rustc_middle/ty/
cast.rs

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1// Helpers for handling cast expressions, used in both
2// typeck and codegen.
3
4use rustc_macros::{HashStable, TyDecodable, TyEncodable};
5
6use crate::mir;
7use crate::ty::{self, Ty};
8
9/// Types that are represented as ints.
10#[derive(Copy, Clone, Debug, PartialEq, Eq)]
11pub enum IntTy {
12    U(ty::UintTy),
13    I,
14    CEnum,
15    Bool,
16    Char,
17}
18
19impl IntTy {
20    pub fn is_signed(self) -> bool {
21        matches!(self, Self::I)
22    }
23}
24
25// Valid types for the result of a non-coercion cast
26#[derive(Copy, Clone, Debug, PartialEq, Eq)]
27pub enum CastTy<'tcx> {
28    /// Various types that are represented as ints and handled mostly
29    /// in the same way, merged for easier matching.
30    Int(IntTy),
31    /// Floating-point types.
32    Float,
33    /// Function pointers.
34    FnPtr,
35    /// Raw pointers.
36    Ptr(ty::TypeAndMut<'tcx>),
37}
38
39/// Cast Kind. See [RFC 401](https://rust-lang.github.io/rfcs/0401-coercions.html)
40/// (or rustc_hir_analysis/check/cast.rs).
41#[derive(Copy, Clone, Debug, TyEncodable, TyDecodable, HashStable)]
42pub enum CastKind {
43    PtrPtrCast,
44    PtrAddrCast,
45    AddrPtrCast,
46    NumericCast,
47    EnumCast,
48    PrimIntCast,
49    U8CharCast,
50    ArrayPtrCast,
51    FnPtrPtrCast,
52    FnPtrAddrCast,
53}
54
55impl<'tcx> CastTy<'tcx> {
56    /// Returns `Some` for integral/pointer casts.
57    /// Casts like unsizing casts will return `None`.
58    pub fn from_ty(t: Ty<'tcx>) -> Option<CastTy<'tcx>> {
59        match *t.kind() {
60            ty::Bool => Some(CastTy::Int(IntTy::Bool)),
61            ty::Char => Some(CastTy::Int(IntTy::Char)),
62            ty::Int(_) => Some(CastTy::Int(IntTy::I)),
63            ty::Infer(ty::InferTy::IntVar(_)) => Some(CastTy::Int(IntTy::I)),
64            ty::Infer(ty::InferTy::FloatVar(_)) => Some(CastTy::Float),
65            ty::Uint(u) => Some(CastTy::Int(IntTy::U(u))),
66            ty::Float(_) => Some(CastTy::Float),
67            ty::Adt(d, _) if d.is_enum() && d.is_payloadfree() => Some(CastTy::Int(IntTy::CEnum)),
68            ty::RawPtr(ty, mutbl) => Some(CastTy::Ptr(ty::TypeAndMut { ty, mutbl })),
69            ty::FnPtr(..) => Some(CastTy::FnPtr),
70            _ => None,
71        }
72    }
73}
74
75/// Returns `mir::CastKind` from the given parameters.
76pub fn mir_cast_kind<'tcx>(from_ty: Ty<'tcx>, cast_ty: Ty<'tcx>) -> mir::CastKind {
77    let from = CastTy::from_ty(from_ty);
78    let cast = CastTy::from_ty(cast_ty);
79    let cast_kind = match (from, cast) {
80        (Some(CastTy::Ptr(_) | CastTy::FnPtr), Some(CastTy::Int(_))) => {
81            mir::CastKind::PointerExposeProvenance
82        }
83        (Some(CastTy::Int(_)), Some(CastTy::Ptr(_))) => mir::CastKind::PointerWithExposedProvenance,
84        (Some(CastTy::Int(_)), Some(CastTy::Int(_))) => mir::CastKind::IntToInt,
85        (Some(CastTy::FnPtr), Some(CastTy::Ptr(_))) => mir::CastKind::FnPtrToPtr,
86
87        (Some(CastTy::Float), Some(CastTy::Int(_))) => mir::CastKind::FloatToInt,
88        (Some(CastTy::Int(_)), Some(CastTy::Float)) => mir::CastKind::IntToFloat,
89        (Some(CastTy::Float), Some(CastTy::Float)) => mir::CastKind::FloatToFloat,
90        (Some(CastTy::Ptr(_)), Some(CastTy::Ptr(_))) => mir::CastKind::PtrToPtr,
91
92        (_, _) => {
93            bug!("Attempting to cast non-castable types {:?} and {:?}", from_ty, cast_ty)
94        }
95    };
96    cast_kind
97}
rustc_middle/ty/cast.rs

rustc_middle/ty/
cast.rs
