From a122dde217459c1decbce3452323807154763206 Mon Sep 17 00:00:00 2001 From: Jack Wrenn Date: Thu, 5 Dec 2024 20:15:08 +0000 Subject: [PATCH] do not implement unsafe auto traits for types with unsafe fields MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit If a type has unsafe fields, its safety invariants are not simply the conjunction of its field types' safety invariants. Consequently, it's invalid to reason about the safety properties of these types in a purely structural manner — i.e., the manner in which `auto` traits are implemented. Makes progress towards #132922. --- compiler/rustc_middle/src/ty/context.rs | 4 +++ compiler/rustc_middle/src/ty/sty.rs | 8 ++++++ .../src/solve/trait_goals.rs | 8 ++++++ .../src/traits/select/candidate_assembly.rs | 9 +++++++ compiler/rustc_type_ir/src/inherent.rs | 3 +++ compiler/rustc_type_ir/src/interner.rs | 3 +++ .../unsafe-fields/auto-traits.current.stderr | 17 ++++++++++++ .../ui/unsafe-fields/auto-traits.next.stderr | 17 ++++++++++++ tests/ui/unsafe-fields/auto-traits.rs | 26 +++++++++++++++++++ .../auxiliary/unsafe-fields-crate-dep.rs | 0 .../unsafe-fields-crate.rs | 0 .../unsafe-fields-crate.stderr | 0 .../unsafe-fields-parse.rs | 0 .../unsafe-fields-parse.stderr | 0 tests/ui/{ => unsafe-fields}/unsafe-fields.rs | 0 .../{ => unsafe-fields}/unsafe-fields.stderr | 0 16 files changed, 95 insertions(+) create mode 100644 tests/ui/unsafe-fields/auto-traits.current.stderr create mode 100644 tests/ui/unsafe-fields/auto-traits.next.stderr create mode 100644 tests/ui/unsafe-fields/auto-traits.rs rename tests/ui/{ => unsafe-fields}/auxiliary/unsafe-fields-crate-dep.rs (100%) rename tests/ui/{ => unsafe-fields}/unsafe-fields-crate.rs (100%) rename tests/ui/{ => unsafe-fields}/unsafe-fields-crate.stderr (100%) rename tests/ui/{ => unsafe-fields}/unsafe-fields-parse.rs (100%) rename tests/ui/{ => unsafe-fields}/unsafe-fields-parse.stderr (100%) rename tests/ui/{ => unsafe-fields}/unsafe-fields.rs (100%) rename tests/ui/{ => unsafe-fields}/unsafe-fields.stderr (100%) diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs index 3cbb2a3acf592..d4835bb07f689 100644 --- a/compiler/rustc_middle/src/ty/context.rs +++ b/compiler/rustc_middle/src/ty/context.rs @@ -585,6 +585,10 @@ impl<'tcx> Interner for TyCtxt<'tcx> { self.trait_def(trait_def_id).implement_via_object } + fn trait_is_unsafe(self, trait_def_id: Self::DefId) -> bool { + self.trait_def(trait_def_id).safety == hir::Safety::Unsafe + } + fn is_impl_trait_in_trait(self, def_id: DefId) -> bool { self.is_impl_trait_in_trait(def_id) } diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs index 142db8a17f04f..474062218c97a 100644 --- a/compiler/rustc_middle/src/ty/sty.rs +++ b/compiler/rustc_middle/src/ty/sty.rs @@ -978,6 +978,14 @@ impl<'tcx> rustc_type_ir::inherent::Ty> for Ty<'tcx> { fn async_destructor_ty(self, interner: TyCtxt<'tcx>) -> Ty<'tcx> { self.async_destructor_ty(interner) } + + fn has_unsafe_fields(self) -> bool { + if let ty::Adt(adt_def, ..) = self.kind() { + adt_def.all_fields().any(|x| x.safety == hir::Safety::Unsafe) + } else { + false + } + } } /// Type utilities diff --git a/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs b/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs index 6641d2bf92492..12df35d30b8f3 100644 --- a/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs +++ b/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs @@ -169,6 +169,14 @@ where return result; } + // Only consider auto impls of unsafe traits when there are no unsafe + // fields. + if ecx.cx().trait_is_unsafe(goal.predicate.def_id()) + && goal.predicate.self_ty().has_unsafe_fields() + { + return Err(NoSolution); + } + // We only look into opaque types during analysis for opaque types // outside of their defining scope. Doing so for opaques in the // defining scope may require calling `typeck` on the same item we're diff --git a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs index 32b4567aba4f0..3e2c8467d3220 100644 --- a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs +++ b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs @@ -18,6 +18,7 @@ use rustc_infer::traits::{ use rustc_middle::ty::fast_reject::DeepRejectCtxt; use rustc_middle::ty::{self, ToPolyTraitRef, Ty, TypeVisitableExt, TypingMode}; use rustc_middle::{bug, span_bug}; +use rustc_type_ir::Interner; use tracing::{debug, instrument, trace}; use super::SelectionCandidate::*; @@ -794,6 +795,14 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { | ty::Never | ty::Tuple(_) | ty::CoroutineWitness(..) => { + use rustc_type_ir::inherent::*; + + // Only consider auto impls of unsafe traits when there are + // no unsafe fields. + if self.tcx().trait_is_unsafe(def_id) && self_ty.has_unsafe_fields() { + return; + } + // Only consider auto impls if there are no manual impls for the root of `self_ty`. // // For example, we only consider auto candidates for `&i32: Auto` if no explicit impl diff --git a/compiler/rustc_type_ir/src/inherent.rs b/compiler/rustc_type_ir/src/inherent.rs index a201f2b1c11f1..f45c94127bd00 100644 --- a/compiler/rustc_type_ir/src/inherent.rs +++ b/compiler/rustc_type_ir/src/inherent.rs @@ -136,6 +136,9 @@ pub trait Ty>: matches!(self.kind(), ty::FnPtr(..)) } + /// Checks whether this type is an ADT that has unsafe fields. + fn has_unsafe_fields(self) -> bool; + fn fn_sig(self, interner: I) -> ty::Binder> { match self.kind() { ty::FnPtr(sig_tys, hdr) => sig_tys.with(hdr), diff --git a/compiler/rustc_type_ir/src/interner.rs b/compiler/rustc_type_ir/src/interner.rs index 0ae688848ebfc..025ec7ae896dd 100644 --- a/compiler/rustc_type_ir/src/interner.rs +++ b/compiler/rustc_type_ir/src/interner.rs @@ -270,6 +270,9 @@ pub trait Interner: fn trait_may_be_implemented_via_object(self, trait_def_id: Self::DefId) -> bool; + /// Returns `true` if this is an `unsafe trait`. + fn trait_is_unsafe(self, trait_def_id: Self::DefId) -> bool; + fn is_impl_trait_in_trait(self, def_id: Self::DefId) -> bool; fn delay_bug(self, msg: impl ToString) -> Self::ErrorGuaranteed; diff --git a/tests/ui/unsafe-fields/auto-traits.current.stderr b/tests/ui/unsafe-fields/auto-traits.current.stderr new file mode 100644 index 0000000000000..53a97458b7cd7 --- /dev/null +++ b/tests/ui/unsafe-fields/auto-traits.current.stderr @@ -0,0 +1,17 @@ +error[E0277]: the trait bound `UnsafeEnum: UnsafeAuto` is not satisfied + --> $DIR/auto-traits.rs:24:22 + | +LL | impl_unsafe_auto(UnsafeEnum::Safe(42)); + | ---------------- ^^^^^^^^^^^^^^^^^^^^ the trait `UnsafeAuto` is not implemented for `UnsafeEnum` + | | + | required by a bound introduced by this call + | +note: required by a bound in `impl_unsafe_auto` + --> $DIR/auto-traits.rs:20:29 + | +LL | fn impl_unsafe_auto(_: impl UnsafeAuto) {} + | ^^^^^^^^^^ required by this bound in `impl_unsafe_auto` + +error: aborting due to 1 previous error + +For more information about this error, try `rustc --explain E0277`. diff --git a/tests/ui/unsafe-fields/auto-traits.next.stderr b/tests/ui/unsafe-fields/auto-traits.next.stderr new file mode 100644 index 0000000000000..53a97458b7cd7 --- /dev/null +++ b/tests/ui/unsafe-fields/auto-traits.next.stderr @@ -0,0 +1,17 @@ +error[E0277]: the trait bound `UnsafeEnum: UnsafeAuto` is not satisfied + --> $DIR/auto-traits.rs:24:22 + | +LL | impl_unsafe_auto(UnsafeEnum::Safe(42)); + | ---------------- ^^^^^^^^^^^^^^^^^^^^ the trait `UnsafeAuto` is not implemented for `UnsafeEnum` + | | + | required by a bound introduced by this call + | +note: required by a bound in `impl_unsafe_auto` + --> $DIR/auto-traits.rs:20:29 + | +LL | fn impl_unsafe_auto(_: impl UnsafeAuto) {} + | ^^^^^^^^^^ required by this bound in `impl_unsafe_auto` + +error: aborting due to 1 previous error + +For more information about this error, try `rustc --explain E0277`. diff --git a/tests/ui/unsafe-fields/auto-traits.rs b/tests/ui/unsafe-fields/auto-traits.rs new file mode 100644 index 0000000000000..e15d0000079ef --- /dev/null +++ b/tests/ui/unsafe-fields/auto-traits.rs @@ -0,0 +1,26 @@ +//@ compile-flags: --crate-type=lib +//@ revisions: current next +//@[next] compile-flags: -Znext-solver + +#![feature(auto_traits)] +#![feature(unsafe_fields)] +#![allow(incomplete_features)] + +enum UnsafeEnum { + Safe(u8), + Unsafe { unsafe field: u8 }, +} + +auto trait SafeAuto {} + +fn impl_safe_auto(_: impl SafeAuto) {} + +unsafe auto trait UnsafeAuto {} + +fn impl_unsafe_auto(_: impl UnsafeAuto) {} + +fn tests() { + impl_safe_auto(UnsafeEnum::Safe(42)); + impl_unsafe_auto(UnsafeEnum::Safe(42)); + //~^ ERROR the trait bound `UnsafeEnum: UnsafeAuto` is not satisfied +} diff --git a/tests/ui/auxiliary/unsafe-fields-crate-dep.rs b/tests/ui/unsafe-fields/auxiliary/unsafe-fields-crate-dep.rs similarity index 100% rename from tests/ui/auxiliary/unsafe-fields-crate-dep.rs rename to tests/ui/unsafe-fields/auxiliary/unsafe-fields-crate-dep.rs diff --git a/tests/ui/unsafe-fields-crate.rs b/tests/ui/unsafe-fields/unsafe-fields-crate.rs similarity index 100% rename from tests/ui/unsafe-fields-crate.rs rename to tests/ui/unsafe-fields/unsafe-fields-crate.rs diff --git a/tests/ui/unsafe-fields-crate.stderr b/tests/ui/unsafe-fields/unsafe-fields-crate.stderr similarity index 100% rename from tests/ui/unsafe-fields-crate.stderr rename to tests/ui/unsafe-fields/unsafe-fields-crate.stderr diff --git a/tests/ui/unsafe-fields-parse.rs b/tests/ui/unsafe-fields/unsafe-fields-parse.rs similarity index 100% rename from tests/ui/unsafe-fields-parse.rs rename to tests/ui/unsafe-fields/unsafe-fields-parse.rs diff --git a/tests/ui/unsafe-fields-parse.stderr b/tests/ui/unsafe-fields/unsafe-fields-parse.stderr similarity index 100% rename from tests/ui/unsafe-fields-parse.stderr rename to tests/ui/unsafe-fields/unsafe-fields-parse.stderr diff --git a/tests/ui/unsafe-fields.rs b/tests/ui/unsafe-fields/unsafe-fields.rs similarity index 100% rename from tests/ui/unsafe-fields.rs rename to tests/ui/unsafe-fields/unsafe-fields.rs diff --git a/tests/ui/unsafe-fields.stderr b/tests/ui/unsafe-fields/unsafe-fields.stderr similarity index 100% rename from tests/ui/unsafe-fields.stderr rename to tests/ui/unsafe-fields/unsafe-fields.stderr