fix len() on non-array but array-layout types (e.g. SIMD)

src/librustc_mir/interpret/place.rs

@@ -137,19 +137,20 @@ impl<'tcx> MPlaceTy<'tcx> {
 
  #[inline]
  pub(super) fn len(self, cx: impl HasDataLayout) -> EvalResult<'tcx, u64> {
- match self.layout.ty.sty {
- ty::Array(..) => {
- // Sized, get length from layout.
- debug_assert!(self.extra.is_none());
- match self.layout.fields {
- layout::FieldPlacement::Array { count, .. } => Ok(count),
- _ => bug!("Length for non-array layout {:?} requested", self.layout),
- }
+ if self.layout.is_unsized() {
+ // We need to consult `extra` metadata
+ match self.layout.ty.sty {
+ ty::Slice(..) | ty::Str =>
+ return self.extra.unwrap().to_usize(cx),
+ _ => bug!("len not supported on unsized type {:?}", self.layout.ty),
  }
- ty::Slice(..) | ty::Str => {
- self.extra.unwrap().to_usize(cx)
+ } else {
+ // Go through the layout. There are lots of types that support a length,
+ // e.g. SIMD types.
+ match self.layout.fields {
+ layout::FieldPlacement::Array { count, .. } => Ok(count),
+ _ => bug!("len not supported on sized type {:?}", self.layout.ty),
  }
- _ => bug!("len not supported on type {:?}", self.layout.ty),
  }
  }
 

src/librustc_mir/interpret/validity.rs

@@ -332,16 +332,16 @@ impl<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M> {
  }
  }
  }
- ty::Array(..) | ty::Slice(..) => {
- // This handles the unsized case correctly as well
+ _ => {
+ // This handles the unsized case correctly as well, as well as
+ // SIMD an all sorts of other array-like types.
  for (i, field) in self.mplace_array_fields(dest)?.enumerate() {
  let field = field?;
  path.push(PathElem::ArrayElem(i));
  self.validate_operand(field.into(), path, seen, todo)?;
  path.truncate(path_len);
  }
  }
- _ => bug!("Array layout for non-array type {:?}", dest.layout.ty),
  }
  },
  layout::FieldPlacement::Array { .. } => {