1 files changed, 73 insertions, 0 deletions
diff --git a/compiler/rustc_middle/src/ty/cast.rs b/compiler/rustc_middle/src/ty/cast.rs
new file mode 100644
index 000000000..c4b743dd4
--- /dev/null
+++ b/compiler/rustc_middle/src/ty/cast.rs
@@ -0,0 +1,73 @@
+// Helpers for handling cast expressions, used in both
+// typeck and codegen.
+
+use crate::ty::{self, Ty};
+
+use rustc_macros::HashStable;
+
+/// Types that are represented as ints.
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum IntTy {
+    U(ty::UintTy),
+    I,
+    CEnum,
+    Bool,
+    Char,
+}
+
+impl IntTy {
+    pub fn is_signed(self) -> bool {
+        matches!(self, Self::I)
+    }
+}
+
+// Valid types for the result of a non-coercion cast
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum CastTy<'tcx> {
+    /// Various types that are represented as ints and handled mostly
+    /// in the same way, merged for easier matching.
+    Int(IntTy),
+    /// Floating-point types.
+    Float,
+    /// Function pointers.
+    FnPtr,
+    /// Raw pointers.
+    Ptr(ty::TypeAndMut<'tcx>),
+}
+
+/// Cast Kind. See [RFC 401](https://rust-lang.github.io/rfcs/0401-coercions.html)
+/// (or librustc_typeck/check/cast.rs).
+#[derive(Copy, Clone, Debug, TyEncodable, TyDecodable, HashStable)]
+pub enum CastKind {
+    CoercionCast,
+    PtrPtrCast,
+    PtrAddrCast,
+    AddrPtrCast,
+    NumericCast,
+    EnumCast,
+    PrimIntCast,
+    U8CharCast,
+    ArrayPtrCast,
+    FnPtrPtrCast,
+    FnPtrAddrCast,
+}
+
+impl<'tcx> CastTy<'tcx> {
+    /// Returns `Some` for integral/pointer casts.
+    /// Casts like unsizing casts will return `None`.
+    pub fn from_ty(t: Ty<'tcx>) -> Option<CastTy<'tcx>> {
+        match *t.kind() {
+            ty::Bool => Some(CastTy::Int(IntTy::Bool)),
+            ty::Char => Some(CastTy::Int(IntTy::Char)),
+            ty::Int(_) => Some(CastTy::Int(IntTy::I)),
+            ty::Infer(ty::InferTy::IntVar(_)) => Some(CastTy::Int(IntTy::I)),
+            ty::Infer(ty::InferTy::FloatVar(_)) => Some(CastTy::Float),
+            ty::Uint(u) => Some(CastTy::Int(IntTy::U(u))),
+            ty::Float(_) => Some(CastTy::Float),
+            ty::Adt(d, _) if d.is_enum() && d.is_payloadfree() => Some(CastTy::Int(IntTy::CEnum)),
+            ty::RawPtr(mt) => Some(CastTy::Ptr(mt)),
+            ty::FnPtr(..) => Some(CastTy::FnPtr),
+            _ => None,
+        }
+    }
+}