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| author | bors <bors@rust-lang.org> | 2024-05-29 11:57:13 +0000 |
|---|---|---|
| committer | bors <bors@rust-lang.org> | 2024-05-29 11:57:13 +0000 |
| commit | f2e1a3a80ae54734e1a3d306f31c2caebb05de9b (patch) | |
| tree | d2c0f2cc38fec93e1f792592bd48c2bd968c69da /src/tools/miri/tests | |
| parent | 4cf5723dbe471ef0a32857b968b91498551f5e38 (diff) | |
| parent | 37aeb75eb6c68dfee49e9ecdbd0c46e137b28bc7 (diff) | |
| download | rust-f2e1a3a80ae54734e1a3d306f31c2caebb05de9b.tar.gz rust-f2e1a3a80ae54734e1a3d306f31c2caebb05de9b.zip | |
Auto merge of #125360 - RalfJung:packed-field-reorder, r=fmease
don't inhibit random field reordering on repr(packed(1)) `inhibit_struct_field_reordering_opt` being false means we exclude this type from random field shuffling. However, `packed(1)` types can still be shuffled! The logic was added in https://github.com/rust-lang/rust/pull/48528 since it's pointless to reorder fields in packed(1) types (there's no padding that could be saved) -- but that shouldn't inhibit `-Zrandomize-layout` (which did not exist at the time). We could add an optimization elsewhere to not bother sorting the fields for `repr(packed)` types, but I don't think that's worth the effort. This *does* change the behavior in that we may now reorder fields of `packed(1)` structs (e.g. if there are niches, we'll try to move them to the start/end, according to `NicheBias`). We were always allowed to do that but so far we didn't. Quoting the [reference](https://doc.rust-lang.org/reference/type-layout.html): > On their own, align and packed do not provide guarantees about the order of fields in the layout of a struct or the layout of an enum variant, although they may be combined with representations (such as C) which do provide such guarantees.
Diffstat (limited to 'src/tools/miri/tests')
| -rw-r--r-- | src/tools/miri/tests/fail/reading_half_a_pointer.rs | 2 | ||||
| -rw-r--r-- | src/tools/miri/tests/fail/unaligned_pointers/field_requires_parent_struct_alignment2.rs | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/src/tools/miri/tests/fail/reading_half_a_pointer.rs b/src/tools/miri/tests/fail/reading_half_a_pointer.rs index 7dd98eab785..feac30b83c3 100644 --- a/src/tools/miri/tests/fail/reading_half_a_pointer.rs +++ b/src/tools/miri/tests/fail/reading_half_a_pointer.rs @@ -1,7 +1,7 @@ #![allow(dead_code)] // We use packed structs to get around alignment restrictions -#[repr(packed)] +#[repr(C, packed)] struct Data { pad: u8, ptr: &'static i32, diff --git a/src/tools/miri/tests/fail/unaligned_pointers/field_requires_parent_struct_alignment2.rs b/src/tools/miri/tests/fail/unaligned_pointers/field_requires_parent_struct_alignment2.rs index 8459c64ed2d..06dd97deeda 100644 --- a/src/tools/miri/tests/fail/unaligned_pointers/field_requires_parent_struct_alignment2.rs +++ b/src/tools/miri/tests/fail/unaligned_pointers/field_requires_parent_struct_alignment2.rs @@ -7,7 +7,7 @@ pub struct Aligned { _pad: [u8; 11], packed: Packed, } -#[repr(packed)] +#[repr(C, packed)] #[derive(Default, Copy, Clone)] pub struct Packed { _pad: [u8; 5], |