-#[instrument(skip(tcx, lit_input))]
-pub(crate) fn lit_to_mir_constant<'tcx>(
- tcx: TyCtxt<'tcx>,
- lit_input: LitToConstInput<'tcx>,
-) -> Result<ConstantKind<'tcx>, LitToConstError> {
- let LitToConstInput { lit, ty, neg } = lit_input;
- let trunc = |n| {
- let param_ty = ty::ParamEnv::reveal_all().and(ty);
- let width = tcx.layout_of(param_ty).map_err(|_| LitToConstError::Reported)?.size;
- trace!("trunc {} with size {} and shift {}", n, width.bits(), 128 - width.bits());
- let result = width.truncate(n);
- trace!("trunc result: {}", result);
- Ok(ConstValue::Scalar(Scalar::from_uint(result, width)))
- };
-
- let value = match (lit, &ty.kind()) {
- (ast::LitKind::Str(s, _), ty::Ref(_, inner_ty, _)) if inner_ty.is_str() => {
- let s = s.as_str();
- let allocation = Allocation::from_bytes_byte_aligned_immutable(s.as_bytes());
- let allocation = tcx.intern_const_alloc(allocation);
- ConstValue::Slice { data: allocation, start: 0, end: s.len() }
- }
- (ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _))
- if matches!(inner_ty.kind(), ty::Slice(_)) =>
- {
- let allocation = Allocation::from_bytes_byte_aligned_immutable(data as &[u8]);
- let allocation = tcx.intern_const_alloc(allocation);
- ConstValue::Slice { data: allocation, start: 0, end: data.len() }
- }
- (ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _)) if inner_ty.is_array() => {
- let id = tcx.allocate_bytes(data);
- ConstValue::Scalar(Scalar::from_pointer(id.into(), &tcx))
- }
- (ast::LitKind::Byte(n), ty::Uint(ty::UintTy::U8)) => {
- ConstValue::Scalar(Scalar::from_uint(*n, Size::from_bytes(1)))
- }
- (ast::LitKind::Int(n, _), ty::Uint(_)) | (ast::LitKind::Int(n, _), ty::Int(_)) => {
- trunc(if neg { (*n as i128).overflowing_neg().0 as u128 } else { *n })?
- }
- (ast::LitKind::Float(n, _), ty::Float(fty)) => {
- parse_float_into_constval(*n, *fty, neg).ok_or(LitToConstError::Reported)?
- }
- (ast::LitKind::Bool(b), ty::Bool) => ConstValue::Scalar(Scalar::from_bool(*b)),
- (ast::LitKind::Char(c), ty::Char) => ConstValue::Scalar(Scalar::from_char(*c)),
- (ast::LitKind::Err(_), _) => return Err(LitToConstError::Reported),
- _ => return Err(LitToConstError::TypeError),
- };
-
- Ok(ConstantKind::Val(value, ty))
-}
-