compiler/rustc_middle/src/ty/consts.rs - rust-lang/rust - Git at Google

 use std::borrow::Cow;

 use rustc_data_structures::intern::Interned;
 use rustc_error_messages::MultiSpan;
 use rustc_macros::{HashStable, TyDecodable, TyEncodable};
 use rustc_type_ir::walk::TypeWalker;
 use rustc_type_ir::{self as ir, TypeFlags, WithCachedTypeInfo};

 use crate::ty::{self, Ty, TyCtxt};

 mod int;
 mod kind;
 mod valtree;

 pub use int::*;
 pub use kind::*;
 use rustc_span::{DUMMY_SP, ErrorGuaranteed};
 pub use valtree::*;

 pub type ConstKind<'tcx> = ir::ConstKind<TyCtxt<'tcx>>;
 pub type UnevaluatedConst<'tcx> = ir::UnevaluatedConst<TyCtxt<'tcx>>;

 #[cfg(target_pointer_width = "64")]
 rustc_data_structures::static_assert_size!(ConstKind<'_>, 24);

 #[derive(Copy, Clone, PartialEq, Eq, Hash, HashStable)]
 #[rustc_pass_by_value]
 pub struct Const<'tcx>(pub(super) Interned<'tcx, WithCachedTypeInfo<ConstKind<'tcx>>>);

 impl<'tcx> rustc_type_ir::inherent::IntoKind for Const<'tcx> {
     type Kind = ConstKind<'tcx>;

     fn kind(self) -> ConstKind<'tcx> {
         self.kind()
     }
 }

 impl<'tcx> rustc_type_ir::Flags for Const<'tcx> {
     fn flags(&self) -> TypeFlags {
         self.0.flags
     }

     fn outer_exclusive_binder(&self) -> rustc_type_ir::DebruijnIndex {
         self.0.outer_exclusive_binder
     }
 }

 impl<'tcx> Const<'tcx> {
     #[inline]
     pub fn kind(self) -> ConstKind<'tcx> {
         let a: &ConstKind<'tcx> = self.0.0;
         *a
     }

     // FIXME(compiler-errors): Think about removing this.
     #[inline]
     pub fn flags(self) -> TypeFlags {
         self.0.flags
     }

     // FIXME(compiler-errors): Think about removing this.
     #[inline]
     pub fn outer_exclusive_binder(self) -> ty::DebruijnIndex {
         self.0.outer_exclusive_binder
     }

     #[inline]
     pub fn new(tcx: TyCtxt<'tcx>, kind: ty::ConstKind<'tcx>) -> Const<'tcx> {
         tcx.mk_ct_from_kind(kind)
     }

     #[inline]
     pub fn new_param(tcx: TyCtxt<'tcx>, param: ty::ParamConst) -> Const<'tcx> {
         Const::new(tcx, ty::ConstKind::Param(param))
     }

     #[inline]
     pub fn new_var(tcx: TyCtxt<'tcx>, infer: ty::ConstVid) -> Const<'tcx> {
         Const::new(tcx, ty::ConstKind::Infer(ty::InferConst::Var(infer)))
     }

     #[inline]
     pub fn new_fresh(tcx: TyCtxt<'tcx>, fresh: u32) -> Const<'tcx> {
         Const::new(tcx, ty::ConstKind::Infer(ty::InferConst::Fresh(fresh)))
     }

     #[inline]
     pub fn new_infer(tcx: TyCtxt<'tcx>, infer: ty::InferConst) -> Const<'tcx> {
         Const::new(tcx, ty::ConstKind::Infer(infer))
     }

     #[inline]
     pub fn new_bound(
         tcx: TyCtxt<'tcx>,
         debruijn: ty::DebruijnIndex,
         bound_const: ty::BoundConst,
     ) -> Const<'tcx> {
         Const::new(tcx, ty::ConstKind::Bound(debruijn, bound_const))
     }

     #[inline]
     pub fn new_placeholder(tcx: TyCtxt<'tcx>, placeholder: ty::PlaceholderConst) -> Const<'tcx> {
         Const::new(tcx, ty::ConstKind::Placeholder(placeholder))
     }

     #[inline]
     pub fn new_unevaluated(tcx: TyCtxt<'tcx>, uv: ty::UnevaluatedConst<'tcx>) -> Const<'tcx> {
         tcx.debug_assert_args_compatible(uv.def, uv.args);
         Const::new(tcx, ty::ConstKind::Unevaluated(uv))
     }

     #[inline]
     pub fn new_value(tcx: TyCtxt<'tcx>, valtree: ty::ValTree<'tcx>, ty: Ty<'tcx>) -> Const<'tcx> {
         Const::new(tcx, ty::ConstKind::Value(ty::Value { ty, valtree }))
     }

     #[inline]
     pub fn new_expr(tcx: TyCtxt<'tcx>, expr: ty::Expr<'tcx>) -> Const<'tcx> {
         Const::new(tcx, ty::ConstKind::Expr(expr))
     }

     #[inline]
     pub fn new_error(tcx: TyCtxt<'tcx>, e: ty::ErrorGuaranteed) -> Const<'tcx> {
         Const::new(tcx, ty::ConstKind::Error(e))
     }

     /// Like [Ty::new_error] but for constants.
     #[track_caller]
     pub fn new_misc_error(tcx: TyCtxt<'tcx>) -> Const<'tcx> {
         Const::new_error_with_message(
             tcx,
             DUMMY_SP,
             "ty::ConstKind::Error constructed but no error reported",
         )
     }

     /// Like [Ty::new_error_with_message] but for constants.
     #[track_caller]
     pub fn new_error_with_message<S: Into<MultiSpan>>(
         tcx: TyCtxt<'tcx>,
         span: S,
         msg: impl Into<Cow<'static, str>>,
     ) -> Const<'tcx> {
         let reported = tcx.dcx().span_delayed_bug(span, msg);
         Const::new_error(tcx, reported)
     }

     pub fn is_trivially_wf(self) -> bool {
         match self.kind() {
             ty::ConstKind::Param(_) | ty::ConstKind::Placeholder(_) | ty::ConstKind::Bound(..) => {
                 true
             }
             ty::ConstKind::Infer(_)
             | ty::ConstKind::Unevaluated(..)
             | ty::ConstKind::Value(_)
             | ty::ConstKind::Error(_)
             | ty::ConstKind::Expr(_) => false,
         }
     }
 }

 impl<'tcx> rustc_type_ir::inherent::Const<TyCtxt<'tcx>> for Const<'tcx> {
     fn new_infer(tcx: TyCtxt<'tcx>, infer: ty::InferConst) -> Self {
         Const::new_infer(tcx, infer)
     }

     fn new_var(tcx: TyCtxt<'tcx>, vid: ty::ConstVid) -> Self {
         Const::new_var(tcx, vid)
     }

     fn new_bound(
         interner: TyCtxt<'tcx>,
         debruijn: ty::DebruijnIndex,
         bound_const: ty::BoundConst,
     ) -> Self {
         Const::new_bound(interner, debruijn, bound_const)
     }

     fn new_anon_bound(tcx: TyCtxt<'tcx>, debruijn: ty::DebruijnIndex, var: ty::BoundVar) -> Self {
         Const::new_bound(tcx, debruijn, ty::BoundConst { var })
     }

     fn new_placeholder(tcx: TyCtxt<'tcx>, placeholder: ty::PlaceholderConst) -> Self {
         Const::new_placeholder(tcx, placeholder)
     }

     fn new_unevaluated(interner: TyCtxt<'tcx>, uv: ty::UnevaluatedConst<'tcx>) -> Self {
         Const::new_unevaluated(interner, uv)
     }

     fn new_expr(interner: TyCtxt<'tcx>, expr: ty::Expr<'tcx>) -> Self {
         Const::new_expr(interner, expr)
     }

     fn new_error(interner: TyCtxt<'tcx>, guar: ErrorGuaranteed) -> Self {
         Const::new_error(interner, guar)
     }
 }

 impl<'tcx> Const<'tcx> {
     /// Creates a constant with the given integer value and interns it.
     #[inline]
     pub fn from_bits(
         tcx: TyCtxt<'tcx>,
         bits: u128,
         typing_env: ty::TypingEnv<'tcx>,
         ty: Ty<'tcx>,
     ) -> Self {
         let size = tcx
             .layout_of(typing_env.as_query_input(ty))
             .unwrap_or_else(|e| panic!("could not compute layout for {ty:?}: {e:?}"))
             .size;
         ty::Const::new_value(
             tcx,
             ty::ValTree::from_scalar_int(tcx, ScalarInt::try_from_uint(bits, size).unwrap()),
             ty,
         )
     }

     #[inline]
     /// Creates an interned zst constant.
     pub fn zero_sized(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Self {
         ty::Const::new_value(tcx, ty::ValTree::zst(tcx), ty)
     }

     #[inline]
     /// Creates an interned bool constant.
     pub fn from_bool(tcx: TyCtxt<'tcx>, v: bool) -> Self {
         Self::from_bits(tcx, v as u128, ty::TypingEnv::fully_monomorphized(), tcx.types.bool)
     }

     #[inline]
     /// Creates an interned usize constant.
     pub fn from_target_usize(tcx: TyCtxt<'tcx>, n: u64) -> Self {
         Self::from_bits(tcx, n as u128, ty::TypingEnv::fully_monomorphized(), tcx.types.usize)
     }

     /// Panics if `self.kind != ty::ConstKind::Value`.
     pub fn to_value(self) -> ty::Value<'tcx> {
         match self.kind() {
             ty::ConstKind::Value(cv) => cv,
             _ => bug!("expected ConstKind::Value, got {:?}", self.kind()),
         }
     }

     /// Attempts to convert to a value.
     ///
     /// Note that this does not evaluate the constant.
     pub fn try_to_value(self) -> Option<ty::Value<'tcx>> {
         match self.kind() {
             ty::ConstKind::Value(cv) => Some(cv),
             _ => None,
         }
     }

     /// Convenience method to extract the value of a usize constant,
     /// useful to get the length of an array type.
     ///
     /// Note that this does not evaluate the constant.
     #[inline]
     pub fn try_to_target_usize(self, tcx: TyCtxt<'tcx>) -> Option<u64> {
         self.try_to_value()?.try_to_target_usize(tcx)
     }

     pub fn is_ct_infer(self) -> bool {
         matches!(self.kind(), ty::ConstKind::Infer(_))
     }

     /// Iterator that walks `self` and any types reachable from
     /// `self`, in depth-first order. Note that just walks the types
     /// that appear in `self`, it does not descend into the fields of
     /// structs or variants. For example:
     ///
     /// ```text
     /// isize => { isize }
     /// Foo<Bar<isize>> => { Foo<Bar<isize>>, Bar<isize>, isize }
     /// [isize] => { [isize], isize }
     /// ```
     pub fn walk(self) -> TypeWalker<TyCtxt<'tcx>> {
         TypeWalker::new(self.into())
     }
 }

 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable, HashStable)]
 pub enum AnonConstKind {
     /// `feature(generic_const_exprs)` anon consts are allowed to use arbitrary generic parameters in scope
     GCE,
     /// stable `min_const_generics` anon consts are not allowed to use any generic parameters
     MCG,
     /// anon consts used as the length of a repeat expr are syntactically allowed to use generic parameters
     /// but must not depend on the actual instantiation. See #76200 for more information
     RepeatExprCount,
     /// anon consts outside of the type system, e.g. enum discriminants
     NonTypeSystem,
 }
	use std::borrow::Cow;

	use rustc_data_structures::intern::Interned;
	use rustc_error_messages::MultiSpan;
	use rustc_macros::{HashStable, TyDecodable, TyEncodable};
	use rustc_type_ir::walk::TypeWalker;
	use rustc_type_ir::{self as ir, TypeFlags, WithCachedTypeInfo};

	use crate::ty::{self, Ty, TyCtxt};

	mod int;
	mod kind;
	mod valtree;

	pub use int::*;
	pub use kind::*;
	use rustc_span::{DUMMY_SP, ErrorGuaranteed};
	pub use valtree::*;

	pub type ConstKind<'tcx> = ir::ConstKind<TyCtxt<'tcx>>;
	pub type UnevaluatedConst<'tcx> = ir::UnevaluatedConst<TyCtxt<'tcx>>;

	#[cfg(target_pointer_width = "64")]
	rustc_data_structures::static_assert_size!(ConstKind<'_>, 24);

	#[derive(Copy, Clone, PartialEq, Eq, Hash, HashStable)]
	#[rustc_pass_by_value]
	pub struct Const<'tcx>(pub(super) Interned<'tcx, WithCachedTypeInfo<ConstKind<'tcx>>>);

	impl<'tcx> rustc_type_ir::inherent::IntoKind for Const<'tcx> {
	type Kind = ConstKind<'tcx>;

	fn kind(self) -> ConstKind<'tcx> {
	self.kind()
	}
	}

	impl<'tcx> rustc_type_ir::Flags for Const<'tcx> {
	fn flags(&self) -> TypeFlags {
	self.0.flags
	}

	fn outer_exclusive_binder(&self) -> rustc_type_ir::DebruijnIndex {
	self.0.outer_exclusive_binder
	}
	}

	impl<'tcx> Const<'tcx> {
	#[inline]
	pub fn kind(self) -> ConstKind<'tcx> {
	let a: &ConstKind<'tcx> = self.0.0;
	*a
	}

	// FIXME(compiler-errors): Think about removing this.
	#[inline]
	pub fn flags(self) -> TypeFlags {
	self.0.flags
	}

	// FIXME(compiler-errors): Think about removing this.
	#[inline]
	pub fn outer_exclusive_binder(self) -> ty::DebruijnIndex {
	self.0.outer_exclusive_binder
	}

	#[inline]
	pub fn new(tcx: TyCtxt<'tcx>, kind: ty::ConstKind<'tcx>) -> Const<'tcx> {
	tcx.mk_ct_from_kind(kind)
	}

	#[inline]
	pub fn new_param(tcx: TyCtxt<'tcx>, param: ty::ParamConst) -> Const<'tcx> {
	Const::new(tcx, ty::ConstKind::Param(param))
	}

	#[inline]
	pub fn new_var(tcx: TyCtxt<'tcx>, infer: ty::ConstVid) -> Const<'tcx> {
	Const::new(tcx, ty::ConstKind::Infer(ty::InferConst::Var(infer)))
	}

	#[inline]
	pub fn new_fresh(tcx: TyCtxt<'tcx>, fresh: u32) -> Const<'tcx> {
	Const::new(tcx, ty::ConstKind::Infer(ty::InferConst::Fresh(fresh)))
	}

	#[inline]
	pub fn new_infer(tcx: TyCtxt<'tcx>, infer: ty::InferConst) -> Const<'tcx> {
	Const::new(tcx, ty::ConstKind::Infer(infer))
	}

	#[inline]
	pub fn new_bound(
	tcx: TyCtxt<'tcx>,
	debruijn: ty::DebruijnIndex,
	bound_const: ty::BoundConst,
	) -> Const<'tcx> {
	Const::new(tcx, ty::ConstKind::Bound(debruijn, bound_const))
	}

	#[inline]
	pub fn new_placeholder(tcx: TyCtxt<'tcx>, placeholder: ty::PlaceholderConst) -> Const<'tcx> {
	Const::new(tcx, ty::ConstKind::Placeholder(placeholder))
	}

	#[inline]
	pub fn new_unevaluated(tcx: TyCtxt<'tcx>, uv: ty::UnevaluatedConst<'tcx>) -> Const<'tcx> {
	tcx.debug_assert_args_compatible(uv.def, uv.args);
	Const::new(tcx, ty::ConstKind::Unevaluated(uv))
	}

	#[inline]
	pub fn new_value(tcx: TyCtxt<'tcx>, valtree: ty::ValTree<'tcx>, ty: Ty<'tcx>) -> Const<'tcx> {
	Const::new(tcx, ty::ConstKind::Value(ty::Value { ty, valtree }))
	}

	#[inline]
	pub fn new_expr(tcx: TyCtxt<'tcx>, expr: ty::Expr<'tcx>) -> Const<'tcx> {
	Const::new(tcx, ty::ConstKind::Expr(expr))
	}

	#[inline]
	pub fn new_error(tcx: TyCtxt<'tcx>, e: ty::ErrorGuaranteed) -> Const<'tcx> {
	Const::new(tcx, ty::ConstKind::Error(e))
	}

	/// Like [Ty::new_error] but for constants.
	#[track_caller]
	pub fn new_misc_error(tcx: TyCtxt<'tcx>) -> Const<'tcx> {
	Const::new_error_with_message(
	tcx,
	DUMMY_SP,
	"ty::ConstKind::Error constructed but no error reported",
	)
	}

	/// Like [Ty::new_error_with_message] but for constants.
	#[track_caller]
	pub fn new_error_with_message<S: Into<MultiSpan>>(
	tcx: TyCtxt<'tcx>,
	span: S,
	msg: impl Into<Cow<'static, str>>,
	) -> Const<'tcx> {
	let reported = tcx.dcx().span_delayed_bug(span, msg);
	Const::new_error(tcx, reported)
	}

	pub fn is_trivially_wf(self) -> bool {
	match self.kind() {
	ty::ConstKind::Param(_) \| ty::ConstKind::Placeholder(_) \| ty::ConstKind::Bound(..) => {
	true
	}
	ty::ConstKind::Infer(_)
	\| ty::ConstKind::Unevaluated(..)
	\| ty::ConstKind::Value(_)
	\| ty::ConstKind::Error(_)
	\| ty::ConstKind::Expr(_) => false,
	}
	}
	}

	impl<'tcx> rustc_type_ir::inherent::Const<TyCtxt<'tcx>> for Const<'tcx> {
	fn new_infer(tcx: TyCtxt<'tcx>, infer: ty::InferConst) -> Self {
	Const::new_infer(tcx, infer)
	}

	fn new_var(tcx: TyCtxt<'tcx>, vid: ty::ConstVid) -> Self {
	Const::new_var(tcx, vid)
	}

	fn new_bound(
	interner: TyCtxt<'tcx>,
	debruijn: ty::DebruijnIndex,
	bound_const: ty::BoundConst,
	) -> Self {
	Const::new_bound(interner, debruijn, bound_const)
	}

	fn new_anon_bound(tcx: TyCtxt<'tcx>, debruijn: ty::DebruijnIndex, var: ty::BoundVar) -> Self {
	Const::new_bound(tcx, debruijn, ty::BoundConst { var })
	}

	fn new_placeholder(tcx: TyCtxt<'tcx>, placeholder: ty::PlaceholderConst) -> Self {
	Const::new_placeholder(tcx, placeholder)
	}

	fn new_unevaluated(interner: TyCtxt<'tcx>, uv: ty::UnevaluatedConst<'tcx>) -> Self {
	Const::new_unevaluated(interner, uv)
	}

	fn new_expr(interner: TyCtxt<'tcx>, expr: ty::Expr<'tcx>) -> Self {
	Const::new_expr(interner, expr)
	}

	fn new_error(interner: TyCtxt<'tcx>, guar: ErrorGuaranteed) -> Self {
	Const::new_error(interner, guar)
	}
	}

	impl<'tcx> Const<'tcx> {
	/// Creates a constant with the given integer value and interns it.
	#[inline]
	pub fn from_bits(
	tcx: TyCtxt<'tcx>,
	bits: u128,
	typing_env: ty::TypingEnv<'tcx>,
	ty: Ty<'tcx>,
	) -> Self {
	let size = tcx
	.layout_of(typing_env.as_query_input(ty))
	.unwrap_or_else(\|e\| panic!("could not compute layout for {ty:?}: {e:?}"))
	.size;
	ty::Const::new_value(
	tcx,
	ty::ValTree::from_scalar_int(tcx, ScalarInt::try_from_uint(bits, size).unwrap()),
	ty,
	)
	}

	#[inline]
	/// Creates an interned zst constant.
	pub fn zero_sized(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Self {
	ty::Const::new_value(tcx, ty::ValTree::zst(tcx), ty)
	}

	#[inline]
	/// Creates an interned bool constant.
	pub fn from_bool(tcx: TyCtxt<'tcx>, v: bool) -> Self {
	Self::from_bits(tcx, v as u128, ty::TypingEnv::fully_monomorphized(), tcx.types.bool)
	}

	#[inline]
	/// Creates an interned usize constant.
	pub fn from_target_usize(tcx: TyCtxt<'tcx>, n: u64) -> Self {
	Self::from_bits(tcx, n as u128, ty::TypingEnv::fully_monomorphized(), tcx.types.usize)
	}

	/// Panics if `self.kind != ty::ConstKind::Value`.
	pub fn to_value(self) -> ty::Value<'tcx> {
	match self.kind() {
	ty::ConstKind::Value(cv) => cv,
	_ => bug!("expected ConstKind::Value, got {:?}", self.kind()),
	}
	}

	/// Attempts to convert to a value.
	///
	/// Note that this does not evaluate the constant.
	pub fn try_to_value(self) -> Option<ty::Value<'tcx>> {
	match self.kind() {
	ty::ConstKind::Value(cv) => Some(cv),
	_ => None,
	}
	}

	/// Convenience method to extract the value of a usize constant,
	/// useful to get the length of an array type.
	///
	/// Note that this does not evaluate the constant.
	#[inline]
	pub fn try_to_target_usize(self, tcx: TyCtxt<'tcx>) -> Option<u64> {
	self.try_to_value()?.try_to_target_usize(tcx)
	}

	pub fn is_ct_infer(self) -> bool {
	matches!(self.kind(), ty::ConstKind::Infer(_))
	}

	/// Iterator that walks `self` and any types reachable from
	/// `self`, in depth-first order. Note that just walks the types
	/// that appear in `self`, it does not descend into the fields of
	/// structs or variants. For example:
	///
	/// ```text
	/// isize => { isize }
	/// Foo<Bar<isize>> => { Foo<Bar<isize>>, Bar<isize>, isize }
	/// [isize] => { [isize], isize }
	/// ```
	pub fn walk(self) -> TypeWalker<TyCtxt<'tcx>> {
	TypeWalker::new(self.into())
	}
	}

	#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable, HashStable)]
	pub enum AnonConstKind {
	/// `feature(generic_const_exprs)` anon consts are allowed to use arbitrary generic parameters in scope
	GCE,
	/// stable `min_const_generics` anon consts are not allowed to use any generic parameters
	MCG,
	/// anon consts used as the length of a repeat expr are syntactically allowed to use generic parameters
	/// but must not depend on the actual instantiation. See #76200 for more information
	RepeatExprCount,
	/// anon consts outside of the type system, e.g. enum discriminants
	NonTypeSystem,
	}