From 78b680e14a287a98ec0501116607bb49b31c9f28 Mon Sep 17 00:00:00 2001 From: Ralf Jung Date: Sat, 26 Mar 2022 13:03:49 -0400 Subject: [PATCH 1/2] interpret: mark a dead match arm as dead --- compiler/rustc_const_eval/src/interpret/eval_context.rs | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/compiler/rustc_const_eval/src/interpret/eval_context.rs b/compiler/rustc_const_eval/src/interpret/eval_context.rs index d78c7a9fad983..abd7094440e57 100644 --- a/compiler/rustc_const_eval/src/interpret/eval_context.rs +++ b/compiler/rustc_const_eval/src/interpret/eval_context.rs @@ -444,6 +444,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { match scalar.try_to_int() { Ok(int) => int.is_null(), Err(_) => { + // Can only happen during CTFE. let ptr = self.scalar_to_ptr(scalar); match self.memory.ptr_try_get_alloc(ptr) { Ok((alloc_id, offset, _)) => { @@ -455,7 +456,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { // Note that one-past-the-end (offset == size) is still inbounds, and never null. offset > size } - Err(offset) => offset == 0, + Err(_offset) => bug!("a non-int scalar is always a pointer"), } } } From 3bbcf64fb33e701084c664d9b691ac3c1736bd14 Mon Sep 17 00:00:00 2001 From: Ralf Jung Date: Sat, 26 Mar 2022 13:17:49 -0400 Subject: [PATCH 2/2] interpret: with enforce_number_validity, ensure integers are truly Scalar::Int (i.e., no pointers) --- compiler/rustc_const_eval/src/interpret/validity.rs | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/compiler/rustc_const_eval/src/interpret/validity.rs b/compiler/rustc_const_eval/src/interpret/validity.rs index 8bdafa8762386..9da7f5e30cb9e 100644 --- a/compiler/rustc_const_eval/src/interpret/validity.rs +++ b/compiler/rustc_const_eval/src/interpret/validity.rs @@ -21,7 +21,7 @@ use std::hash::Hash; use super::{ alloc_range, CheckInAllocMsg, GlobalAlloc, InterpCx, InterpResult, MPlaceTy, Machine, - MemPlaceMeta, OpTy, ScalarMaybeUninit, ValueVisitor, + MemPlaceMeta, OpTy, Scalar, ScalarMaybeUninit, ValueVisitor, }; macro_rules! throw_validation_failure { @@ -521,8 +521,11 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, ' // NOTE: Keep this in sync with the array optimization for int/float // types below! if M::enforce_number_validity(self.ecx) { - // Integers/floats in CTFE: Must be scalar bits, pointers are dangerous - let is_bits = value.check_init().map_or(false, |v| v.try_to_int().is_ok()); + // Integers/floats with number validity: Must be scalar bits, pointers are dangerous. + // As a special exception we *do* match on a `Scalar` here, since we truly want + // to know its underlying representation (and *not* cast it to an integer). + let is_bits = + value.check_init().map_or(false, |v| matches!(v, Scalar::Int(..))); if !is_bits { throw_validation_failure!(self.path, { "{:x}", value } expected { "initialized plain (non-pointer) bytes" }