2 use rustc::ty::{self, Ty, TyCtxt, ParamEnv};
3 use syntax_pos::symbol::Symbol;
4 use rustc::mir::interpret::{ConstValue, Scalar};
7 crate enum LitToConstError {
12 crate fn lit_to_const<'a, 'gcx, 'tcx>(
13 lit: &'tcx ast::LitKind,
14 tcx: TyCtxt<'a, 'gcx, 'tcx>,
17 ) -> Result<ty::Const<'tcx>, LitToConstError> {
21 let param_ty = ParamEnv::reveal_all().and(tcx.lift_to_global(&ty).unwrap());
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::Bits {
28 size: width.bytes() as u8,
32 use rustc::mir::interpret::*;
33 let lit = match *lit {
34 LitKind::Str(ref s, _) => {
36 let id = tcx.allocate_bytes(s.as_bytes());
37 ConstValue::new_slice(Scalar::Ptr(id.into()), s.len() as u64)
39 LitKind::Err(ref s) => {
41 let id = tcx.allocate_bytes(s.as_bytes());
43 val: ConstValue::new_slice(Scalar::Ptr(id.into()), s.len() as u64),
47 LitKind::ByteStr(ref data) => {
48 let id = tcx.allocate_bytes(data);
49 ConstValue::Scalar(Scalar::Ptr(id.into()))
51 LitKind::Byte(n) => ConstValue::Scalar(Scalar::Bits {
55 LitKind::Int(n, _) if neg => {
57 let n = n.overflowing_neg().0;
60 LitKind::Int(n, _) => trunc(n)?,
61 LitKind::Float(n, fty) => {
62 parse_float(n, fty, neg).map_err(|_| LitToConstError::UnparseableFloat)?
64 LitKind::FloatUnsuffixed(n) => {
65 let fty = match ty.sty {
66 ty::Float(fty) => fty,
69 parse_float(n, fty, neg).map_err(|_| LitToConstError::UnparseableFloat)?
71 LitKind::Bool(b) => ConstValue::Scalar(Scalar::from_bool(b)),
72 LitKind::Char(c) => ConstValue::Scalar(Scalar::from_char(c)),
74 Ok(ty::Const { val: lit, ty })
81 ) -> Result<ConstValue<'tcx>, ()> {
82 let num = num.as_str();
83 use rustc_apfloat::ieee::{Single, Double};
84 use rustc_apfloat::Float;
85 let (bits, size) = match fty {
86 ast::FloatTy::F32 => {
87 num.parse::<f32>().map_err(|_| ())?;
88 let mut f = num.parse::<Single>().unwrap_or_else(|e| {
89 panic!("apfloat::ieee::Single failed to parse `{}`: {:?}", num, e)
96 ast::FloatTy::F64 => {
97 num.parse::<f64>().map_err(|_| ())?;
98 let mut f = num.parse::<Double>().unwrap_or_else(|e| {
99 panic!("apfloat::ieee::Single failed to parse `{}`: {:?}", num, e)
108 Ok(ConstValue::Scalar(Scalar::Bits { bits, size }))