2 use rustc::ty::{self, Ty, TyCtxt, ParamEnv, layout::Size};
3 use syntax_pos::symbol::Symbol;
4 use rustc::mir::interpret::{ConstValue, Scalar};
7 crate enum LitToConstError {
12 crate fn lit_to_const<'tcx>(
13 lit: &'tcx ast::LitKind,
17 ) -> Result<&'tcx ty::Const<'tcx>, LitToConstError> {
21 let param_ty = ParamEnv::reveal_all().and(ty);
22 let width = tcx.layout_of(param_ty).map_err(|_| LitToConstError::Reported)?.size;
23 trace!("trunc {} with size {} and shift {}", n, width.bits(), 128 - width.bits());
24 let result = truncate(n, width);
25 trace!("trunc result: {}", result);
26 Ok(ConstValue::Scalar(Scalar::from_uint(result, width)))
29 use rustc::mir::interpret::*;
30 let lit = match *lit {
31 LitKind::Str(ref s, _) => {
33 let allocation = Allocation::from_byte_aligned_bytes(s.as_bytes());
34 let allocation = tcx.intern_const_alloc(allocation);
35 ConstValue::Slice { data: allocation, start: 0, end: s.len() }
37 LitKind::ByteStr(ref data) => {
38 let id = tcx.allocate_bytes(data);
39 ConstValue::Scalar(Scalar::Ptr(id.into()))
41 LitKind::Byte(n) => ConstValue::Scalar(Scalar::from_uint(n, Size::from_bytes(1))),
42 LitKind::Int(n, _) if neg => {
44 let n = n.overflowing_neg().0;
47 LitKind::Int(n, _) => trunc(n)?,
48 LitKind::Float(n, fty) => {
49 parse_float(n, fty, neg).map_err(|_| LitToConstError::UnparseableFloat)?
51 LitKind::FloatUnsuffixed(n) => {
52 let fty = match ty.kind {
53 ty::Float(fty) => fty,
56 parse_float(n, fty, neg).map_err(|_| LitToConstError::UnparseableFloat)?
58 LitKind::Bool(b) => ConstValue::Scalar(Scalar::from_bool(b)),
59 LitKind::Char(c) => ConstValue::Scalar(Scalar::from_char(c)),
60 LitKind::Err(_) => unreachable!(),
62 Ok(tcx.mk_const(ty::Const { val: lit, ty }))
69 ) -> Result<ConstValue<'tcx>, ()> {
70 let num = num.as_str();
71 use rustc_apfloat::ieee::{Single, Double};
72 let scalar = match fty {
73 ast::FloatTy::F32 => {
74 num.parse::<f32>().map_err(|_| ())?;
75 let mut f = num.parse::<Single>().unwrap_or_else(|e| {
76 panic!("apfloat::ieee::Single failed to parse `{}`: {:?}", num, e)
83 ast::FloatTy::F64 => {
84 num.parse::<f64>().map_err(|_| ())?;
85 let mut f = num.parse::<Double>().unwrap_or_else(|e| {
86 panic!("apfloat::ieee::Double failed to parse `{}`: {:?}", num, e)
95 Ok(ConstValue::Scalar(scalar))