diff --git a/src/librustc_mir/interpret/eval_context.rs b/src/librustc_mir/interpret/eval_context.rs index 9bb7c879505f..eba4dd336ade 100644 --- a/src/librustc_mir/interpret/eval_context.rs +++ b/src/librustc_mir/interpret/eval_context.rs @@ -871,6 +871,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { // Our result will later be validated anyway, and there seems no good reason // to have to fail early here. This is also more consistent with // `Memory::get_static_alloc` which has to use `const_eval_raw` to avoid cycles. + // FIXME: We can hit delay_span_bug if this is an invalid const, interning finds + // that problem, but we never run validation to show an error. Can we ensure + // this does not happen? let val = self.tcx.const_eval_raw(param_env.and(gid))?; self.raw_const_to_mplace(val) } diff --git a/src/librustc_mir/interpret/intern.rs b/src/librustc_mir/interpret/intern.rs index 1c44101595d4..c9661c92d2e2 100644 --- a/src/librustc_mir/interpret/intern.rs +++ b/src/librustc_mir/interpret/intern.rs @@ -8,7 +8,7 @@ use rustc_data_structures::fx::{FxHashMap, FxHashSet}; use rustc_errors::ErrorReported; use rustc_hir as hir; use rustc_middle::mir::interpret::{ErrorHandled, InterpResult}; -use rustc_middle::ty::{self, Ty}; +use rustc_middle::ty::{self, query::TyCtxtAt, Ty}; use rustc_ast::ast::Mutability; @@ -29,43 +29,44 @@ struct InternVisitor<'rt, 'mir, 'tcx, M: CompileTimeMachine<'mir, 'tcx>> { /// The ectx from which we intern. ecx: &'rt mut InterpCx<'mir, 'tcx, M>, /// Previously encountered safe references. - ref_tracking: &'rt mut RefTracking<(MPlaceTy<'tcx>, Mutability, InternMode)>, + ref_tracking: &'rt mut RefTracking<(MPlaceTy<'tcx>, InternMode)>, /// A list of all encountered allocations. After type-based interning, we traverse this list to /// also intern allocations that are only referenced by a raw pointer or inside a union. leftover_allocations: &'rt mut FxHashSet, - /// The root node of the value that we're looking at. This field is never mutated and only used + /// The root kind of the value that we're looking at. This field is never mutated and only used /// for sanity assertions that will ICE when `const_qualif` screws up. mode: InternMode, - /// This field stores the mutability of the value *currently* being checked. - /// When encountering a mutable reference, we determine the pointee mutability - /// taking into account the mutability of the context: `& &mut i32` is entirely immutable, - /// despite the nested mutable reference! - /// The field gets updated when an `UnsafeCell` is encountered. - mutability: Mutability, + /// This field stores whether we are *currently* inside an `UnsafeCell`. This can affect + /// the intern mode of references we encounter. + inside_unsafe_cell: bool, /// This flag is to avoid triggering UnsafeCells are not allowed behind references in constants /// for promoteds. /// It's a copy of `mir::Body`'s ignore_interior_mut_in_const_validation field - ignore_interior_mut_in_const_validation: bool, + ignore_interior_mut_in_const: bool, } #[derive(Copy, Clone, Debug, PartialEq, Hash, Eq)] enum InternMode { - /// Mutable references must in fact be immutable due to their surrounding immutability in a - /// `static`. In a `static mut` we start out as mutable and thus can also contain further `&mut` - /// that will actually be treated as mutable. - Static, - /// UnsafeCell is OK in the value of a constant: `const FOO = Cell::new(0)` creates - /// a new cell every time it is used. + /// A static and its current mutability. Below shared references inside a `static mut`, + /// this is *immutable*, and below mutable references inside an `UnsafeCell`, this + /// is *mutable*. + Static(hir::Mutability), + /// The "base value" of a const, which can have `UnsafeCell` (as in `const FOO: Cell`), + /// but that interior mutability is simply ignored. ConstBase, - /// `UnsafeCell` ICEs. - Const, + /// The "inner values" of a const with references, where `UnsafeCell` is an error. + ConstInner, } /// Signalling data structure to ensure we don't recurse /// into the memory of other constants or statics struct IsStaticOrFn; +fn mutable_memory_in_const(tcx: TyCtxtAt<'_>, kind: &str) { + tcx.sess.span_err(tcx.span, &format!("mutable memory ({}) is not allowed in constant", kind)); +} + /// Intern an allocation without looking at its children. /// `mode` is the mode of the environment where we found this pointer. /// `mutablity` is the mutability of the place to be interned; even if that says @@ -75,12 +76,11 @@ struct IsStaticOrFn; fn intern_shallow<'rt, 'mir, 'tcx, M: CompileTimeMachine<'mir, 'tcx>>( ecx: &'rt mut InterpCx<'mir, 'tcx, M>, leftover_allocations: &'rt mut FxHashSet, - mode: InternMode, alloc_id: AllocId, - mutability: Mutability, + mode: InternMode, ty: Option>, ) -> InterpResult<'tcx, Option> { - trace!("InternVisitor::intern {:?} with {:?}", alloc_id, mutability,); + trace!("intern_shallow {:?} with {:?}", alloc_id, mode); // remove allocation let tcx = ecx.tcx; let (kind, mut alloc) = match ecx.memory.alloc_map.remove(&alloc_id) { @@ -89,8 +89,9 @@ fn intern_shallow<'rt, 'mir, 'tcx, M: CompileTimeMachine<'mir, 'tcx>>( // Pointer not found in local memory map. It is either a pointer to the global // map, or dangling. // If the pointer is dangling (neither in local nor global memory), we leave it - // to validation to error. The `delay_span_bug` ensures that we don't forget such - // a check in validation. + // to validation to error -- it has the much better error messages, pointing out where + // in the value the dangling reference lies. + // The `delay_span_bug` ensures that we don't forget such a check in validation. if tcx.get_global_alloc(alloc_id).is_none() { tcx.sess.delay_span_bug(ecx.tcx.span, "tried to intern dangling pointer"); } @@ -107,28 +108,28 @@ fn intern_shallow<'rt, 'mir, 'tcx, M: CompileTimeMachine<'mir, 'tcx>>( // Set allocation mutability as appropriate. This is used by LLVM to put things into // read-only memory, and also by Miri when evaluating other globals that // access this one. - if mode == InternMode::Static { - // When `ty` is `None`, we assume no interior mutability. + if let InternMode::Static(mutability) = mode { + // For this, we need to take into account `UnsafeCell`. When `ty` is `None`, we assume + // no interior mutability. let frozen = ty.map_or(true, |ty| ty.is_freeze(ecx.tcx.tcx, ecx.param_env, ecx.tcx.span)); // For statics, allocation mutability is the combination of the place mutability and // the type mutability. // The entire allocation needs to be mutable if it contains an `UnsafeCell` anywhere. - if mutability == Mutability::Not && frozen { + let immutable = mutability == Mutability::Not && frozen; + if immutable { alloc.mutability = Mutability::Not; } else { // Just making sure we are not "upgrading" an immutable allocation to mutable. assert_eq!(alloc.mutability, Mutability::Mut); } } else { - // We *could* be non-frozen at `ConstBase`, for constants like `Cell::new(0)`. - // But we still intern that as immutable as the memory cannot be changed once the - // initial value was computed. - // Constants are never mutable. - assert_eq!( - mutability, - Mutability::Not, - "Something went very wrong: mutability requested for a constant" - ); + // No matter what, *constants are never mutable*. Mutating them is UB. + // See const_eval::machine::MemoryExtra::can_access_statics for why + // immutability is so important. + + // There are no sensible checks we can do here; grep for `mutable_memory_in_const` to + // find the checks we are doing elsewhere to avoid even getting here for memory + // that "wants" to be mutable. alloc.mutability = Mutability::Not; }; // link the alloc id to the actual allocation @@ -142,10 +143,16 @@ impl<'rt, 'mir, 'tcx, M: CompileTimeMachine<'mir, 'tcx>> InternVisitor<'rt, 'mir fn intern_shallow( &mut self, alloc_id: AllocId, - mutability: Mutability, + mode: InternMode, ty: Option>, ) -> InterpResult<'tcx, Option> { - intern_shallow(self.ecx, self.leftover_allocations, self.mode, alloc_id, mutability, ty) + intern_shallow( + self.ecx, + self.leftover_allocations, + alloc_id, + mode, + ty, + ) } } @@ -166,22 +173,22 @@ impl<'rt, 'mir, 'tcx: 'mir, M: CompileTimeMachine<'mir, 'tcx>> ValueVisitor<'mir ) -> InterpResult<'tcx> { if let Some(def) = mplace.layout.ty.ty_adt_def() { if Some(def.did) == self.ecx.tcx.lang_items().unsafe_cell_type() { + if self.mode == InternMode::ConstInner && !self.ignore_interior_mut_in_const { + // We do not actually make this memory mutable. But in case the user + // *expected* it to be mutable, make sure we error. This is just a + // sanity check to prevent users from accidentally exploiting the UB + // they caused. It also helps us to find cases where const-checking + // failed to prevent an `UnsafeCell` (but as `ignore_interior_mut_in_const` + // shows that part is not airtight). + mutable_memory_in_const(self.ecx.tcx, "`UnsafeCell`"); + } // We are crossing over an `UnsafeCell`, we can mutate again. This means that // References we encounter inside here are interned as pointing to mutable // allocations. - let old = std::mem::replace(&mut self.mutability, Mutability::Mut); - if !self.ignore_interior_mut_in_const_validation { - assert_ne!( - self.mode, - InternMode::Const, - "UnsafeCells are not allowed behind references in constants. This should \ - have been prevented statically by const qualification. If this were \ - allowed one would be able to change a constant at one use site and other \ - use sites could observe that mutation.", - ); - } + // Remember the `old` value to handle nested `UnsafeCell`. + let old = std::mem::replace(&mut self.inside_unsafe_cell, true); let walked = self.walk_aggregate(mplace, fields); - self.mutability = old; + self.inside_unsafe_cell = old; return walked; } } @@ -191,23 +198,26 @@ impl<'rt, 'mir, 'tcx: 'mir, M: CompileTimeMachine<'mir, 'tcx>> ValueVisitor<'mir fn visit_value(&mut self, mplace: MPlaceTy<'tcx>) -> InterpResult<'tcx> { // Handle Reference types, as these are the only relocations supported by const eval. // Raw pointers (and boxes) are handled by the `leftover_relocations` logic. + let tcx = self.ecx.tcx; let ty = mplace.layout.ty; - if let ty::Ref(_, referenced_ty, mutability) = ty.kind { + if let ty::Ref(_, referenced_ty, ref_mutability) = ty.kind { let value = self.ecx.read_immediate(mplace.into())?; let mplace = self.ecx.ref_to_mplace(value)?; + assert_eq!(mplace.layout.ty, referenced_ty); // Handle trait object vtables. if let ty::Dynamic(..) = - self.ecx.tcx.struct_tail_erasing_lifetimes(referenced_ty, self.ecx.param_env).kind + tcx.struct_tail_erasing_lifetimes(referenced_ty, self.ecx.param_env).kind { - // Validation has already errored on an invalid vtable pointer so we can safely not - // do anything if this is not a real pointer. + // Validation will error (with a better message) on an invalid vtable pointer + // so we can safely not do anything if this is not a real pointer. if let Scalar::Ptr(vtable) = mplace.meta.unwrap_meta() { - // Explicitly choose `Immutable` here, since vtables are immutable, even + // Explicitly choose const mode here, since vtables are immutable, even // if the reference of the fat pointer is mutable. - self.intern_shallow(vtable.alloc_id, Mutability::Not, None)?; + self.intern_shallow(vtable.alloc_id, InternMode::ConstInner, None)?; } else { - self.ecx().tcx.sess.delay_span_bug( - rustc_span::DUMMY_SP, + // Let validation show the error message, but make sure it *does* error. + tcx.sess.delay_span_bug( + tcx.span, "vtables pointers cannot be integer pointers", ); } @@ -215,54 +225,66 @@ impl<'rt, 'mir, 'tcx: 'mir, M: CompileTimeMachine<'mir, 'tcx>> ValueVisitor<'mir // Check if we have encountered this pointer+layout combination before. // Only recurse for allocation-backed pointers. if let Scalar::Ptr(ptr) = mplace.ptr { - // We do not have any `frozen` logic here, because it's essentially equivalent to - // the mutability except for the outermost item. Only `UnsafeCell` can "unfreeze", - // and we check that in `visit_aggregate`. - // This is not an inherent limitation, but one that we know to be true, because - // const qualification enforces it. We can lift it in the future. - match (self.mode, mutability) { - // immutable references are fine everywhere - (_, hir::Mutability::Not) => {} - // all is "good and well" in the unsoundness of `static mut` + // Compute the mode with which we intern this. + let ref_mode = match self.mode { + InternMode::Static(mutbl) => { + // In statics, merge outer mutability with reference mutability and + // take into account whether we are in an `UnsafeCell`. - // mutable references are ok in `static`. Either they are treated as immutable - // because they are behind an immutable one, or they are behind an `UnsafeCell` - // and thus ok. - (InternMode::Static, hir::Mutability::Mut) => {} - // we statically prevent `&mut T` via `const_qualif` and double check this here - (InternMode::ConstBase | InternMode::Const, hir::Mutability::Mut) => { - match referenced_ty.kind { - ty::Array(_, n) - if n.eval_usize(self.ecx.tcx.tcx, self.ecx.param_env) == 0 => {} - ty::Slice(_) - if mplace.meta.unwrap_meta().to_machine_usize(self.ecx)? == 0 => {} - _ => bug!("const qualif failed to prevent mutable references"), + // The only way a mutable reference actually works as a mutable reference is + // by being in a `static mut` directly or behind another mutable reference. + // If there's an immutable reference or we are inside a `static`, then our + // mutable reference is equivalent to an immutable one. As an example: + // `&&mut Foo` is semantically equivalent to `&&Foo` + match ref_mutability { + _ if self.inside_unsafe_cell => { + // Inside an `UnsafeCell` is like inside a `static mut`, the "outer" + // mutability does not matter. + InternMode::Static(ref_mutability) + } + Mutability::Not => { + // A shared reference, things become immutable. + // We do *not* consier `freeze` here -- that is done more precisely + // when traversing the referenced data (by tracking `UnsafeCell`). + InternMode::Static(Mutability::Not) + } + Mutability::Mut => { + // Mutable reference. + InternMode::Static(mutbl) + } } } - } - // Compute the mutability with which we'll start visiting the allocation. This is - // what gets changed when we encounter an `UnsafeCell`. - // - // The only way a mutable reference actually works as a mutable reference is - // by being in a `static mut` directly or behind another mutable reference. - // If there's an immutable reference or we are inside a static, then our - // mutable reference is equivalent to an immutable one. As an example: - // `&&mut Foo` is semantically equivalent to `&&Foo` - let mutability = self.mutability.and(mutability); - // Recursing behind references changes the intern mode for constants in order to - // cause assertions to trigger if we encounter any `UnsafeCell`s. - let mode = match self.mode { - InternMode::ConstBase => InternMode::Const, - other => other, + InternMode::ConstBase | InternMode::ConstInner => { + // Ignore `UnsafeCell`, everything is immutable. Do some sanity checking + // for mutable references that we encounter -- they must all be ZST. + // This helps to prevent users from accidentally exploiting UB that they + // caused (by somehow getting a mutable reference in a `const`). + if ref_mutability == Mutability::Mut { + match referenced_ty.kind { + ty::Array(_, n) + if n.eval_usize(tcx.tcx, self.ecx.param_env) == 0 => {} + ty::Slice(_) + if mplace.meta.unwrap_meta().to_machine_usize(self.ecx)? == 0 => {} + _ => mutable_memory_in_const(tcx, "`&mut`"), + } + } else { + // A shared reference. We cannot check `freeze` here due to references + // like `&dyn Trait` that are actually immutable. We do check for + // concrete `UnsafeCell` when traversing the pointee though (if it is + // a new allocation, not yet interned). + } + // Go on with the "inner" rules. + InternMode::ConstInner + } }; - match self.intern_shallow(ptr.alloc_id, mutability, Some(mplace.layout.ty))? { + match self.intern_shallow(ptr.alloc_id, ref_mode, Some(referenced_ty))? { // No need to recurse, these are interned already and statics may have // cycles, so we don't want to recurse there Some(IsStaticOrFn) => {} // intern everything referenced by this value. The mutability is taken from the // reference. It is checked above that mutable references only happen in // `static mut` - None => self.ref_tracking.track((mplace, mutability, mode), || ()), + None => self.ref_tracking.track((mplace, ref_mode), || ()), } } Ok(()) @@ -273,6 +295,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: CompileTimeMachine<'mir, 'tcx>> ValueVisitor<'mir } } +#[derive(Copy, Clone, Debug, PartialEq, Hash, Eq)] pub enum InternKind { /// The `mutability` of the static, ignoring the type which may have interior mutability. Static(hir::Mutability), @@ -285,48 +308,48 @@ pub fn intern_const_alloc_recursive>( ecx: &mut InterpCx<'mir, 'tcx, M>, intern_kind: InternKind, ret: MPlaceTy<'tcx>, - ignore_interior_mut_in_const_validation: bool, + ignore_interior_mut_in_const: bool, ) -> InterpResult<'tcx> where 'tcx: 'mir, { let tcx = ecx.tcx; - let (base_mutability, base_intern_mode) = match intern_kind { - // `static mut` doesn't care about interior mutability, it's mutable anyway - InternKind::Static(mutbl) => (mutbl, InternMode::Static), + let base_intern_mode = match intern_kind { + InternKind::Static(mutbl) => InternMode::Static(mutbl), // FIXME: what about array lengths, array initializers? - InternKind::Constant | InternKind::ConstProp => (Mutability::Not, InternMode::ConstBase), - InternKind::Promoted => (Mutability::Not, InternMode::ConstBase), + InternKind::Constant | InternKind::ConstProp | InternKind::Promoted => + InternMode::ConstBase, }; // Type based interning. - // `ref_tracking` tracks typed references we have seen and still need to crawl for + // `ref_tracking` tracks typed references we have already interned and still need to crawl for // more typed information inside them. // `leftover_allocations` collects *all* allocations we see, because some might not // be available in a typed way. They get interned at the end. - let mut ref_tracking = RefTracking::new((ret, base_mutability, base_intern_mode)); + let mut ref_tracking = RefTracking::empty(); let leftover_allocations = &mut FxHashSet::default(); // start with the outermost allocation intern_shallow( ecx, leftover_allocations, - base_intern_mode, // The outermost allocation must exist, because we allocated it with // `Memory::allocate`. ret.ptr.assert_ptr().alloc_id, - base_mutability, + base_intern_mode, Some(ret.layout.ty), )?; - while let Some(((mplace, mutability, mode), _)) = ref_tracking.todo.pop() { + ref_tracking.track((ret, base_intern_mode), || ()); + + while let Some(((mplace, mode), _)) = ref_tracking.todo.pop() { let interned = InternVisitor { ref_tracking: &mut ref_tracking, ecx, mode, leftover_allocations, - mutability, - ignore_interior_mut_in_const_validation, + ignore_interior_mut_in_const, + inside_unsafe_cell: false, } .visit_value(mplace); if let Err(error) = interned { @@ -366,26 +389,28 @@ where InternKind::Static(_) => {} // Raw pointers in promoteds may only point to immutable things so we mark // everything as immutable. - // It is UB to mutate through a raw pointer obtained via an immutable reference. + // It is UB to mutate through a raw pointer obtained via an immutable reference: // Since all references and pointers inside a promoted must by their very definition // be created from an immutable reference (and promotion also excludes interior // mutability), mutating through them would be UB. // There's no way we can check whether the user is using raw pointers correctly, // so all we can do is mark this as immutable here. InternKind::Promoted => { + // See const_eval::machine::MemoryExtra::can_access_statics for why + // immutability is so important. alloc.mutability = Mutability::Not; } InternKind::Constant | InternKind::ConstProp => { - // If it's a constant, it *must* be immutable. - // We cannot have mutable memory inside a constant. - // We use `delay_span_bug` here, because this can be reached in the presence - // of fancy transmutes. - if alloc.mutability == Mutability::Mut { - // For better errors later, mark the allocation as immutable - // (on top of the delayed ICE). - alloc.mutability = Mutability::Not; - ecx.tcx.sess.delay_span_bug(ecx.tcx.span, "mutable allocation in constant"); - } + // If it's a constant, we should not have any "leftovers" as everything + // is tracked by const-checking. + // FIXME: downgrade this to a warning? It rejects some legitimate consts, + // such as `const CONST_RAW: *const Vec = &Vec::new() as *const _;`. + ecx.tcx.sess.span_err( + ecx.tcx.span, + "untyped pointers are not allowed in constant", + ); + // For better errors later, mark the allocation as immutable. + alloc.mutability = Mutability::Not; } } let alloc = tcx.intern_const_alloc(alloc); diff --git a/src/test/ui/consts/miri_unleashed/mutable_const.rs b/src/test/ui/consts/miri_unleashed/mutable_const.rs deleted file mode 100644 index f8aa65282738..000000000000 --- a/src/test/ui/consts/miri_unleashed/mutable_const.rs +++ /dev/null @@ -1,25 +0,0 @@ -// compile-flags: -Zunleash-the-miri-inside-of-you -// normalize-stderr-test "alloc[0-9]+" -> "allocN" - -#![deny(const_err)] // The `allow` variant is tested by `mutable_const2`. -//~^ NOTE lint level -// Here we check that even though `MUTABLE_BEHIND_RAW` is created from a mutable -// allocation, we intern that allocation as *immutable* and reject writes to it. -// We avoid the `delay_span_bug` ICE by having compilation fail via the `deny` above. - -use std::cell::UnsafeCell; - -// make sure we do not just intern this as mutable -const MUTABLE_BEHIND_RAW: *mut i32 = &UnsafeCell::new(42) as *const _ as *mut _; - -const MUTATING_BEHIND_RAW: () = { //~ NOTE - // Test that `MUTABLE_BEHIND_RAW` is actually immutable, by doing this at const time. - unsafe { - *MUTABLE_BEHIND_RAW = 99 //~ ERROR any use of this value will cause an error - //~^ NOTE: which is read-only - // FIXME would be good to match more of the error message here, but looks like we - // normalize *after* checking the annoations here. - } -}; - -fn main() {} diff --git a/src/test/ui/consts/miri_unleashed/mutable_const.stderr b/src/test/ui/consts/miri_unleashed/mutable_const.stderr deleted file mode 100644 index 4772baf9d9a0..000000000000 --- a/src/test/ui/consts/miri_unleashed/mutable_const.stderr +++ /dev/null @@ -1,39 +0,0 @@ -error: any use of this value will cause an error - --> $DIR/mutable_const.rs:18:9 - | -LL | / const MUTATING_BEHIND_RAW: () = { -LL | | // Test that `MUTABLE_BEHIND_RAW` is actually immutable, by doing this at const time. -LL | | unsafe { -LL | | *MUTABLE_BEHIND_RAW = 99 - | | ^^^^^^^^^^^^^^^^^^^^^^^^ writing to allocN which is read-only -... | -LL | | } -LL | | }; - | |__- - | -note: the lint level is defined here - --> $DIR/mutable_const.rs:4:9 - | -LL | #![deny(const_err)] // The `allow` variant is tested by `mutable_const2`. - | ^^^^^^^^^ - -warning: skipping const checks - | -help: skipping check that does not even have a feature gate - --> $DIR/mutable_const.rs:13:38 - | -LL | const MUTABLE_BEHIND_RAW: *mut i32 = &UnsafeCell::new(42) as *const _ as *mut _; - | ^^^^^^^^^^^^^^^^^^^^ -help: skipping check for `const_raw_ptr_deref` feature - --> $DIR/mutable_const.rs:18:9 - | -LL | *MUTABLE_BEHIND_RAW = 99 - | ^^^^^^^^^^^^^^^^^^^^^^^^ -help: skipping check for `const_mut_refs` feature - --> $DIR/mutable_const.rs:18:9 - | -LL | *MUTABLE_BEHIND_RAW = 99 - | ^^^^^^^^^^^^^^^^^^^^^^^^ - -error: aborting due to previous error; 1 warning emitted - diff --git a/src/test/ui/consts/miri_unleashed/mutable_const2.rs b/src/test/ui/consts/miri_unleashed/mutable_const2.rs deleted file mode 100644 index 867091af7ba7..000000000000 --- a/src/test/ui/consts/miri_unleashed/mutable_const2.rs +++ /dev/null @@ -1,16 +0,0 @@ -// compile-flags: -Zunleash-the-miri-inside-of-you -// failure-status: 101 -// rustc-env:RUST_BACKTRACE=0 -// normalize-stderr-test "note: rustc 1.* running on .*" -> "note: rustc VERSION running on TARGET" -// normalize-stderr-test "note: compiler flags: .*" -> "note: compiler flags: FLAGS" -// normalize-stderr-test "interpret/intern.rs:[0-9]+:[0-9]+" -> "interpret/intern.rs:LL:CC" - -#![allow(const_err)] - -use std::cell::UnsafeCell; - -// make sure we do not just intern this as mutable -const MUTABLE_BEHIND_RAW: *mut i32 = &UnsafeCell::new(42) as *const _ as *mut _; -//~^ ERROR: mutable allocation in constant - -fn main() {} diff --git a/src/test/ui/consts/miri_unleashed/mutable_const2.stderr b/src/test/ui/consts/miri_unleashed/mutable_const2.stderr deleted file mode 100644 index 98a1c8bdd896..000000000000 --- a/src/test/ui/consts/miri_unleashed/mutable_const2.stderr +++ /dev/null @@ -1,29 +0,0 @@ -warning: skipping const checks - | -help: skipping check that does not even have a feature gate - --> $DIR/mutable_const2.rs:13:38 - | -LL | const MUTABLE_BEHIND_RAW: *mut i32 = &UnsafeCell::new(42) as *const _ as *mut _; - | ^^^^^^^^^^^^^^^^^^^^ - -warning: 1 warning emitted - -error: internal compiler error: mutable allocation in constant - --> $DIR/mutable_const2.rs:13:1 - | -LL | const MUTABLE_BEHIND_RAW: *mut i32 = &UnsafeCell::new(42) as *const _ as *mut _; - | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ - -thread 'rustc' panicked at 'no errors encountered even though `delay_span_bug` issued', src/librustc_errors/lib.rs:366:17 -note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace - -error: internal compiler error: unexpected panic - -note: the compiler unexpectedly panicked. this is a bug. - -note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports - -note: rustc VERSION running on TARGET - -note: compiler flags: FLAGS - diff --git a/src/test/ui/consts/miri_unleashed/mutable_references.rs b/src/test/ui/consts/miri_unleashed/mutable_references.rs index ed2ca86ba2c6..ca927ef4a518 100644 --- a/src/test/ui/consts/miri_unleashed/mutable_references.rs +++ b/src/test/ui/consts/miri_unleashed/mutable_references.rs @@ -17,12 +17,11 @@ struct Foo(T); // this is fine for the same reason as `BAR`. static BOO: &mut Foo<()> = &mut Foo(()); +// interior mutability is fine struct Meh { x: &'static UnsafeCell, } - unsafe impl Sync for Meh {} - static MEH: Meh = Meh { x: &UnsafeCell::new(42), }; diff --git a/src/test/ui/consts/miri_unleashed/mutable_references.stderr b/src/test/ui/consts/miri_unleashed/mutable_references.stderr index 83c4e0ceba0d..7109ffd8b61d 100644 --- a/src/test/ui/consts/miri_unleashed/mutable_references.stderr +++ b/src/test/ui/consts/miri_unleashed/mutable_references.stderr @@ -1,5 +1,5 @@ error[E0594]: cannot assign to `*OH_YES`, as `OH_YES` is an immutable static item - --> $DIR/mutable_references.rs:37:5 + --> $DIR/mutable_references.rs:36:5 | LL | *OH_YES = 99; | ^^^^^^^^^^^^ cannot assign @@ -22,12 +22,12 @@ help: skipping check for `const_mut_refs` feature LL | static BOO: &mut Foo<()> = &mut Foo(()); | ^^^^^^^^^^^^ help: skipping check that does not even have a feature gate - --> $DIR/mutable_references.rs:27:8 + --> $DIR/mutable_references.rs:26:8 | LL | x: &UnsafeCell::new(42), | ^^^^^^^^^^^^^^^^^^^^ help: skipping check for `const_mut_refs` feature - --> $DIR/mutable_references.rs:31:27 + --> $DIR/mutable_references.rs:30:27 | LL | static OH_YES: &mut i32 = &mut 42; | ^^^^^^^ diff --git a/src/test/ui/consts/miri_unleashed/mutable_references_err.rs b/src/test/ui/consts/miri_unleashed/mutable_references_err.rs new file mode 100644 index 000000000000..5014a601390d --- /dev/null +++ b/src/test/ui/consts/miri_unleashed/mutable_references_err.rs @@ -0,0 +1,37 @@ +// compile-flags: -Zunleash-the-miri-inside-of-you + +#![allow(const_err)] + +use std::cell::UnsafeCell; + +// this test ICEs to ensure that our mutability story is sound + +struct Meh { + x: &'static UnsafeCell, +} +unsafe impl Sync for Meh {} + +// the following will never be ok! no interior mut behind consts, because +// all allocs interned here will be marked immutable. +const MUH: Meh = Meh { //~ ERROR: mutable memory (`UnsafeCell`) is not allowed in constant + x: &UnsafeCell::new(42), +}; + +struct Synced { + x: UnsafeCell, +} +unsafe impl Sync for Synced {} + +// Make sure we also catch this behind a type-erased `dyn Trait` reference. +const SNEAKY: &dyn Sync = &Synced { x: UnsafeCell::new(42) }; +//~^ ERROR: mutable memory (`UnsafeCell`) is not allowed in constant + +// Make sure we also catch mutable references. +const BLUNT: &mut i32 = &mut 42; +//~^ ERROR: mutable memory (`&mut`) is not allowed in constant + +fn main() { + unsafe { + *MUH.x.get() = 99; + } +} diff --git a/src/test/ui/consts/miri_unleashed/mutable_references_err.stderr b/src/test/ui/consts/miri_unleashed/mutable_references_err.stderr new file mode 100644 index 000000000000..45e7d5a2cc3b --- /dev/null +++ b/src/test/ui/consts/miri_unleashed/mutable_references_err.stderr @@ -0,0 +1,40 @@ +error: mutable memory (`UnsafeCell`) is not allowed in constant + --> $DIR/mutable_references_err.rs:16:1 + | +LL | / const MUH: Meh = Meh { +LL | | x: &UnsafeCell::new(42), +LL | | }; + | |__^ + +error: mutable memory (`UnsafeCell`) is not allowed in constant + --> $DIR/mutable_references_err.rs:26:1 + | +LL | const SNEAKY: &dyn Sync = &Synced { x: UnsafeCell::new(42) }; + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +error: mutable memory (`&mut`) is not allowed in constant + --> $DIR/mutable_references_err.rs:30:1 + | +LL | const BLUNT: &mut i32 = &mut 42; + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +warning: skipping const checks + | +help: skipping check that does not even have a feature gate + --> $DIR/mutable_references_err.rs:17:8 + | +LL | x: &UnsafeCell::new(42), + | ^^^^^^^^^^^^^^^^^^^^ +help: skipping check that does not even have a feature gate + --> $DIR/mutable_references_err.rs:26:27 + | +LL | const SNEAKY: &dyn Sync = &Synced { x: UnsafeCell::new(42) }; + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +help: skipping check for `const_mut_refs` feature + --> $DIR/mutable_references_err.rs:30:25 + | +LL | const BLUNT: &mut i32 = &mut 42; + | ^^^^^^^ + +error: aborting due to 3 previous errors; 1 warning emitted + diff --git a/src/test/ui/consts/miri_unleashed/mutable_references_ice.rs b/src/test/ui/consts/miri_unleashed/mutable_references_ice.rs deleted file mode 100644 index 7388aad2a9e5..000000000000 --- a/src/test/ui/consts/miri_unleashed/mutable_references_ice.rs +++ /dev/null @@ -1,29 +0,0 @@ -// compile-flags: -Zunleash-the-miri-inside-of-you -// failure-status: 101 -// rustc-env:RUST_BACKTRACE=0 -// normalize-stderr-test "note: rustc 1.* running on .*" -> "note: rustc VERSION running on TARGET" -// normalize-stderr-test "note: compiler flags: .*" -> "note: compiler flags: FLAGS" -// normalize-stderr-test "interpret/intern.rs:[0-9]+:[0-9]+" -> "interpret/intern.rs:LL:CC" - -#![allow(const_err)] - -use std::cell::UnsafeCell; - -// this test ICEs to ensure that our mutability story is sound - -struct Meh { - x: &'static UnsafeCell, -} - -unsafe impl Sync for Meh {} - -// the following will never be ok! -const MUH: Meh = Meh { - x: &UnsafeCell::new(42), -}; - -fn main() { - unsafe { - *MUH.x.get() = 99; - } -} diff --git a/src/test/ui/consts/miri_unleashed/mutable_references_ice.stderr b/src/test/ui/consts/miri_unleashed/mutable_references_ice.stderr deleted file mode 100644 index 7ddf77af4d3a..000000000000 --- a/src/test/ui/consts/miri_unleashed/mutable_references_ice.stderr +++ /dev/null @@ -1,25 +0,0 @@ -thread 'rustc' panicked at 'assertion failed: `(left != right)` - left: `Const`, - right: `Const`: UnsafeCells are not allowed behind references in constants. This should have been prevented statically by const qualification. If this were allowed one would be able to change a constant at one use site and other use sites could observe that mutation.', src/librustc_mir/interpret/intern.rs:LL:CC -note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace - -error: internal compiler error: unexpected panic - -note: the compiler unexpectedly panicked. this is a bug. - -note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports - -note: rustc VERSION running on TARGET - -note: compiler flags: FLAGS - -warning: skipping const checks - | -help: skipping check that does not even have a feature gate - --> $DIR/mutable_references_ice.rs:22:8 - | -LL | x: &UnsafeCell::new(42), - | ^^^^^^^^^^^^^^^^^^^^ - -warning: 1 warning emitted - diff --git a/src/test/ui/consts/miri_unleashed/raw_mutable_const.rs b/src/test/ui/consts/miri_unleashed/raw_mutable_const.rs new file mode 100644 index 000000000000..3d200e231733 --- /dev/null +++ b/src/test/ui/consts/miri_unleashed/raw_mutable_const.rs @@ -0,0 +1,12 @@ +// compile-flags: -Zunleash-the-miri-inside-of-you + +#![feature(const_raw_ptr_deref)] +#![feature(const_mut_refs)] +#![allow(const_err)] + +use std::cell::UnsafeCell; + +const MUTABLE_BEHIND_RAW: *mut i32 = &UnsafeCell::new(42) as *const _ as *mut _; +//~^ ERROR: untyped pointers are not allowed in constant + +fn main() {} diff --git a/src/test/ui/consts/miri_unleashed/raw_mutable_const.stderr b/src/test/ui/consts/miri_unleashed/raw_mutable_const.stderr new file mode 100644 index 000000000000..c6dbf086ec0e --- /dev/null +++ b/src/test/ui/consts/miri_unleashed/raw_mutable_const.stderr @@ -0,0 +1,16 @@ +error: untyped pointers are not allowed in constant + --> $DIR/raw_mutable_const.rs:9:1 + | +LL | const MUTABLE_BEHIND_RAW: *mut i32 = &UnsafeCell::new(42) as *const _ as *mut _; + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +warning: skipping const checks + | +help: skipping check that does not even have a feature gate + --> $DIR/raw_mutable_const.rs:9:38 + | +LL | const MUTABLE_BEHIND_RAW: *mut i32 = &UnsafeCell::new(42) as *const _ as *mut _; + | ^^^^^^^^^^^^^^^^^^^^ + +error: aborting due to previous error; 1 warning emitted + diff --git a/src/test/ui/consts/raw-ptr-const.rs b/src/test/ui/consts/raw-ptr-const.rs new file mode 100644 index 000000000000..00fad046b557 --- /dev/null +++ b/src/test/ui/consts/raw-ptr-const.rs @@ -0,0 +1,10 @@ +#![allow(const_err)] // make sure we hit the `delay_span_bug` + +// This is a regression test for a `delay_span_bug` during interning when a constant +// evaluates to a (non-dangling) raw pointer. For now this errors; potentially it +// could also be allowed. + +const CONST_RAW: *const Vec = &Vec::new() as *const _; +//~^ ERROR untyped pointers are not allowed in constant + +fn main() {} diff --git a/src/test/ui/consts/raw-ptr-const.stderr b/src/test/ui/consts/raw-ptr-const.stderr new file mode 100644 index 000000000000..974b1c3ff45b --- /dev/null +++ b/src/test/ui/consts/raw-ptr-const.stderr @@ -0,0 +1,8 @@ +error: untyped pointers are not allowed in constant + --> $DIR/raw-ptr-const.rs:7:1 + | +LL | const CONST_RAW: *const Vec = &Vec::new() as *const _; + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +error: aborting due to previous error +