform/check_packed_ref.rs
index ee88daa83e7..13b7221046b 100644
--- a/compiler/rustc_mir/src/transform/check_packed_ref.rs
+++ b/compiler/rustc_mir/src/transform/check_packed_ref.rs
@@ -1,11 +1,18 @@
+use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_middle::mir::visit::{PlaceContext, Visitor};
 use rustc_middle::mir::*;
+use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::{self, TyCtxt};
 use rustc_session::lint::builtin::UNALIGNED_REFERENCES;
+use rustc_span::symbol::sym;
 
 use crate::transform::MirPass;
 use crate::util;
 
+pub(crate) fn provide(providers: &mut Providers) {
+    *providers = Providers { unsafe_derive_on_repr_packed, ..*providers };
+}
+
 pub struct CheckPackedRef;
 
 impl<'tcx> MirPass<'tcx> for CheckPackedRef {
@@ -24,6 +31,41 @@ struct PackedRefChecker<'a, 'tcx> {
     source_info: SourceInfo,
 }
 
+fn unsafe_derive_on_repr_packed(tcx: TyCtxt<'_>, def_id: LocalDefId) {
+    let lint_hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
+
+    tcx.struct_span_lint_hir(UNALIGNED_REFERENCES, lint_hir_id, tcx.def_span(def_id), |lint| {
+        // FIXME: when we make this a hard error, this should have its
+        // own error code.
+        let message = if tcx.generics_of(def_id).own_requires_monomorphization() {
+            "`#[derive]` can't be used on a `#[repr(packed)]` struct with \
+             type or const parameters (error E0133)"
+                .to_string()
+        } else {
+            "`#[derive]` can't be used on a `#[repr(packed)]` struct that \
+             does not derive Copy (error E0133)"
+                .to_string()
+        };
+        lint.build(&message).emit()
+    });
+}
+
+fn builtin_derive_def_id(tcx: TyCtxt<'_>, def_id: DefId) -> Option<DefId> {
+    debug!("builtin_derive_def_id({:?})", def_id);
+    if let Some(impl_def_id) = tcx.impl_of_method(def_id) {
+        if tcx.has_attr(impl_def_id, sym::automatically_derived) {
+            debug!("builtin_derive_def_id({:?}) - is {:?}", def_id, impl_def_id);
+            Some(impl_def_id)
+        } else {
+            debug!("builtin_derive_def_id({:?}) - not automatically derived", def_id);
+            None
+        }
+    } else {
+        debug!("builtin_derive_def_id({:?}) - not a method", def_id);
+        None
+    }
+}
+
 impl<'a, 'tcx> Visitor<'tcx> for PackedRefChecker<'a, 'tcx> {
     fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location) {
         // Make sure we know where in the MIR we are.
@@ -40,26 +82,33 @@ impl<'a, 'tcx> Visitor<'tcx> for PackedRefChecker<'a, 'tcx> {
     fn visit_place(&mut self, place: &Place<'tcx>, context: PlaceContext, _location: Location) {
         if context.is_borrow() {
             if util::is_disaligned(self.tcx, self.body, self.param_env, *place) {
-                let source_info = self.source_info;
-                let lint_root = self.body.source_scopes[source_info.scope]
-                    .local_data
-                    .as_ref()
-                    .assert_crate_local()
-                    .lint_root;
-                self.tcx.struct_span_lint_hir(
-                    UNALIGNED_REFERENCES,
-                    lint_root,
-                    source_info.span,
-                    |lint| {
-                        lint.build("reference to packed field is unaligned")
-                            .note(
-                                "fields of packed structs are not properly aligned, and creating \
-                                a misaligned reference is undefined behavior (even if that \
-                                reference is never dereferenced)",
-                            )
-                            .emit()
-                    },
-                );
+                let def_id = self.body.source.instance.def_id();
+                if let Some(impl_def_id) = builtin_derive_def_id(self.tcx, def_id) {
+                    // If a method is defined in the local crate,
+                    // the impl containing that method should also be.
+                    self.tcx.ensure().unsafe_derive_on_repr_packed(impl_def_id.expect_local());
+                } else {
+                    let source_info = self.source_info;
+                    let lint_root = self.body.source_scopes[source_info.scope]
+                        .local_data
+                        .as_ref()
+                        .assert_crate_local()
+                        .lint_root;
+                    self.tcx.struct_span_lint_hir(
+                        UNALIGNED_REFERENCES,
+                        lint_root,
+                        source_info.span,
+                        |lint| {
+                            lint.build("reference to packed field is unaligned")
+                                .note(
+                                    "fields of packed structs are not properly aligned, and creating \
+                                    a misaligned reference is undefined behavior (even if that \
+                                    reference is never dereferenced)",
+                                )
+                                .emit()
+                        },
+                    );
+                }
             }
         }
     }
diff --git a/compiler/rustc_mir/src/transform/check_unsafety.rs b/compiler/rustc_mir/src/transform/check_unsafety.rs
index 532d201e056..09da9b2e4d6 100644
--- a/compiler/rustc_mir/src/transform/check_unsafety.rs
+++ b/compiler/rustc_mir/src/transform/check_unsafety.rs
@@ -10,14 +10,12 @@ use rustc_middle::mir::*;
 use rustc_middle::ty::cast::CastTy;
 use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::{self, TyCtxt};
-use rustc_session::lint::builtin::{SAFE_PACKED_BORROWS, UNSAFE_OP_IN_UNSAFE_FN, UNUSED_UNSAFE};
+use rustc_session::lint::builtin::{UNSAFE_OP_IN_UNSAFE_FN, UNUSED_UNSAFE};
 use rustc_session::lint::Level;
-use rustc_span::symbol::sym;
 
 use std::ops::Bound;
 
 use crate::const_eval::is_min_const_fn;
-use crate::util;
 
 pub struct UnsafetyChecker<'a, 'tcx> {
     body: &'a Body<'tcx>,
@@ -182,18 +180,6 @@ impl<'a, 'tcx> Visitor<'tcx> for UnsafetyChecker<'a, 'tcx> {
             self.check_mut_borrowing_layout_constrained_field(*place, context.is_mutating_use());
         }
 
-        // Check for borrows to packed fields.
-        // `is_disaligned` already traverses the place to consider all projections after the last
-        // `Deref`, so this only needs to be called once at the top level.
-        if context.is_borrow() {
-            if util::is_disaligned(self.tcx, self.body, self.param_env, *place) {
-                self.require_unsafe(
-                    UnsafetyViolationKind::BorrowPacked,
-                    UnsafetyViolationDetails::BorrowOfPackedField,
-                );
-            }
-        }
-
         // Some checks below need the extra metainfo of the local declaration.
         let decl = &self.body.local_decls[place.local];
 
@@ -317,25 +303,15 @@ impl<'a, 'tcx> UnsafetyChecker<'a, 'tcx> {
             // `unsafe` blocks are required in safe code
             Safety::Safe => {
                 for violation in violations {
-                    let mut violation = *violation;
                     match violation.kind {
                         UnsafetyViolationKind::GeneralAndConstFn
                         | UnsafetyViolationKind::General => {}
-                        UnsafetyViolationKind::BorrowPacked => {
-                            if self.min_const_fn {
-                                // const fns don't need to be backwards compatible and can
-                                // emit these violations as a hard error instead of a backwards
-                                // compat lint
-                                violation.kind = UnsafetyViolationKind::General;
-                            }
-                        }
-                        UnsafetyViolationKind::UnsafeFn
-                        | UnsafetyViolationKind::UnsafeFnBorrowPacked => {
+                        UnsafetyViolationKind::UnsafeFn => {
                             bug!("`UnsafetyViolationKind::UnsafeFn` in an `Safe` context")
                         }
                     }
-                    if !self.violations.contains(&violation) {
-                        self.violations.push(violation)
+                    if !self.violations.contains(violation) {
+                        self.violations.push(*violation)
                     }
                 }
                 false
@@ -345,11 +321,7 @@ impl<'a, 'tcx> UnsafetyChecker<'a, 'tcx> {
                 for violation in violations {
                     let mut violation = *violation;
 
-                    if violation.kind == UnsafetyViolationKind::BorrowPacked {
-                        violation.kind = UnsafetyViolationKind::UnsafeFnBorrowPacked;
-                    } else {
-                        violation.kind = UnsafetyViolationKind::UnsafeFn;
-                    }
+                    violation.kind = UnsafetyViolationKind::UnsafeFn;
                     if !self.violations.contains(&violation) {
                         self.violations.push(violation)
                     }
@@ -369,8 +341,7 @@ impl<'a, 'tcx> UnsafetyChecker<'a, 'tcx> {
                             // these unsafe things are stable in const fn
                             UnsafetyViolationKind::GeneralAndConstFn => {}
                             // these things are forbidden in const fns
-                            UnsafetyViolationKind::General
-                            | UnsafetyViolationKind::BorrowPacked => {
+                            UnsafetyViolationKind::General => {
                                 let mut violation = *violation;
                                 // const fns don't need to be backwards compatible and can
                                 // emit these violations as a hard error instead of a backwards
@@ -380,8 +351,7 @@ impl<'a, 'tcx> UnsafetyChecker<'a, 'tcx> {
                                     self.violations.push(violation)
                                 }
                             }
-                            UnsafetyViolationKind::UnsafeFn
-                            | UnsafetyViolationKind::UnsafeFnBorrowPacked => bug!(
+                            UnsafetyViolationKind::UnsafeFn => bug!(
                                 "`UnsafetyViolationKind::UnsafeFn` in an `ExplicitUnsafe` context"
                             ),
                         }
@@ -464,7 +434,6 @@ pub(crate) fn provide(providers: &mut Providers) {
                 ty::WithOptConstParam { did, const_param_did: Some(param_did) },
             )
         },
-        unsafe_derive_on_repr_packed,
         ..*providers
     };
 }
@@ -544,25 +513,6 @@ fn unsafety_check_result<'tcx>(
     })
 }
 
-fn unsafe_derive_on_repr_packed(tcx: TyCtxt<'_>, def_id: LocalDefId) {
-    let lint_hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
-
-    tcx.struct_span_lint_hir(SAFE_PACKED_BORROWS, lint_hir_id, tcx.def_span(def_id), |lint| {
-        // FIXME: when we make this a hard error, this should have its
-        // own error code.
-        let message = if tcx.generics_of(def_id).own_requires_monomorphization() {
-            "`#[derive]` can't be used on a `#[repr(packed)]` struct with \
-             type or const parameters (error E0133)"
-                .to_string()
-        } else {
-            "`#[derive]` can't be used on a `#[repr(packed)]` struct that \
-             does not derive Copy (error E0133)"
-                .to_string()
-        };
-        lint.build(&message).emit()
-    });
-}
-
 /// Returns the `HirId` for an enclosing scope that is also `unsafe`.
 fn is_enclosed(
     tcx: TyCtxt<'_>,
@@ -609,22 +559,6 @@ fn report_unused_unsafe(tcx: TyCtxt<'_>, used_unsafe: &FxHashSet<hir::HirId>, id
     });
 }
 
-fn builtin_derive_def_id(tcx: TyCtxt<'_>, def_id: DefId) -> Option<DefId> {
-    debug!("builtin_derive_def_id({:?})", def_id);
-    if let Some(impl_def_id) = tcx.impl_of_method(def_id) {
-        if tcx.has_attr(impl_def_id, sym::automatically_derived) {
-            debug!("builtin_derive_def_id({:?}) - is {:?}", def_id, impl_def_id);
-            Some(impl_def_id)
-        } else {
-            debug!("builtin_derive_def_id({:?}) - not automatically derived", def_id);
-            None
-        }
-    } else {
-        debug!("builtin_derive_def_id({:?}) - not a method", def_id);
-        None
-    }
-}
-
 pub fn check_unsafety(tcx: TyCtxt<'_>, def_id: LocalDefId) {
     debug!("check_unsafety({:?})", def_id);
 
@@ -657,27 +591,6 @@ pub fn check_unsafety(tcx: TyCtxt<'_>, def_id: LocalDefId) {
                 .note(note)
                 .emit();
             }
-            UnsafetyViolationKind::BorrowPacked => {
-                if let Some(impl_def_id) = builtin_derive_def_id(tcx, def_id.to_def_id()) {
-                    // If a method is defined in the local crate,
-                    // the impl containing that method should also be.
-                    tcx.ensure().unsafe_derive_on_repr_packed(impl_def_id.expect_local());
-                } else {
-                    tcx.struct_span_lint_hir(
-                        SAFE_PACKED_BORROWS,
-                        lint_root,
-                        source_info.span,
-                        |lint| {
-                            lint.build(&format!(
-                                "{} is unsafe and requires unsafe{} block (error E0133)",
-                                description, unsafe_fn_msg,
-                            ))
-                            .note(note)
-                            .emit()
-                        },
-                    )
-                }
-            }
             UnsafetyViolationKind::UnsafeFn => tcx.struct_span_lint_hir(
                 UNSAFE_OP_IN_UNSAFE_FN,
                 lint_root,
@@ -692,35 +605,6 @@ pub fn check_unsafety(tcx: TyCtxt<'_>, def_id: LocalDefId) {
                     .emit();
                 },
             ),
-            UnsafetyViolationKind::UnsafeFnBorrowPacked => {
-                // When `unsafe_op_in_unsafe_fn` is disallowed, the behavior of safe and unsafe functions
-                // should be the same in terms of warnings and errors. Therefore, with `#[warn(safe_packed_borrows)]`,
-                // a safe packed borrow should emit a warning *but not an error* in an unsafe function,
-                // just like in a safe function, even if `unsafe_op_in_unsafe_fn` is `deny`.
-                //
-                // Also, `#[warn(unsafe_op_in_unsafe_fn)]` can't cause any new errors. Therefore, with
-                // `#[deny(safe_packed_borrows)]` and `#[warn(unsafe_op_in_unsafe_fn)]`, a packed borrow
-                // should only issue a warning for the sake of backwards compatibility.
-                //
-                // The solution those 2 expectations is to always take the minimum of both lints.
-                // This prevent any new errors (unless both lints are explicitly set to `deny`).
-                let lint = if tcx.lint_level_at_node(SAFE_PACKED_BORROWS, lint_root).0
-                    <= tcx.lint_level_at_node(UNSAFE_OP_IN_UNSAFE_FN, lint_root).0
-                {
-                    SAFE_PACKED_BORROWS
-                } else {
-                    UNSAFE_OP_IN_UNSAFE_FN
-                };
-                tcx.struct_span_lint_hir(&lint, lint_root, source_info.span, |lint| {
-                    lint.build(&format!(
-                        "{} is unsafe and requires unsafe block (error E0133)",
-                        description,
-                    ))
-                    .span_label(source_info.span, description)
-                    .note(note)
-                    .emit();
-                })
-            }
         }
     }
 
diff --git a/compiler/rustc_mir/src/transform/mod.rs b/compiler/rustc_mir/src/transform/mod.rs
index 66d2ab8a3f1..5c49ee69edc 100644
--- a/compiler/rustc_mir/src/transform/mod.rs
+++ b/compiler/rustc_mir/src/transform/mod.rs
@@ -59,6 +59,7 @@ pub use rustc_middle::mir::MirSource;
 
 pub(crate) fn provide(providers: &mut Providers) {
     self::check_unsafety::provide(providers);
+    self::check_packed_ref::provide(providers);
     *providers = Providers {
         mir_keys,
         mir_const,
diff --git a/library/core/src/ptr/mod.rs b/library/core/src/ptr/mod.rs
index 7e4f8d570a7..2392f0174b6 100644
--- a/library/core/src/ptr/mod.rs
+++ b/library/core/src/ptr/mod.rs
@@ -767,6 +767,7 @@ pub const unsafe fn read<T>(src: *const T) -> T {
 ///     unaligned: 0x01020304,
 /// };
 ///
+/// #[allow(unaligned_references)]
 /// let v = unsafe {
 ///     // Here we attempt to take the address of a 32-bit integer which is not aligned.
 ///     let unaligned =
@@ -960,6 +961,7 @@ pub const unsafe fn write<T>(dst: *mut T, src: T) {
 /// let v = 0x01020304;
 /// let mut packed: Packed = unsafe { std::mem::zeroed() };
 ///
+/// #[allow(unaligned_references)]
 /// let v = unsafe {
 ///     // Here we attempt to take the address of a 32-bit integer which is not aligned.
 ///     let unaligned =
diff --git a/src/test/ui/binding/issue-53114-safety-checks.rs b/src/test/ui/binding/issue-53114-safety-checks.rs
index 28adb7571a9..ca4f0efd239 100644
--- a/src/test/ui/binding/issue-53114-safety-checks.rs
+++ b/src/test/ui/binding/issue-53114-safety-checks.rs
@@ -20,13 +20,13 @@ fn let_wild_gets_unsafe_field() {
     let u1 = U { a: I(0) };
     let u2 = U { a: I(1) };
     let p = P { a: &2, b: &3 };
-    let _ = &p.b;  //~ WARN    E0133
+    let _ = &p.b;  //~ WARN    reference to packed field
     //~^  WARN will become a hard error
     let _ = u1.a;  // #53114: should eventually signal error as well
     let _ = &u2.a; //~ ERROR  [E0133]
 
     // variation on above with `_` in substructure
-    let (_,) = (&p.b,);  //~ WARN     E0133
+    let (_,) = (&p.b,);  //~ WARN     reference to packed field
     //~^  WARN will become a hard error
     let (_,) = (u1.a,);  //~ ERROR   [E0133]
     let (_,) = (&u2.a,); //~ ERROR   [E0133]
@@ -36,13 +36,13 @@ fn match_unsafe_field_to_wild() {
     let u1 = U { a: I(0) };
     let u2 = U { a: I(1) };
     let p = P { a: &2, b: &3 };
-    match &p.b  { _ => { } } //~ WARN     E0133
+    match &p.b  { _ => { } } //~ WARN     reference to packed field
     //~^  WARN will become a hard error
     match u1.a  { _ => { } } //~ ERROR   [E0133]
     match &u2.a { _ => { } } //~ ERROR   [E0133]
 
     // variation on above with `_` in substructure
-    match (&p.b,)  { (_,) => { } } //~ WARN     E0133
+    match (&p.b,)  { (_,) => { } } //~ WARN     reference to packed field
     //~^  WARN will become a hard error
     match (u1.a,)  { (_,) => { } } //~ ERROR   [E0133]
     match (&u2.a,) { (_,) => { } } //~ ERROR   [E0133]
diff --git a/src/test/ui/binding/issue-53114-safety-checks.stderr b/src/test/ui/binding/issue-53114-safety-checks.stderr
index d4b8dfbade5..9e7deea4524 100644
--- a/src/test/ui/binding/issue-53114-safety-checks.stderr
+++ b/src/test/ui/binding/issue-53114-safety-checks.stderr
@@ -1,13 +1,43 @@
-warning: borrow of packed field is unsafe and requires unsafe function or block (error E0133)
+warning: reference to packed field is unaligned
   --> $DIR/issue-53114-safety-checks.rs:23:13
    |
 LL |     let _ = &p.b;
    |             ^^^^
    |
-   = note: `#[warn(safe_packed_borrows)]` on by default
+   = note: `#[warn(unaligned_references)]` on by default
    = 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 #46043 <https://github.com/rust-lang/rust/issues/46043>
-   = note: fields of packed structs might be misaligned: dereferencing a misaligned pointer or even just creating a misaligned reference is undefined behavior
+   = 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)
+
+warning: reference to packed field is unaligned
+  --> $DIR/issue-53114-safety-checks.rs:29:17
+   |
+LL |     let (_,) = (&p.b,);
+   |                 ^^^^
+   |
+   = 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)
+
+warning: reference to packed field is unaligned
+  --> $DIR/issue-53114-safety-checks.rs:39:11
+   |
+LL |     match &p.b  { _ => { } }
+   |           ^^^^
+   |
+   = 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)
+
+warning: reference to packed field is unaligned
+  --> $DIR/issue-53114-safety-checks.rs:45:12
+   |
+LL |     match (&p.b,)  { (_,) => { } }
+   |            ^^^^
+   |
+   = 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[E0133]: access to union field is unsafe and requires unsafe function or block
   --> $DIR/issue-53114-safety-checks.rs:26:13
@@ -17,16 +47,6 @@ LL |     let _ = &u2.a;
    |
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
-warning: borrow of packed field is unsafe and requires unsafe function or block (error E0133)
-  --> $DIR/issue-53114-safety-checks.rs:29:17
-   |
-LL |     let (_,) = (&p.b,);
-   |                 ^^^^
-   |
-   = 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 #46043 <https://github.com/rust-lang/rust/issues/46043>
-   = note: fields of packed structs might be misaligned: dereferencing a misaligned pointer or even just creating a misaligned reference is undefined behavior
-
 error[E0133]: access to union field is unsafe and requires unsafe function or block
   --> $DIR/issue-53114-safety-checks.rs:31:17
    |
@@ -43,16 +63,6 @@ LL |     let (_,) = (&u2.a,);
    |
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
-warning: borrow of packed field is unsafe and requires unsafe function or block (error E0133)
-  --> $DIR/issue-53114-safety-checks.rs:39:11
-   |
-LL |     match &p.b  { _ => { } }
-   |           ^^^^
-   |
-   = 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 #46043 <https://github.com/rust-lang/rust/issues/46043>
-   = note: fields of packed structs might be misaligned: dereferencing a misaligned pointer or even just creating a misaligned reference is undefined behavior
-
 error[E0133]: access to union field is unsafe and requires unsafe function or block
   --> $DIR/issue-53114-safety-checks.rs:41:11
    |
@@ -69,16 +79,6 @@ LL |     match &u2.a { _ => { } }
    |
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
-warning: borrow of packed field is unsafe and requires unsafe function or block (error E0133)
-  --> $DIR/issue-53114-safety-checks.rs:45:12
-   |
-LL |     match (&p.b,)  { (_,) => { } }
-   |            ^^^^
-   |
-   = 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 #46043 <https://github.com/rust-lang/rust/issues/46043>
-   = note: fields of packed structs might be misaligned: dereferencing a misaligned pointer or even just creating a misaligned reference is undefined behavior
-
 error[E0133]: access to union field is unsafe and requires unsafe function or block
   --> $DIR/issue-53114-safety-checks.rs:47:12
    |
diff --git a/src/test/ui/closures/2229_closure_analysis/diagnostics/repr_packed.rs b/src/test/ui/closures/2229_closure_analysis/diagnostics/repr_packed.rs
index 6fce2951505..82ec60a2e79 100644
--- a/src/test/ui/closures/2229_closure_analysis/diagnostics/repr_packed.rs
+++ b/src/test/ui/closures/2229_closure_analysis/diagnostics/repr_packed.rs
@@ -23,7 +23,7 @@ fn test_missing_unsafe_warning_on_repr_packed() {
 
     let c = || {
         println!("{}", foo.x);
-        //~^ WARNING: borrow of packed field is unsafe and requires unsafe function or block
+        //~^ WARNING: reference to packed field is unaligned
         //~| WARNING: this was previously accepted by the compiler but is being phased out
         let _z = foo.x;
     };
diff --git a/src/test/ui/closures/2229_closure_analysis/diagnostics/repr_packed.stderr b/src/test/ui/closures/2229_closure_analysis/diagnostics/repr_packed.stderr
index 440b2c54c0a..e8cc164be87 100644
--- a/src/test/ui/closures/2229_closure_analysis/diagnostics/repr_packed.stderr
+++ b/src/test/ui/closures/2229_closure_analysis/diagnostics/repr_packed.stderr
@@ -7,16 +7,16 @@ LL | #![feature(capture_disjoint_fields)]
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #53488 <https://github.com/rust-lang/rust/issues/53488> for more information
 
-warning: borrow of packed field is unsafe and requires unsafe function or block (error E0133)
+warning: reference to packed field is unaligned
   --> $DIR/repr_packed.rs:25:24
    |
 LL |         println!("{}", foo.x);
    |                        ^^^^^
    |
-   = note: `#[warn(safe_packed_borrows)]` on by default
+   = note: `#[warn(unaligned_references)]` on by default
    = 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 #46043 <https://github.com/rust-lang/rust/issues/46043>
-   = note: fields of packed structs might be misaligned: dereferencing a misaligned pointer or even just creating a misaligned reference is undefined behavior
+   = 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)
 
 warning: 2 warnings emitted
 
diff --git a/src/test/ui/derives/deriving-with-repr-packed.rs b/src/test/ui/derives/deriving-with-repr-packed.rs
index d354cef66bc..b78eeaa9055 100644
--- a/src/test/ui/derives/deriving-with-repr-packed.rs
+++ b/src/test/ui/derives/deriving-with-repr-packed.rs
@@ -1,4 +1,4 @@
-#![deny(safe_packed_borrows)]
+#![deny(unaligned_references)]
 
 // check that derive on a packed struct with non-Copy fields
 // correctly. This can't be made to work perfectly because
diff --git a/src/test/ui/derives/deriving-with-repr-packed.stderr b/src/test/ui/derives/deriving-with-repr-packed.stderr
index d739257c8de..3caa563a085 100644
--- a/src/test/ui/derives/deriving-with-repr-packed.stderr
+++ b/src/test/ui/derives/deriving-with-repr-packed.stderr
@@ -7,10 +7,10 @@ LL | #[derive(Copy, Clone, PartialEq, Eq)]
 note: the lint level is defined here
   --> $DIR/deriving-with-repr-packed.rs:1:9
    |
-LL | #![deny(safe_packed_borrows)]
-   |         ^^^^^^^^^^^^^^^^^^^
+LL | #![deny(unaligned_references)]
+   |         ^^^^^^^^^^^^^^^^^^^^
    = 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 #46043 <https://github.com/rust-lang/rust/issues/46043>
+   = note: for more information, see issue #82523 <https://github.com/rust-lang/rust/issues/82523>
    = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: `#[derive]` can't be used on a `#[repr(packed)]` struct with type or const parameters (error E0133)
@@ -20,7 +20,7 @@ LL | #[derive(Copy, Clone, PartialEq, Eq)]
    |                       ^^^^^^^^^
    |
    = 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 #46043 <https://github.com/rust-lang/rust/issues/46043>
+   = note: for more information, see issue #82523 <https://github.com/rust-lang/rust/issues/82523>
    = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: `#[derive]` can't be used on a `#[repr(packed)]` struct that does not derive Copy (error E0133)
@@ -30,7 +30,7 @@ LL | #[derive(PartialEq, Eq)]
    |          ^^^^^^^^^
    |
    = 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 #46043 <https://github.com/rust-lang/rust/issues/46043>
+   = note: for more information, see issue #82523 <https://github.com/rust-lang/rust/issues/82523>
    = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: `#[derive]` can't be used on a `#[repr(packed)]` struct that does not derive Copy (error E0133)
@@ -40,7 +40,7 @@ LL | #[derive(PartialEq)]
    |          ^^^^^^^^^
    |
    = 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 #46043 <https://github.com/rust-lang/rust/issues/46043>
+   = note: for more information, see issue #82523 <https://github.com/rust-lang/rust/issues/82523>
    = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to 4 previous errors
diff --git a/src/test/ui/issues/issue-27060-rpass.rs b/src/test/ui/issues/issue-27060-rpass.rs
index b20d614b303..d9159f6669d 100644
--- a/src/test/ui/issues/issue-27060-rpass.rs
+++ b/src/test/ui/issues/issue-27060-rpass.rs
@@ -8,14 +8,12 @@ pub struct Good {
 }
 
 // kill this test when that turns to a hard error
-#[allow(safe_packed_borrows)]
+#[allow(unaligned_references)]
 fn main() {
     let good = Good { data: &0, data2: [&0, &0], aligned: [0; 32] };
 
-    unsafe {
-        let _ = &good.data; // ok
-        let _ = &good.data2[0]; // ok
-    }
+    let _ = &good.data; // ok
+    let _ = &good.data2[0]; // ok
 
     let _ = &good.data;
     let _ = &good.data2[0];
diff --git a/src/test/ui/issues/issue-27060.rs b/src/test/ui/issues/issue-27060.rs
index 78f2022ed38..5317a616719 100644
--- a/src/test/ui/issues/issue-27060.rs
+++ b/src/test/ui/issues/issue-27060.rs
@@ -5,7 +5,7 @@ pub struct Good {
     aligned: [u8; 32],
 }
 
-#[deny(safe_packed_borrows)]
+#[deny(unaligned_references)]
 fn main() {
     let good = Good {
         data: &0,
@@ -13,14 +13,14 @@ fn main() {
         aligned: [0; 32]
     };
 
-    unsafe {
-        let _ = &good.data; // ok
-        let _ = &good.data2[0]; // ok
-    }
+    let _ = &good.data; //~ ERROR reference to packed field
+    //~| hard error
+    let _ = &good.data2[0]; //~ ERROR reference to packed field
+    //~| hard error
 
-    let _ = &good.data; //~ ERROR borrow of packed field is unsafe
+    let _ = &good.data; //~ ERROR reference to packed field
                         //~| hard error
-    let _ = &good.data2[0]; //~ ERROR borrow of packed field is unsafe
+    let _ = &good.data2[0]; //~ ERROR reference to packed field
                             //~| hard error
     let _ = &*good.data; // ok, behind a pointer
     let _ = &good.aligned; // ok, has align 1
diff --git a/src/test/ui/issues/issue-27060.stderr b/src/test/ui/issues/issue-27060.stderr
index d14ae4d41d5..09297884ed3 100644
--- a/src/test/ui/issues/issue-27060.stderr
+++ b/src/test/ui/issues/issue-27060.stderr
@@ -1,5 +1,5 @@
-error: borrow of packed field is unsafe and requires unsafe function or block (error E0133)
-  --> $DIR/issue-27060.rs:21:13
+error: reference to packed field is unaligned
+  --> $DIR/issue-27060.rs:16:13
    |
 LL |     let _ = &good.data;
    |             ^^^^^^^^^^
@@ -7,21 +7,41 @@ LL |     let _ = &good.data;
 note: the lint level is defined here
   --> $DIR/issue-27060.rs:8:8
    |
-LL | #[deny(safe_packed_borrows)]
-   |        ^^^^^^^^^^^^^^^^^^^
+LL | #[deny(unaligned_references)]
+   |        ^^^^^^^^^^^^^^^^^^^^
+   = 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: reference to packed field is unaligned
+  --> $DIR/issue-27060.rs:18:13
+   |
+LL |     let _ = &good.data2[0];
+   |             ^^^^^^^^^^^^^^
+   |
+   = 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: reference to packed field is unaligned
+  --> $DIR/issue-27060.rs:21:13
+   |
+LL |     let _ = &good.data;
+   |             ^^^^^^^^^^
+   |
    = 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 #46043 <https://github.com/rust-lang/rust/issues/46043>
-   = note: fields of packed structs might be misaligned: dereferencing a misaligned pointer or even just creating a misaligned reference is undefined behavior
+   = 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: borrow of packed field is unsafe and requires unsafe function or block (error E0133)
+error: reference to packed field is unaligned
   --> $DIR/issue-27060.rs:23:13
    |
 LL |     let _ = &good.data2[0];
    |             ^^^^^^^^^^^^^^
    |
    = 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 #46043 <https://github.com/rust-lang/rust/issues/46043>
-   = note: fields of packed structs might be misaligned: dereferencing a misaligned pointer or even just creating a misaligned reference is undefined behavior
+   = 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 2 previous errors
+error: aborting due to 4 previous errors
 
diff --git a/src/test/ui/lint/unaligned_references.rs b/src/test/ui/lint/unaligned_references.rs
index c4e5d065643..ad38c21d96c 100644
--- a/src/test/ui/lint/unaligned_references.rs
+++ b/src/test/ui/lint/unaligned_references.rs
@@ -13,14 +13,20 @@ fn main() {
         let good = Good { data: 0, ptr: &0, data2: [0, 0], aligned: [0; 32] };
 
         let _ = &good.ptr; //~ ERROR reference to packed field
+        //~^ previously accepted
         let _ = &good.data; //~ ERROR reference to packed field
+        //~^ previously accepted
         // Error even when turned into raw pointer immediately.
         let _ = &good.data as *const _; //~ ERROR reference to packed field
+        //~^ previously accepted
         let _: *const _ = &good.data; //~ ERROR reference to packed field
+        //~^ previously accepted
         // Error on method call.
         let _ = good.data.clone(); //~ ERROR reference to packed field
+        //~^ previously accepted
         // Error for nested fields.
         let _ = &good.data2[0]; //~ ERROR reference to packed field
+        //~^ previously accepted
 
         let _ = &*good.ptr; // ok, behind a pointer
         let _ = &good.aligned; // ok, has align 1
diff --git a/src/test/ui/lint/unaligned_references.stderr b/src/test/ui/lint/unaligned_references.stderr
index 8786b9c05db..9ae25f5b59e 100644
--- a/src/test/ui/lint/unaligned_references.stderr
+++ b/src/test/ui/lint/unaligned_references.stderr
@@ -9,46 +9,58 @@ note: the lint level is defined here
    |
 LL | #![deny(unaligned_references)]
    |         ^^^^^^^^^^^^^^^^^^^^
+   = 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: reference to packed field is unaligned
-  --> $DIR/unaligned_references.rs:16:17
+  --> $DIR/unaligned_references.rs:17:17
    |
 LL |         let _ = &good.data;
    |                 ^^^^^^^^^^
    |
+   = 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: reference to packed field is unaligned
-  --> $DIR/unaligned_references.rs:18:17
+  --> $DIR/unaligned_references.rs:20:17
    |
 LL |         let _ = &good.data as *const _;
    |                 ^^^^^^^^^^
    |
+   = 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: reference to packed field is unaligned
-  --> $DIR/unaligned_references.rs:19:27
+  --> $DIR/unaligned_references.rs:22:27
    |
 LL |         let _: *const _ = &good.data;
    |                           ^^^^^^^^^^
    |
+   = 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: reference to packed field is unaligned
-  --> $DIR/unaligned_references.rs:21:17
+  --> $DIR/unaligned_references.rs:25:17
    |
 LL |         let _ = good.data.clone();
    |                 ^^^^^^^^^
    |
+   = 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: reference to packed field is unaligned
-  --> $DIR/unaligned_references.rs:23:17
+  --> $DIR/unaligned_references.rs:28:17
    |
 LL |         let _ = &good.data2[0];
    |                 ^^^^^^^^^^^^^^
    |
+   = 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 6 previous errors
diff --git a/src/test/ui/lint/unaligned_references_external_macro.rs b/src/test/ui/lint/unaligned_references_external_macro.rs
index 6ac501fb0e0..cb597c38e77 100644
--- a/src/test/ui/lint/unaligned_references_external_macro.rs
+++ b/src/test/ui/lint/unaligned_references_external_macro.rs
@@ -1,10 +1,9 @@
 // aux-build:unaligned_references_external_crate.rs
 
-#![allow(safe_packed_borrows)]
-
 extern crate unaligned_references_external_crate;
 
 unaligned_references_external_crate::mac! { //~ERROR reference to packed field is unaligned
+    //~^ previously accepted
     #[repr(packed)]
     pub struct X {
         pub field: u16
diff --git a/src/test/ui/lint/unaligned_references_external_macro.stderr b/src/test/ui/lint/unaligned_references_external_macro.stderr
index 140294b65cc..4e7c6bfc98d 100644
--- a/src/test/ui/lint/unaligned_references_external_macro.stderr
+++ b/src/test/ui/lint/unaligned_references_external_macro.stderr
@@ -1,7 +1,8 @@
 error: reference to packed field is unaligned
-  --> $DIR/unaligned_references_external_macro.rs:7:1
+  --> $DIR/unaligned_references_external_macro.rs:5:1
    |
 LL | / unaligned_references_external_crate::mac! {
+LL | |
 LL | |     #[repr(packed)]
 LL | |     pub struct X {
 LL | |         pub field: u16
@@ -10,15 +11,18 @@ LL | | }
    | |_^
    |
 note: the lint level is defined here
-  --> $DIR/unaligned_references_external_macro.rs:7:1
+  --> $DIR/unaligned_references_external_macro.rs:5:1
    |
 LL | / unaligned_references_external_crate::mac! {
+LL | |
 LL | |     #[repr(packed)]
 LL | |     pub struct X {
 LL | |         pub field: u16
 LL | |     }
 LL | | }
    | |_^
+   = 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)
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
diff --git a/src/test/ui/packed/packed-struct-address-of-element.rs b/src/test/ui/packed/packed-struct-address-of-element.rs
index 812d23fb580..fb3875e6804 100644
--- a/src/test/ui/packed/packed-struct-address-of-element.rs
+++ b/src/test/ui/packed/packed-struct-address-of-element.rs
@@ -1,6 +1,6 @@
 // run-pass
 #![allow(dead_code)]
-#![deny(safe_packed_borrows)]
+#![deny(unaligned_references)]
 #![feature(raw_ref_op)]
 // ignore-emscripten weird assertion?
 
diff --git a/src/test/ui/packed/packed-struct-borrow-element.rs b/src/test/ui/packed/packed-struct-borrow-element.rs
index 0072b6191eb..5dad084eecf 100644
--- a/src/test/ui/packed/packed-struct-borrow-element.rs
+++ b/src/test/ui/packed/packed-struct-borrow-element.rs
@@ -22,14 +22,17 @@ struct Foo4C {
 
 pub fn main() {
     let foo = Foo1 { bar: 1, baz: 2 };
-    let brw = unsafe { &foo.baz };
+    let brw = &foo.baz; //~WARN reference to packed field is unaligned
+    //~^ previously accepted
     assert_eq!(*brw, 2);
 
     let foo = Foo2 { bar: 1, baz: 2 };
-    let brw = unsafe { &foo.baz };
+    let brw = &foo.baz; //~WARN reference to packed field is unaligned
+    //~^ previously accepted
     assert_eq!(*brw, 2);
 
     let foo = Foo4C { bar: 1, baz: 2 };
-    let brw = unsafe { &foo.baz };
+    let brw = &foo.baz; //~WARN reference to packed field is unaligned
+    //~^ previously accepted
     assert_eq!(*brw, 2);
 }
diff --git a/src/test/ui/packed/packed-struct-borrow-element.stderr b/src/test/ui/packed/packed-struct-borrow-element.stderr
new file mode 100644
index 00000000000..d9d9a71ff58
--- /dev/null
+++ b/src/test/ui/packed/packed-struct-borrow-element.stderr
@@ -0,0 +1,33 @@
+warning: reference to packed field is unaligned
+  --> $DIR/packed-struct-borrow-element.rs:25:15
+   |
+LL |     let brw = &foo.baz;
+   |               ^^^^^^^^
+   |
+   = note: `#[warn(unaligned_references)]` on by default
+   = 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)
+
+warning: reference to packed field is unaligned
+  --> $DIR/packed-struct-borrow-element.rs:30:15
+   |
+LL |     let brw = &foo.baz;
+   |               ^^^^^^^^
+   |
+   = 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)
+
+warning: reference to packed field is unaligned
+  --> $DIR/packed-struct-borrow-element.rs:35:15
+   |
+LL |     let brw = &foo.baz;
+   |               ^^^^^^^^
+   |
+   = 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)
+
+warning: 3 warnings emitted
+
diff --git a/src/test/ui/unsafe/rfc-2585-safe_packed_borrows-in-unsafe-fn.rs b/src/test/ui/unsafe/rfc-2585-safe_packed_borrows-in-unsafe-fn.rs
deleted file mode 100644
index 540612a7dce..00000000000
--- a/src/test/ui/unsafe/rfc-2585-safe_packed_borrows-in-unsafe-fn.rs
+++ /dev/null
@@ -1,67 +0,0 @@
-#![feature(unsafe_block_in_unsafe_fn)]
-
-#[repr(packed)]
-pub struct Packed {
-    data: &'static u32,
-}
-
-const PACKED: Packed = Packed { data: &0 };
-
-#[allow(safe_packed_borrows)]
-#[allow(unsafe_op_in_unsafe_fn)]
-unsafe fn allow_allow() {
-    &PACKED.data; // allowed
-}
-
-#[allow(safe_packed_borrows)]
-#[warn(unsafe_op_in_unsafe_fn)]
-unsafe fn allow_warn() {
-    &PACKED.data; // allowed
-}
-
-#[allow(safe_packed_borrows)]
-#[deny(unsafe_op_in_unsafe_fn)]
-unsafe fn allow_deny() {
-    &PACKED.data; // allowed
-}
-
-#[warn(safe_packed_borrows)]
-#[allow(unsafe_op_in_unsafe_fn)]
-unsafe fn warn_allow() {
-    &PACKED.data; // allowed
-}
-
-#[warn(safe_packed_borrows)]
-#[warn(unsafe_op_in_unsafe_fn)]
-unsafe fn warn_warn() {
-    &PACKED.data; //~ WARN
-    //~| WARNING this was previously accepted by the compiler but is being phased out
-}
-
-#[warn(safe_packed_borrows)]
-#[deny(unsafe_op_in_unsafe_fn)]
-unsafe fn warn_deny() {
-    &PACKED.data; //~ WARN
-    //~| WARNING this was previously accepted by the compiler but is being phased out
-}
-
-#[deny(safe_packed_borrows)]
-#[allow(unsafe_op_in_unsafe_fn)]
-unsafe fn deny_allow() {
-    &PACKED.data; // allowed
-}
-
-#[deny(safe_packed_borrows)]
-#[warn(unsafe_op_in_unsafe_fn)]
-unsafe fn deny_warn() {
-    &PACKED.data; //~ WARN
-}
-
-#[deny(safe_packed_borrows)]
-#[deny(unsafe_op_in_unsafe_fn)]
-unsafe fn deny_deny() {
-    &PACKED.data; //~ ERROR
-    //~| WARNING this was previously accepted by the compiler but is being phased out
-}
-
-fn main() {}
diff --git a/src/test/ui/unsafe/rfc-2585-safe_packed_borrows-in-unsafe-fn.stderr b/src/test/ui/unsafe/rfc-2585-safe_packed_borrows-in-unsafe-fn.stderr
deleted file mode 100644
index fda15159643..00000000000
--- a/src/test/ui/unsafe/rfc-2585-safe_packed_borrows-in-unsafe-fn.stderr
+++ /dev/null
@@ -1,60 +0,0 @@
-warning: borrow of packed field is unsafe and requires unsafe block (error E0133)
-  --> $DIR/rfc-2585-safe_packed_borrows-in-unsafe-fn.rs:37:5
-   |
-LL |     &PACKED.data;
-   |     ^^^^^^^^^^^^ borrow of packed field
-   |
-note: the lint level is defined here
-  --> $DIR/rfc-2585-safe_packed_borrows-in-unsafe-fn.rs:34:8
-   |
-LL | #[warn(safe_packed_borrows)]
-   |        ^^^^^^^^^^^^^^^^^^^
-   = 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 #46043 <https://github.com/rust-lang/rust/issues/46043>
-   = note: fields of packed structs might be misaligned: dereferencing a misaligned pointer or even just creating a misaligned reference is undefined behavior
-
-warning: borrow of packed field is unsafe and requires unsafe block (error E0133)
-  --> $DIR/rfc-2585-safe_packed_borrows-in-unsafe-fn.rs:44:5
-   |
-LL |     &PACKED.data;
-   |     ^^^^^^^^^^^^ borrow of packed field
-   |
-note: the lint level is defined here
-  --> $DIR/rfc-2585-safe_packed_borrows-in-unsafe-fn.rs:41:8
-   |
-LL | #[warn(safe_packed_borrows)]
-   |        ^^^^^^^^^^^^^^^^^^^
-   = 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 #46043 <https://github.com/rust-lang/rust/issues/46043>
-   = note: fields of packed structs might be misaligned: dereferencing a misaligned pointer or even just creating a misaligned reference is undefined behavior
-
-warning: borrow of packed field is unsafe and requires unsafe block (error E0133)
-  --> $DIR/rfc-2585-safe_packed_borrows-in-unsafe-fn.rs:57:5
-   |
-LL |     &PACKED.data;
-   |     ^^^^^^^^^^^^ borrow of packed field
-   |
-note: the lint level is defined here
-  --> $DIR/rfc-2585-safe_packed_borrows-in-unsafe-fn.rs:55:8
-   |
-LL | #[warn(unsafe_op_in_unsafe_fn)]
-   |        ^^^^^^^^^^^^^^^^^^^^^^
-   = note: fields of packed structs might be misaligned: dereferencing a misaligned pointer or even just creating a misaligned reference is undefined behavior
-
-error: borrow of packed field is unsafe and requires unsafe block (error E0133)
-  --> $DIR/rfc-2585-safe_packed_borrows-in-unsafe-fn.rs:63:5
-   |
-LL |     &PACKED.data;
-   |     ^^^^^^^^^^^^ borrow of packed field
-   |
-note: the lint level is defined here
-  --> $DIR/rfc-2585-safe_packed_borrows-in-unsafe-fn.rs:60:8
-   |
-LL | #[deny(safe_packed_borrows)]
-   |        ^^^^^^^^^^^^^^^^^^^
-   = 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 #46043 <https://github.com/rust-lang/rust/issues/46043>
-   = note: fields of packed structs might be misaligned: dereferencing a misaligned pointer or even just creating a misaligned reference is undefined behavior
-
-error: aborting due to previous error; 3 warnings emitted
-