diff options
18 files changed, 49 insertions, 32 deletions
diff --git a/compiler/rustc_const_eval/src/const_eval/machine.rs b/compiler/rustc_const_eval/src/const_eval/machine.rs index 4e952b043fb..0a6bdef2225 100644 --- a/compiler/rustc_const_eval/src/const_eval/machine.rs +++ b/compiler/rustc_const_eval/src/const_eval/machine.rs @@ -169,7 +169,11 @@ pub type CompileTimeInterpCx<'tcx> = InterpCx<'tcx, CompileTimeMachine<'tcx>>; #[derive(Debug, PartialEq, Eq, Copy, Clone)] pub enum MemoryKind { - Heap { was_made_global: bool }, + Heap { + /// Indicates whether `make_global` was called on this allocation. + /// If this is `true`, the allocation must be immutable. + was_made_global: bool, + }, } impl fmt::Display for MemoryKind { diff --git a/compiler/rustc_const_eval/src/interpret/intern.rs b/compiler/rustc_const_eval/src/interpret/intern.rs index 85524949053..b8fcdc9b7ef 100644 --- a/compiler/rustc_const_eval/src/interpret/intern.rs +++ b/compiler/rustc_const_eval/src/interpret/intern.rs @@ -106,13 +106,12 @@ fn intern_shallow<'tcx, T: CanIntern, M: CompileTimeMachine<'tcx, T>>( match kind { MemoryKind::Machine(x) if let Some(reason) = x.disallows_intern() => match reason { - // attempting to intern a `const_allocate`d pointer that was not made global via - // `const_make_global`. We emit an error here but don't return an `Err`. The `Err` - // is for pointers that we can't intern at all (i.e. dangling pointers). We still - // (recursively) intern this pointer because we don't have to worry about the - // additional paperwork involved with _not_ interning it, such as storing it in - // the dead memory map and having to deal with additional "dangling pointer" - // messages if someone tries to store the non-made-global ptr in the final value. + // Attempting to intern a `const_allocate`d pointer that was not made global via + // `const_make_global`. This is an error, but if we return `Err` now, things + // become inconsistent because we already removed the allocation from `alloc_map`. + // So instead we just emit an error and then continue interning as usual. + // We *could* do this check before removing the allocation from `alloc_map`, but then + // it would be much harder to ensure that we only error once for each allocation. DisallowInternReason::ConstHeap => { ecx.tcx.dcx().emit_err(ConstHeapPtrInFinal { span: ecx.tcx.span }); } diff --git a/compiler/rustc_const_eval/src/interpret/memory.rs b/compiler/rustc_const_eval/src/interpret/memory.rs index 08682dd193d..5f9f43a320b 100644 --- a/compiler/rustc_const_eval/src/interpret/memory.rs +++ b/compiler/rustc_const_eval/src/interpret/memory.rs @@ -312,7 +312,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> { interp_ok(new_ptr) } - /// mark the `const_allocate`d pointer immutable so we can intern it. + /// Mark the `const_allocate`d allocation `ptr` points to as immutable so we can intern it. pub fn make_const_heap_ptr_global( &mut self, ptr: Pointer<Option<CtfeProvenance>>, @@ -325,20 +325,19 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> { return Err(ConstEvalErrKind::ConstMakeGlobalWithOffset(ptr)).into(); } - let not_local_heap = - matches!(self.tcx.try_get_global_alloc(alloc_id), Some(GlobalAlloc::Memory(_))); - - if not_local_heap { + if matches!(self.tcx.try_get_global_alloc(alloc_id), Some(_)) { + // This points to something outside the current interpreter. return Err(ConstEvalErrKind::ConstMakeGlobalPtrIsNonHeap(ptr)).into(); } + // If we can't find it in `alloc_map` it must be dangling (because we don't use + // `extra_fn_ptr_map` in const-eval). let (kind, alloc) = self .memory .alloc_map .get_mut_or(alloc_id, || Err(ConstEvalErrKind::ConstMakeGlobalWithDanglingPtr(ptr)))?; - alloc.mutability = Mutability::Not; - + // Ensure this is actually a *heap* allocation, and record it as made-global. match kind { MemoryKind::Stack | MemoryKind::CallerLocation => { return Err(ConstEvalErrKind::ConstMakeGlobalPtrIsNonHeap(ptr)).into(); @@ -352,6 +351,9 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> { } } + // Prevent further mutation, this is now an immutable global. + alloc.mutability = Mutability::Not; + interp_ok(()) } diff --git a/compiler/rustc_const_eval/src/util/check_validity_requirement.rs b/compiler/rustc_const_eval/src/util/check_validity_requirement.rs index 1c2167a50fd..b1f29598750 100644 --- a/compiler/rustc_const_eval/src/util/check_validity_requirement.rs +++ b/compiler/rustc_const_eval/src/util/check_validity_requirement.rs @@ -52,6 +52,7 @@ fn check_validity_requirement_strict<'tcx>( let mut cx = InterpCx::new(cx.tcx(), DUMMY_SP, cx.typing_env, machine); + // It doesn't really matter which `MemoryKind` we use here, `Stack` is the least wrong. let allocated = cx.allocate(ty, MemoryKind::Stack).expect("OOM: failed to allocate for uninit check"); @@ -183,12 +184,10 @@ pub(crate) fn validate_scalar_in_layout<'tcx>( let Ok(layout) = cx.layout_of(ty) else { bug!("could not compute layout of {scalar:?}:{ty:?}") }; - let allocated = cx - .allocate( - layout, - MemoryKind::Machine(crate::const_eval::MemoryKind::Heap { was_made_global: false }), - ) - .expect("OOM: failed to allocate for uninit check"); + + // It doesn't really matter which `MemoryKind` we use here, `Stack` is the least wrong. + let allocated = + cx.allocate(layout, MemoryKind::Stack).expect("OOM: failed to allocate for uninit check"); cx.write_scalar(scalar, &allocated).unwrap(); diff --git a/tests/ui/consts/const-eval/heap/alloc_intrinsic_nontransient.rs b/tests/ui/consts/const-eval/heap/alloc_intrinsic_nontransient.rs index fa49990abfd..af24e463b50 100644 --- a/tests/ui/consts/const-eval/heap/alloc_intrinsic_nontransient.rs +++ b/tests/ui/consts/const-eval/heap/alloc_intrinsic_nontransient.rs @@ -12,7 +12,7 @@ const fn foo() -> &'static i32 { *i = 20; i }; - unsafe { &*(intrinsics::const_make_global(t as *mut u8) as *mut i32) } + unsafe { &*(intrinsics::const_make_global(t as *mut u8) as *const i32) } } fn main() { assert_eq!(*FOO, 20); diff --git a/tests/ui/consts/const-eval/heap/alloc_intrinsic_uninit.rs b/tests/ui/consts/const-eval/heap/alloc_intrinsic_uninit.rs index 2736cdeed8c..c54115de204 100644 --- a/tests/ui/consts/const-eval/heap/alloc_intrinsic_uninit.rs +++ b/tests/ui/consts/const-eval/heap/alloc_intrinsic_uninit.rs @@ -5,6 +5,7 @@ use std::intrinsics; const BAR: &i32 = unsafe { //~ ERROR: uninitialized memory - &*(intrinsics::const_make_global(intrinsics::const_allocate(4, 4)) as *mut i32) + // Make the pointer immutable to avoid errors related to mutable pointers in constants. + &*(intrinsics::const_make_global(intrinsics::const_allocate(4, 4)) as *const i32) }; fn main() {} diff --git a/tests/ui/consts/const-eval/heap/make-global-dangling.rs b/tests/ui/consts/const-eval/heap/make-global-dangling.rs index 4099e6e13ed..f4c5929bc41 100644 --- a/tests/ui/consts/const-eval/heap/make-global-dangling.rs +++ b/tests/ui/consts/const-eval/heap/make-global-dangling.rs @@ -1,3 +1,5 @@ +// Ensure that we can't call `const_make_global` on dangling pointers. + #![feature(core_intrinsics)] #![feature(const_heap)] diff --git a/tests/ui/consts/const-eval/heap/make-global-dangling.stderr b/tests/ui/consts/const-eval/heap/make-global-dangling.stderr index 4a5f59b9855..48c2796d0bf 100644 --- a/tests/ui/consts/const-eval/heap/make-global-dangling.stderr +++ b/tests/ui/consts/const-eval/heap/make-global-dangling.stderr @@ -1,11 +1,11 @@ error[E0080]: pointer not dereferenceable: pointer must point to some allocation, but got null pointer - --> $DIR/make-global-dangling.rs:7:8 + --> $DIR/make-global-dangling.rs:9:8 | LL | &*(intrinsics::const_make_global(std::ptr::null_mut()) as *const u32) | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `Y` failed here error[E0080]: pointer not dereferenceable: pointer must point to some allocation, but got 0x1[noalloc] which is a dangling pointer (it has no provenance) - --> $DIR/make-global-dangling.rs:12:8 + --> $DIR/make-global-dangling.rs:14:8 | LL | &*(intrinsics::const_make_global(std::ptr::dangling_mut()) as *const u32) | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `Z` failed here diff --git a/tests/ui/consts/const-eval/heap/make-global-other.rs b/tests/ui/consts/const-eval/heap/make-global-other.rs index dd5d27cc968..4e2a59de13e 100644 --- a/tests/ui/consts/const-eval/heap/make-global-other.rs +++ b/tests/ui/consts/const-eval/heap/make-global-other.rs @@ -1,3 +1,5 @@ +// Ensure that we can't call `const_make_global` on pointers not in the current interpreter. + #![feature(core_intrinsics)] #![feature(const_heap)] diff --git a/tests/ui/consts/const-eval/heap/make-global-other.stderr b/tests/ui/consts/const-eval/heap/make-global-other.stderr index 572230afe3b..ed0d768cf37 100644 --- a/tests/ui/consts/const-eval/heap/make-global-other.stderr +++ b/tests/ui/consts/const-eval/heap/make-global-other.stderr @@ -1,5 +1,5 @@ error[E0080]: pointer passed to `const_make_global` does not point to a heap allocation: ALLOC0<imm> - --> $DIR/make-global-other.rs:9:8 + --> $DIR/make-global-other.rs:11:8 | LL | &*(intrinsics::const_make_global(X as *const i32 as *mut u8) as *const i32) | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `Y` failed here diff --git a/tests/ui/consts/const-eval/heap/make-global-twice.rs b/tests/ui/consts/const-eval/heap/make-global-twice.rs index 36d779ad034..0cd617cea3e 100644 --- a/tests/ui/consts/const-eval/heap/make-global-twice.rs +++ b/tests/ui/consts/const-eval/heap/make-global-twice.rs @@ -1,3 +1,5 @@ +// Ensure that we can't call `const_make_global` twice. + #![feature(core_intrinsics)] #![feature(const_heap)] diff --git a/tests/ui/consts/const-eval/heap/make-global-twice.stderr b/tests/ui/consts/const-eval/heap/make-global-twice.stderr index 35d2385d9e0..95cdb9694d8 100644 --- a/tests/ui/consts/const-eval/heap/make-global-twice.stderr +++ b/tests/ui/consts/const-eval/heap/make-global-twice.stderr @@ -1,5 +1,5 @@ error[E0080]: attempting to call `const_make_global` twice on the same allocation ALLOC0 - --> $DIR/make-global-twice.rs:11:5 + --> $DIR/make-global-twice.rs:13:5 | LL | intrinsics::const_make_global(ptr); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `Y` failed here diff --git a/tests/ui/consts/const-eval/heap/ptr_made_global_mutated.rs b/tests/ui/consts/const-eval/heap/ptr_made_global_mutated.rs index 75f2d87d4d0..bea2a5949c2 100644 --- a/tests/ui/consts/const-eval/heap/ptr_made_global_mutated.rs +++ b/tests/ui/consts/const-eval/heap/ptr_made_global_mutated.rs @@ -1,3 +1,4 @@ +// Ensure that once an allocation is "made global", we can no longer mutate it. #![feature(core_intrinsics)] #![feature(const_heap)] use std::intrinsics; diff --git a/tests/ui/consts/const-eval/heap/ptr_made_global_mutated.stderr b/tests/ui/consts/const-eval/heap/ptr_made_global_mutated.stderr index 15af44b74d5..0e88ea77d1c 100644 --- a/tests/ui/consts/const-eval/heap/ptr_made_global_mutated.stderr +++ b/tests/ui/consts/const-eval/heap/ptr_made_global_mutated.stderr @@ -1,5 +1,5 @@ error[E0080]: writing to ALLOC0 which is read-only - --> $DIR/ptr_made_global_mutated.rs:9:5 + --> $DIR/ptr_made_global_mutated.rs:10:5 | LL | *(ptr as *mut u8) = 2; | ^^^^^^^^^^^^^^^^^^^^^ evaluation of `A` failed here diff --git a/tests/ui/consts/const-eval/heap/ptr_not_made_global.rs b/tests/ui/consts/const-eval/heap/ptr_not_made_global.rs index 4b0499d4106..6980e92c218 100644 --- a/tests/ui/consts/const-eval/heap/ptr_not_made_global.rs +++ b/tests/ui/consts/const-eval/heap/ptr_not_made_global.rs @@ -1,3 +1,8 @@ +// Ensure that we reject interning `const_allocate`d allocations in the final value of constants +// if they have not been made global through `const_make_global`. The pointers are made *immutable* +// to focus the test on the missing `make_global`; `ptr_not_made_global_mut.rs` covers the case +// where the pointer remains mutable. + #![feature(core_intrinsics)] #![feature(const_heap)] use std::intrinsics; diff --git a/tests/ui/consts/const-eval/heap/ptr_not_made_global.stderr b/tests/ui/consts/const-eval/heap/ptr_not_made_global.stderr index 569a8be3e8c..cb2bb1e8cd8 100644 --- a/tests/ui/consts/const-eval/heap/ptr_not_made_global.stderr +++ b/tests/ui/consts/const-eval/heap/ptr_not_made_global.stderr @@ -1,5 +1,5 @@ error: encountered `const_allocate` pointer in final value that was not made global - --> $DIR/ptr_not_made_global.rs:5:1 + --> $DIR/ptr_not_made_global.rs:10:1 | LL | const FOO: &i32 = foo(); | ^^^^^^^^^^^^^^^ @@ -7,7 +7,7 @@ LL | const FOO: &i32 = foo(); = note: use `const_make_global` to make allocated pointers immutable before returning error: encountered `const_allocate` pointer in final value that was not made global - --> $DIR/ptr_not_made_global.rs:7:1 + --> $DIR/ptr_not_made_global.rs:12:1 | LL | const FOO_RAW: *const i32 = foo(); | ^^^^^^^^^^^^^^^^^^^^^^^^^ diff --git a/tests/ui/consts/const-eval/heap/alloc_intrinsic_untyped.rs b/tests/ui/consts/const-eval/heap/ptr_not_made_global_mut.rs index 201fa715022..201fa715022 100644 --- a/tests/ui/consts/const-eval/heap/alloc_intrinsic_untyped.rs +++ b/tests/ui/consts/const-eval/heap/ptr_not_made_global_mut.rs diff --git a/tests/ui/consts/const-eval/heap/alloc_intrinsic_untyped.stderr b/tests/ui/consts/const-eval/heap/ptr_not_made_global_mut.stderr index e69d27e48c8..eae79d24797 100644 --- a/tests/ui/consts/const-eval/heap/alloc_intrinsic_untyped.stderr +++ b/tests/ui/consts/const-eval/heap/ptr_not_made_global_mut.stderr @@ -1,5 +1,5 @@ error: encountered `const_allocate` pointer in final value that was not made global - --> $DIR/alloc_intrinsic_untyped.rs:8:1 + --> $DIR/ptr_not_made_global_mut.rs:8:1 | LL | const BAR: *mut i32 = unsafe { intrinsics::const_allocate(4, 4) as *mut i32 }; | ^^^^^^^^^^^^^^^^^^^ @@ -7,7 +7,7 @@ LL | const BAR: *mut i32 = unsafe { intrinsics::const_allocate(4, 4) as *mut i32 = note: use `const_make_global` to make allocated pointers immutable before returning error: encountered mutable pointer in final value of constant - --> $DIR/alloc_intrinsic_untyped.rs:8:1 + --> $DIR/ptr_not_made_global_mut.rs:8:1 | LL | const BAR: *mut i32 = unsafe { intrinsics::const_allocate(4, 4) as *mut i32 }; | ^^^^^^^^^^^^^^^^^^^ |