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fix: MIR eval mixed bit and byte sizes
MIR eval was using .bit_width() and then Size::from_bytes(), leading
to sizes that were out by a factor of 8. This led to crashes like
"expected int of size 64, but got size 8" during const eval.
I initially noticed this with u64 (a type of known size, so
.bit_size() returned a non-None value) but I've fixed all the bit/byte
mismatches in MIR evaluation.
Also added a unit test with a minimal repro of the case I originally
saw.
Fixes rust-lang/rust-analyzer#22593
AI disclosure: Partially written with Codex and GPT 5.5.
| -rw-r--r-- | crates/hir-ty/src/consteval/tests.rs | 13 | ||||
| -rw-r--r-- | crates/hir-ty/src/mir/eval.rs | 52 |
2 files changed, 44 insertions, 21 deletions
diff --git a/crates/hir-ty/src/consteval/tests.rs b/crates/hir-ty/src/consteval/tests.rs index 5421b97db2..0e51594a78 100644 --- a/crates/hir-ty/src/consteval/tests.rs +++ b/crates/hir-ty/src/consteval/tests.rs @@ -2634,6 +2634,19 @@ fn const_generic_subst_fn() { } #[test] +fn const_generic_fixed_width() { + check_number( + r#" + const fn m<const N: u64>() -> u64 { + N + } + const GOAL: u64 = m::<0>(); + "#, + 0, + ); +} + +#[test] fn layout_of_type_with_associated_type_field_defined_inside_body() { check_number( r#" diff --git a/crates/hir-ty/src/mir/eval.rs b/crates/hir-ty/src/mir/eval.rs index eb0e4c6020..c69febd019 100644 --- a/crates/hir-ty/src/mir/eval.rs +++ b/crates/hir-ty/src/mir/eval.rs @@ -1935,25 +1935,37 @@ impl<'a, 'db: 'a> Evaluator<'a, 'db> { Ok(Interval::new(addr, 4)) } TyKind::Int(int_ty) => { - let size = int_ty.bit_width().unwrap_or(self.ptr_size() as u64); - let value = valtree.inner().to_leaf().to_int(Size::from_bytes(size)); - let addr = self.heap_allocate(size as usize, size as usize)?; - self.write_memory(addr, &value.to_le_bytes()[..size as usize])?; - Ok(Interval::new(addr, size as usize)) + let size = int_ty + .bit_width() + .map(Size::from_bits) + .unwrap_or_else(|| Size::from_bytes(self.ptr_size() as u64)); + let bytes = size.bytes_usize(); + + let value = valtree.inner().to_leaf().to_int(size); + let addr = self.heap_allocate(bytes, bytes)?; + self.write_memory(addr, &value.to_le_bytes()[..bytes])?; + Ok(Interval::new(addr, bytes)) } TyKind::Uint(uint_ty) => { - let size = uint_ty.bit_width().unwrap_or(self.ptr_size() as u64); - let value = valtree.inner().to_leaf().to_uint(Size::from_bytes(size)); - let addr = self.heap_allocate(size as usize, size as usize)?; - self.write_memory(addr, &value.to_le_bytes()[..size as usize])?; - Ok(Interval::new(addr, size as usize)) + let size = uint_ty + .bit_width() + .map(Size::from_bits) + .unwrap_or_else(|| Size::from_bytes(self.ptr_size() as u64)); + let bytes = size.bytes_usize(); + + let value = valtree.inner().to_leaf().to_uint(size); + let addr = self.heap_allocate(bytes, bytes)?; + self.write_memory(addr, &value.to_le_bytes()[..bytes])?; + Ok(Interval::new(addr, bytes)) } TyKind::Float(float_ty) => { - let size = float_ty.bit_width(); - let value = valtree.inner().to_leaf().to_uint(Size::from_bytes(size)); - let addr = self.heap_allocate(size as usize, size as usize)?; - self.write_memory(addr, &value.to_le_bytes()[..size as usize])?; - Ok(Interval::new(addr, size as usize)) + let size = Size::from_bits(float_ty.bit_width()); + let bytes = size.bytes_usize(); + + let value = valtree.inner().to_leaf().to_uint(size); + let addr = self.heap_allocate(bytes, bytes)?; + self.write_memory(addr, &value.to_le_bytes()[..bytes])?; + Ok(Interval::new(addr, bytes)) } TyKind::RawPtr(..) => { let size = self.ptr_size(); @@ -1995,15 +2007,13 @@ impl<'a, 'db: 'a> Evaluator<'a, 'db> { _ => not_supported!("unsupported const"), }) .collect::<Result<'_, Vec<_>>>()?; + let item_size = item_layout.size.bytes_usize(); let items_addr = self.heap_allocate( - items.len() * (item_layout.size.bits() as usize), - item_layout.align.bits_usize(), + items.len() * item_size, + item_layout.align.bytes() as usize, )?; for (i, item) in items.iter().enumerate() { - self.copy_from_interval( - items_addr.offset(i * (item_layout.size.bits() as usize)), - *item, - )?; + self.copy_from_interval(items_addr.offset(i * item_size), *item)?; } let ref_addr = self.heap_allocate(self.ptr_size() * 2, self.ptr_size())?; self.write_memory(ref_addr, &items_addr.to_bytes())?; |