diff --git a/compiler/rustc_mir_transform/src/check_packed_ref.rs b/compiler/rustc_mir_transform/src/check_packed_ref.rs index f5f1c1010e1..b9bc89fcf8f 100644 --- a/compiler/rustc_mir_transform/src/check_packed_ref.rs +++ b/compiler/rustc_mir_transform/src/check_packed_ref.rs @@ -56,8 +56,11 @@ impl<'tcx> Visitor<'tcx> for PackedRefChecker<'_, 'tcx> { "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 \ + "packed structs are only aligned by one byte, and many modern architectures \ + penalize unaligned field accesses" + ) + .note( + "creating a misaligned reference is undefined behavior (even if that \ reference is never dereferenced)", ).help( "copy the field contents to a local variable, or replace the \ diff --git a/tests/ui/binding/issue-53114-safety-checks.stderr b/tests/ui/binding/issue-53114-safety-checks.stderr index 41318d0a38a..349c4639a9e 100644 --- a/tests/ui/binding/issue-53114-safety-checks.stderr +++ b/tests/ui/binding/issue-53114-safety-checks.stderr @@ -4,7 +4,8 @@ error[E0793]: reference to packed field is unaligned LL | let _ = &p.b; | ^^^^ | - = 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: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses + = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) error[E0793]: reference to packed field is unaligned @@ -13,7 +14,8 @@ error[E0793]: reference to packed field is unaligned LL | let (_,) = (&p.b,); | ^^^^ | - = 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: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses + = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) error[E0793]: reference to packed field is unaligned @@ -22,7 +24,8 @@ error[E0793]: reference to packed field is unaligned LL | let _: _ = &p.b; | ^^^^ | - = 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: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses + = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) error[E0793]: reference to packed field is unaligned @@ -31,7 +34,8 @@ error[E0793]: reference to packed field is unaligned LL | let (_,): _ = (&p.b,); | ^^^^ | - = 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: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses + = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) error[E0793]: reference to packed field is unaligned @@ -40,7 +44,8 @@ error[E0793]: reference to packed field is unaligned LL | match &p.b { _ => { } } | ^^^^ | - = 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: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses + = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) error[E0793]: reference to packed field is unaligned @@ -49,7 +54,8 @@ error[E0793]: reference to packed field is unaligned LL | match (&p.b,) { (_,) => { } } | ^^^^ | - = 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: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses + = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) error[E0133]: access to union field is unsafe and requires unsafe function or block diff --git a/tests/ui/closures/2229_closure_analysis/diagnostics/repr_packed.stderr b/tests/ui/closures/2229_closure_analysis/diagnostics/repr_packed.stderr index 9c2c434572a..8c44229bceb 100644 --- a/tests/ui/closures/2229_closure_analysis/diagnostics/repr_packed.stderr +++ b/tests/ui/closures/2229_closure_analysis/diagnostics/repr_packed.stderr @@ -4,7 +4,8 @@ error[E0793]: reference to packed field is unaligned LL | println!("{}", foo.x); | ^^^^^ | - = 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: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses + = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) = note: this error originates in the macro `$crate::format_args_nl` which comes from the expansion of the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info) diff --git a/tests/ui/lint/unaligned_references.stderr b/tests/ui/lint/unaligned_references.stderr index 775dcac678e..5f9cecadbff 100644 --- a/tests/ui/lint/unaligned_references.stderr +++ b/tests/ui/lint/unaligned_references.stderr @@ -4,7 +4,8 @@ error[E0793]: reference to packed field is unaligned LL | &self.x; | ^^^^^^^ | - = 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: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses + = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) error[E0793]: reference to packed field is unaligned @@ -13,7 +14,8 @@ error[E0793]: reference to packed field is unaligned LL | let _ = &good.ptr; | ^^^^^^^^^ | - = 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: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses + = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) error[E0793]: reference to packed field is unaligned @@ -22,7 +24,8 @@ error[E0793]: reference to packed field is unaligned 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) + = note: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses + = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) error[E0793]: reference to packed field is unaligned @@ -31,7 +34,8 @@ error[E0793]: reference to packed field is unaligned 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) + = note: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses + = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) error[E0793]: reference to packed field is unaligned @@ -40,7 +44,8 @@ error[E0793]: reference to packed field is unaligned 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) + = note: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses + = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) error[E0793]: reference to packed field is unaligned @@ -49,7 +54,8 @@ error[E0793]: reference to packed field is unaligned 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) + = note: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses + = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) error[E0793]: reference to packed field is unaligned @@ -58,7 +64,8 @@ error[E0793]: reference to packed field is unaligned LL | let _ = &good.data2[0]; | ^^^^^^^^^^^^^^ | - = 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: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses + = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) error[E0793]: reference to packed field is unaligned @@ -67,7 +74,8 @@ error[E0793]: reference to packed field is unaligned LL | let _ = &packed2.x; | ^^^^^^^^^^ | - = 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: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses + = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) error[E0793]: reference to packed field is unaligned @@ -76,7 +84,8 @@ error[E0793]: reference to packed field is unaligned LL | let _ref = &m1.1.a; | ^^^^^^^ | - = 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: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses + = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) error[E0793]: reference to packed field is unaligned @@ -85,7 +94,8 @@ error[E0793]: reference to packed field is unaligned LL | let _ref = &m2.1.a; | ^^^^^^^ | - = 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: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses + = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) error: aborting due to 10 previous errors diff --git a/tests/ui/lint/unaligned_references_external_macro.stderr b/tests/ui/lint/unaligned_references_external_macro.stderr index 5b08f433e32..94a95c1d8fd 100644 --- a/tests/ui/lint/unaligned_references_external_macro.stderr +++ b/tests/ui/lint/unaligned_references_external_macro.stderr @@ -9,7 +9,8 @@ LL | | } LL | | } | |_^ | - = 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: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses + = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) = note: this error originates in the macro `unaligned_references_external_crate::mac` (in Nightly builds, run with -Z macro-backtrace for more info) diff --git a/tests/ui/packed/issue-27060.stderr b/tests/ui/packed/issue-27060.stderr index b4753284f72..4dc31a28386 100644 --- a/tests/ui/packed/issue-27060.stderr +++ b/tests/ui/packed/issue-27060.stderr @@ -4,7 +4,8 @@ error[E0793]: reference to packed field is unaligned 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) + = note: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses + = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) error[E0793]: reference to packed field is unaligned @@ -13,7 +14,8 @@ error[E0793]: reference to packed field is unaligned LL | let _ = &good.data2[0]; | ^^^^^^^^^^^^^^ | - = 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: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses + = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) error[E0793]: reference to packed field is unaligned @@ -22,7 +24,8 @@ error[E0793]: reference to packed field is unaligned 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) + = note: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses + = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) error[E0793]: reference to packed field is unaligned @@ -31,7 +34,8 @@ error[E0793]: reference to packed field is unaligned LL | let _ = &good.data2[0]; | ^^^^^^^^^^^^^^ | - = 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: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses + = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) error: aborting due to 4 previous errors diff --git a/tests/ui/packed/packed-struct-borrow-element-64bit.stderr b/tests/ui/packed/packed-struct-borrow-element-64bit.stderr index 32943b0f07b..57630a4b470 100644 --- a/tests/ui/packed/packed-struct-borrow-element-64bit.stderr +++ b/tests/ui/packed/packed-struct-borrow-element-64bit.stderr @@ -4,7 +4,8 @@ error[E0793]: reference to packed field is unaligned LL | let brw = &foo.baz; | ^^^^^^^^ | - = 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: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses + = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) error: aborting due to previous error diff --git a/tests/ui/packed/packed-struct-borrow-element.stderr b/tests/ui/packed/packed-struct-borrow-element.stderr index 29d867fc5b9..c1f749d6fbb 100644 --- a/tests/ui/packed/packed-struct-borrow-element.stderr +++ b/tests/ui/packed/packed-struct-borrow-element.stderr @@ -4,7 +4,8 @@ error[E0793]: reference to packed field is unaligned LL | let brw = &foo.baz; | ^^^^^^^^ | - = 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: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses + = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) error[E0793]: reference to packed field is unaligned @@ -13,7 +14,8 @@ error[E0793]: reference to packed field is unaligned LL | let brw = &foo.baz; | ^^^^^^^^ | - = 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: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses + = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) error: aborting due to 2 previous errors