diff --git a/src/librustc_middle/mir/interpret/value.rs b/src/librustc_middle/mir/interpret/value.rs
index 0e913ff58bb4a..ba2a2bd8a026f 100644
--- a/src/librustc_middle/mir/interpret/value.rs
+++ b/src/librustc_middle/mir/interpret/value.rs
@@ -60,6 +60,18 @@ impl<'tcx> ConstValue<'tcx> {
self.try_to_scalar()?.to_bits(size).ok()
}
+ pub fn try_to_bool(&self) -> Option<bool> {
+ match self.try_to_bits(Size::from_bytes(1))? {
+ 0 => Some(false),
+ 1 => Some(true),
+ _ => None,
+ }
+ }
+
+ pub fn try_to_machine_usize(&self, tcx: TyCtxt<'tcx>) -> Option<u64> {
+ Some(self.try_to_bits(tcx.data_layout.pointer_size)? as u64)
+ }
+
pub fn try_to_bits_for_ty(
&self,
tcx: TyCtxt<'tcx>,
diff --git a/src/librustc_middle/ty/consts.rs b/src/librustc_middle/ty/consts.rs
index ced0429deab93..f3a863c3fce62 100644
--- a/src/librustc_middle/ty/consts.rs
+++ b/src/librustc_middle/ty/consts.rs
@@ -1,111 +1,203 @@
-use crate::mir::interpret::truncate;
-use rustc_target::abi::Size;
-
-#[derive(Copy, Clone)]
-/// A type for representing any integer. Only used for printing.
-// FIXME: Use this for the integer-tree representation needed for type level ints and
-// const generics?
-pub struct ConstInt {
- /// Number of bytes of the integer. Only 1, 2, 4, 8, 16 are legal values.
- size: u8,
- /// Whether the value is of a signed integer type.
- signed: bool,
- /// Whether the value is a `usize` or `isize` type.
- is_ptr_sized_integral: bool,
- /// Raw memory of the integer. All bytes beyond the `size` are unused and must be zero.
- raw: u128,
+use crate::mir::interpret::ConstValue;
+use crate::mir::interpret::{LitToConstInput, Scalar};
+use crate::ty::subst::InternalSubsts;
+use crate::ty::{self, Ty, TyCtxt};
+use crate::ty::{ParamEnv, ParamEnvAnd};
+use rustc_errors::ErrorReported;
+use rustc_hir as hir;
+use rustc_hir::def_id::LocalDefId;
+use rustc_macros::HashStable;
+
+mod int;
+mod kind;
+
+pub use int::*;
+pub use kind::*;
+
+/// Typed constant value.
+#[derive(Copy, Clone, Debug, Hash, RustcEncodable, RustcDecodable, Eq, PartialEq, Ord, PartialOrd)]
+#[derive(HashStable)]
+pub struct Const<'tcx> {
+ pub ty: Ty<'tcx>,
+
+ pub val: ConstKind<'tcx>,
}
-impl ConstInt {
- pub fn new(raw: u128, size: Size, signed: bool, is_ptr_sized_integral: bool) -> Self {
- assert!(raw <= truncate(u128::MAX, size));
- Self { raw, size: size.bytes() as u8, signed, is_ptr_sized_integral }
+#[cfg(target_arch = "x86_64")]
+static_assert_size!(Const<'_>, 48);
+
+impl<'tcx> Const<'tcx> {
+ /// Literals and const generic parameters are eagerly converted to a constant, everything else
+ /// becomes `Unevaluated`.
+ pub fn from_anon_const(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> &'tcx Self {
+ Self::from_opt_const_arg_anon_const(tcx, ty::WithOptConstParam::unknown(def_id))
}
-}
-impl std::fmt::Debug for ConstInt {
- fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
- let Self { size, signed, raw, is_ptr_sized_integral } = *self;
- if signed {
- let bit_size = size * 8;
- let min = 1u128 << (bit_size - 1);
- let max = min - 1;
- if raw == min {
- match (size, is_ptr_sized_integral) {
- (_, true) => write!(fmt, "isize::MIN"),
- (1, _) => write!(fmt, "i8::MIN"),
- (2, _) => write!(fmt, "i16::MIN"),
- (4, _) => write!(fmt, "i32::MIN"),
- (8, _) => write!(fmt, "i64::MIN"),
- (16, _) => write!(fmt, "i128::MIN"),
- _ => bug!("ConstInt 0x{:x} with size = {} and signed = {}", raw, size, signed),
- }
- } else if raw == max {
- match (size, is_ptr_sized_integral) {
- (_, true) => write!(fmt, "isize::MAX"),
- (1, _) => write!(fmt, "i8::MAX"),
- (2, _) => write!(fmt, "i16::MAX"),
- (4, _) => write!(fmt, "i32::MAX"),
- (8, _) => write!(fmt, "i64::MAX"),
- (16, _) => write!(fmt, "i128::MAX"),
- _ => bug!("ConstInt 0x{:x} with size = {} and signed = {}", raw, size, signed),
+ pub fn from_opt_const_arg_anon_const(
+ tcx: TyCtxt<'tcx>,
+ def: ty::WithOptConstParam<LocalDefId>,
+ ) -> &'tcx Self {
+ debug!("Const::from_anon_const(def={:?})", def);
+
+ let hir_id = tcx.hir().local_def_id_to_hir_id(def.did);
+
+ let body_id = match tcx.hir().get(hir_id) {
+ hir::Node::AnonConst(ac) => ac.body,
+ _ => span_bug!(
+ tcx.def_span(def.did.to_def_id()),
+ "from_anon_const can only process anonymous constants"
+ ),
+ };
+
+ let expr = &tcx.hir().body(body_id).value;
+
+ let ty = tcx.type_of(def.def_id_for_type_of());
+
+ let lit_input = match expr.kind {
+ hir::ExprKind::Lit(ref lit) => Some(LitToConstInput { lit: &lit.node, ty, neg: false }),
+ hir::ExprKind::Unary(hir::UnOp::UnNeg, ref expr) => match expr.kind {
+ hir::ExprKind::Lit(ref lit) => {
+ Some(LitToConstInput { lit: &lit.node, ty, neg: true })
}
+ _ => None,
+ },
+ _ => None,
+ };
+
+ if let Some(lit_input) = lit_input {
+ // If an error occurred, ignore that it's a literal and leave reporting the error up to
+ // mir.
+ if let Ok(c) = tcx.at(expr.span).lit_to_const(lit_input) {
+ return c;
} else {
- match size {
- 1 => write!(fmt, "{}", raw as i8)?,
- 2 => write!(fmt, "{}", raw as i16)?,
- 4 => write!(fmt, "{}", raw as i32)?,
- 8 => write!(fmt, "{}", raw as i64)?,
- 16 => write!(fmt, "{}", raw as i128)?,
- _ => bug!("ConstInt 0x{:x} with size = {} and signed = {}", raw, size, signed),
- }
- if fmt.alternate() {
- match (size, is_ptr_sized_integral) {
- (_, true) => write!(fmt, "_isize")?,
- (1, _) => write!(fmt, "_i8")?,
- (2, _) => write!(fmt, "_i16")?,
- (4, _) => write!(fmt, "_i32")?,
- (8, _) => write!(fmt, "_i64")?,
- (16, _) => write!(fmt, "_i128")?,
- _ => bug!(),
- }
- }
- Ok(())
+ tcx.sess.delay_span_bug(expr.span, "Const::from_anon_const: couldn't lit_to_const");
}
- } else {
- let max = truncate(u128::MAX, Size::from_bytes(size));
- if raw == max {
- match (size, is_ptr_sized_integral) {
- (_, true) => write!(fmt, "usize::MAX"),
- (1, _) => write!(fmt, "u8::MAX"),
- (2, _) => write!(fmt, "u16::MAX"),
- (4, _) => write!(fmt, "u32::MAX"),
- (8, _) => write!(fmt, "u64::MAX"),
- (16, _) => write!(fmt, "u128::MAX"),
- _ => bug!("ConstInt 0x{:x} with size = {} and signed = {}", raw, size, signed),
- }
- } else {
- match size {
- 1 => write!(fmt, "{}", raw as u8)?,
- 2 => write!(fmt, "{}", raw as u16)?,
- 4 => write!(fmt, "{}", raw as u32)?,
- 8 => write!(fmt, "{}", raw as u64)?,
- 16 => write!(fmt, "{}", raw as u128)?,
- _ => bug!("ConstInt 0x{:x} with size = {} and signed = {}", raw, size, signed),
- }
- if fmt.alternate() {
- match (size, is_ptr_sized_integral) {
- (_, true) => write!(fmt, "_usize")?,
- (1, _) => write!(fmt, "_u8")?,
- (2, _) => write!(fmt, "_u16")?,
- (4, _) => write!(fmt, "_u32")?,
- (8, _) => write!(fmt, "_u64")?,
- (16, _) => write!(fmt, "_u128")?,
- _ => bug!(),
- }
- }
- Ok(())
+ }
+
+ // Unwrap a block, so that e.g. `{ P }` is recognised as a parameter. Const arguments
+ // currently have to be wrapped in curly brackets, so it's necessary to special-case.
+ let expr = match &expr.kind {
+ hir::ExprKind::Block(block, _) if block.stmts.is_empty() && block.expr.is_some() => {
+ block.expr.as_ref().unwrap()
+ }
+ _ => expr,
+ };
+
+ use hir::{def::DefKind::ConstParam, def::Res, ExprKind, Path, QPath};
+ let val = match expr.kind {
+ ExprKind::Path(QPath::Resolved(_, &Path { res: Res::Def(ConstParam, def_id), .. })) => {
+ // Find the name and index of the const parameter by indexing the generics of
+ // the parent item and construct a `ParamConst`.
+ let hir_id = tcx.hir().as_local_hir_id(def_id.expect_local());
+ let item_id = tcx.hir().get_parent_node(hir_id);
+ let item_def_id = tcx.hir().local_def_id(item_id);
+ let generics = tcx.generics_of(item_def_id.to_def_id());
+ let index =
+ generics.param_def_id_to_index[&tcx.hir().local_def_id(hir_id).to_def_id()];
+ let name = tcx.hir().name(hir_id);
+ ty::ConstKind::Param(ty::ParamConst::new(index, name))
}
+ _ => ty::ConstKind::Unevaluated(
+ def.to_global(),
+ InternalSubsts::identity_for_item(tcx, def.did.to_def_id()),
+ None,
+ ),
+ };
+
+ tcx.mk_const(ty::Const { val, ty })
+ }
+
+ #[inline]
+ /// Interns the given value as a constant.
+ pub fn from_value(tcx: TyCtxt<'tcx>, val: ConstValue<'tcx>, ty: Ty<'tcx>) -> &'tcx Self {
+ tcx.mk_const(Self { val: ConstKind::Value(val), ty })
+ }
+
+ #[inline]
+ /// Interns the given scalar as a constant.
+ pub fn from_scalar(tcx: TyCtxt<'tcx>, val: Scalar, ty: Ty<'tcx>) -> &'tcx Self {
+ Self::from_value(tcx, ConstValue::Scalar(val), ty)
+ }
+
+ #[inline]
+ /// Creates a constant with the given integer value and interns it.
+ pub fn from_bits(tcx: TyCtxt<'tcx>, bits: u128, ty: ParamEnvAnd<'tcx, Ty<'tcx>>) -> &'tcx Self {
+ let size = tcx
+ .layout_of(ty)
+ .unwrap_or_else(|e| panic!("could not compute layout for {:?}: {:?}", ty, e))
+ .size;
+ Self::from_scalar(tcx, Scalar::from_uint(bits, size), ty.value)
+ }
+
+ #[inline]
+ /// Creates an interned zst constant.
+ pub fn zero_sized(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> &'tcx Self {
+ Self::from_scalar(tcx, Scalar::zst(), ty)
+ }
+
+ #[inline]
+ /// Creates an interned bool constant.
+ pub fn from_bool(tcx: TyCtxt<'tcx>, v: bool) -> &'tcx Self {
+ Self::from_bits(tcx, v as u128, ParamEnv::empty().and(tcx.types.bool))
+ }
+
+ #[inline]
+ /// Creates an interned usize constant.
+ pub fn from_usize(tcx: TyCtxt<'tcx>, n: u64) -> &'tcx Self {
+ Self::from_bits(tcx, n as u128, ParamEnv::empty().and(tcx.types.usize))
+ }
+
+ #[inline]
+ /// Attempts to evaluate the given constant to bits. Can fail to evaluate in the presence of
+ /// generics (or erroneous code) or if the value can't be represented as bits (e.g. because it
+ /// contains const generic parameters or pointers).
+ pub fn try_eval_bits(
+ &self,
+ tcx: TyCtxt<'tcx>,
+ param_env: ParamEnv<'tcx>,
+ ty: Ty<'tcx>,
+ ) -> Option<u128> {
+ assert_eq!(self.ty, ty);
+ let size = tcx.layout_of(param_env.with_reveal_all().and(ty)).ok()?.size;
+ // if `ty` does not depend on generic parameters, use an empty param_env
+ self.val.eval(tcx, param_env).try_to_bits(size)
+ }
+
+ #[inline]
+ pub fn try_eval_bool(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Option<bool> {
+ self.val.eval(tcx, param_env).try_to_bool()
+ }
+
+ #[inline]
+ pub fn try_eval_usize(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Option<u64> {
+ self.val.eval(tcx, param_env).try_to_machine_usize(tcx)
+ }
+
+ #[inline]
+ /// Tries to evaluate the constant if it is `Unevaluated`. If that doesn't succeed, return the
+ /// unevaluated constant.
+ pub fn eval(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> &Const<'tcx> {
+ if let Some(val) = self.val.try_eval(tcx, param_env) {
+ match val {
+ Ok(val) => Const::from_value(tcx, val, self.ty),
+ Err(ErrorReported) => tcx.const_error(self.ty),
+ }
+ } else {
+ self
}
}
+
+ #[inline]
+ /// Panics if the value cannot be evaluated or doesn't contain a valid integer of the given type.
+ pub fn eval_bits(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, ty: Ty<'tcx>) -> u128 {
+ self.try_eval_bits(tcx, param_env, ty)
+ .unwrap_or_else(|| bug!("expected bits of {:#?}, got {:#?}", ty, self))
+ }
+
+ #[inline]
+ /// Panics if the value cannot be evaluated or doesn't contain a valid `usize`.
+ pub fn eval_usize(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> u64 {
+ self.try_eval_usize(tcx, param_env)
+ .unwrap_or_else(|| bug!("expected usize, got {:#?}", self))
+ }
}
diff --git a/src/librustc_middle/ty/consts/int.rs b/src/librustc_middle/ty/consts/int.rs
new file mode 100644
index 0000000000000..ced0429deab93
--- /dev/null
+++ b/src/librustc_middle/ty/consts/int.rs
@@ -0,0 +1,111 @@
+use crate::mir::interpret::truncate;
+use rustc_target::abi::Size;
+
+#[derive(Copy, Clone)]
+/// A type for representing any integer. Only used for printing.
+// FIXME: Use this for the integer-tree representation needed for type level ints and
+// const generics?
+pub struct ConstInt {
+ /// Number of bytes of the integer. Only 1, 2, 4, 8, 16 are legal values.
+ size: u8,
+ /// Whether the value is of a signed integer type.
+ signed: bool,
+ /// Whether the value is a `usize` or `isize` type.
+ is_ptr_sized_integral: bool,
+ /// Raw memory of the integer. All bytes beyond the `size` are unused and must be zero.
+ raw: u128,
+}
+
+impl ConstInt {
+ pub fn new(raw: u128, size: Size, signed: bool, is_ptr_sized_integral: bool) -> Self {
+ assert!(raw <= truncate(u128::MAX, size));
+ Self { raw, size: size.bytes() as u8, signed, is_ptr_sized_integral }
+ }
+}
+
+impl std::fmt::Debug for ConstInt {
+ fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+ let Self { size, signed, raw, is_ptr_sized_integral } = *self;
+ if signed {
+ let bit_size = size * 8;
+ let min = 1u128 << (bit_size - 1);
+ let max = min - 1;
+ if raw == min {
+ match (size, is_ptr_sized_integral) {
+ (_, true) => write!(fmt, "isize::MIN"),
+ (1, _) => write!(fmt, "i8::MIN"),
+ (2, _) => write!(fmt, "i16::MIN"),
+ (4, _) => write!(fmt, "i32::MIN"),
+ (8, _) => write!(fmt, "i64::MIN"),
+ (16, _) => write!(fmt, "i128::MIN"),
+ _ => bug!("ConstInt 0x{:x} with size = {} and signed = {}", raw, size, signed),
+ }
+ } else if raw == max {
+ match (size, is_ptr_sized_integral) {
+ (_, true) => write!(fmt, "isize::MAX"),
+ (1, _) => write!(fmt, "i8::MAX"),
+ (2, _) => write!(fmt, "i16::MAX"),
+ (4, _) => write!(fmt, "i32::MAX"),
+ (8, _) => write!(fmt, "i64::MAX"),
+ (16, _) => write!(fmt, "i128::MAX"),
+ _ => bug!("ConstInt 0x{:x} with size = {} and signed = {}", raw, size, signed),
+ }
+ } else {
+ match size {
+ 1 => write!(fmt, "{}", raw as i8)?,
+ 2 => write!(fmt, "{}", raw as i16)?,
+ 4 => write!(fmt, "{}", raw as i32)?,
+ 8 => write!(fmt, "{}", raw as i64)?,
+ 16 => write!(fmt, "{}", raw as i128)?,
+ _ => bug!("ConstInt 0x{:x} with size = {} and signed = {}", raw, size, signed),
+ }
+ if fmt.alternate() {
+ match (size, is_ptr_sized_integral) {
+ (_, true) => write!(fmt, "_isize")?,
+ (1, _) => write!(fmt, "_i8")?,
+ (2, _) => write!(fmt, "_i16")?,
+ (4, _) => write!(fmt, "_i32")?,
+ (8, _) => write!(fmt, "_i64")?,
+ (16, _) => write!(fmt, "_i128")?,
+ _ => bug!(),
+ }
+ }
+ Ok(())
+ }
+ } else {
+ let max = truncate(u128::MAX, Size::from_bytes(size));
+ if raw == max {
+ match (size, is_ptr_sized_integral) {
+ (_, true) => write!(fmt, "usize::MAX"),
+ (1, _) => write!(fmt, "u8::MAX"),
+ (2, _) => write!(fmt, "u16::MAX"),
+ (4, _) => write!(fmt, "u32::MAX"),
+ (8, _) => write!(fmt, "u64::MAX"),
+ (16, _) => write!(fmt, "u128::MAX"),
+ _ => bug!("ConstInt 0x{:x} with size = {} and signed = {}", raw, size, signed),
+ }
+ } else {
+ match size {
+ 1 => write!(fmt, "{}", raw as u8)?,
+ 2 => write!(fmt, "{}", raw as u16)?,
+ 4 => write!(fmt, "{}", raw as u32)?,
+ 8 => write!(fmt, "{}", raw as u64)?,
+ 16 => write!(fmt, "{}", raw as u128)?,
+ _ => bug!("ConstInt 0x{:x} with size = {} and signed = {}", raw, size, signed),
+ }
+ if fmt.alternate() {
+ match (size, is_ptr_sized_integral) {
+ (_, true) => write!(fmt, "_usize")?,
+ (1, _) => write!(fmt, "_u8")?,
+ (2, _) => write!(fmt, "_u16")?,
+ (4, _) => write!(fmt, "_u32")?,
+ (8, _) => write!(fmt, "_u64")?,
+ (16, _) => write!(fmt, "_u128")?,
+ _ => bug!(),
+ }
+ }
+ Ok(())
+ }
+ }
+ }
+}
diff --git a/src/librustc_middle/ty/consts/kind.rs b/src/librustc_middle/ty/consts/kind.rs
new file mode 100644
index 0000000000000..75287ff7dace3
--- /dev/null
+++ b/src/librustc_middle/ty/consts/kind.rs
@@ -0,0 +1,135 @@
+use crate::mir::interpret::ConstValue;
+use crate::mir::interpret::Scalar;
+use crate::mir::Promoted;
+use crate::ty::subst::{InternalSubsts, SubstsRef};
+use crate::ty::ParamEnv;
+use crate::ty::{self, TyCtxt, TypeFoldable};
+use rustc_errors::ErrorReported;
+use rustc_hir::def_id::DefId;
+use rustc_macros::HashStable;
+use rustc_target::abi::Size;
+
+/// Represents a constant in Rust.
+#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, RustcEncodable, RustcDecodable, Hash)]
+#[derive(HashStable)]
+pub enum ConstKind<'tcx> {
+ /// A const generic parameter.
+ Param(ty::ParamConst),
+
+ /// Infer the value of the const.
+ Infer(InferConst<'tcx>),
+
+ /// Bound const variable, used only when preparing a trait query.
+ Bound(ty::DebruijnIndex, ty::BoundVar),
+
+ /// A placeholder const - universally quantified higher-ranked const.
+ Placeholder(ty::PlaceholderConst),
+
+ /// Used in the HIR by using `Unevaluated` everywhere and later normalizing to one of the other
+ /// variants when the code is monomorphic enough for that.
+ Unevaluated(ty::WithOptConstParam<DefId>, SubstsRef<'tcx>, Option<Promoted>),
+
+ /// Used to hold computed value.
+ Value(ConstValue<'tcx>),
+
+ /// A placeholder for a const which could not be computed; this is
+ /// propagated to avoid useless error messages.
+ Error(ty::sty::DelaySpanBugEmitted),
+}
+
+#[cfg(target_arch = "x86_64")]
+static_assert_size!(ConstKind<'_>, 40);
+
+impl<'tcx> ConstKind<'tcx> {
+ #[inline]
+ pub fn try_to_value(self) -> Option<ConstValue<'tcx>> {
+ if let ConstKind::Value(val) = self { Some(val) } else { None }
+ }
+
+ #[inline]
+ pub fn try_to_scalar(self) -> Option<Scalar> {
+ self.try_to_value()?.try_to_scalar()
+ }
+
+ #[inline]
+ pub fn try_to_bits(self, size: Size) -> Option<u128> {
+ self.try_to_value()?.try_to_bits(size)
+ }
+
+ #[inline]
+ pub fn try_to_bool(self) -> Option<bool> {
+ self.try_to_value()?.try_to_bool()
+ }
+
+ #[inline]
+ pub fn try_to_machine_usize(self, tcx: TyCtxt<'tcx>) -> Option<u64> {
+ self.try_to_value()?.try_to_machine_usize(tcx)
+ }
+}
+
+/// An inference variable for a const, for use in const generics.
+#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, RustcEncodable, RustcDecodable, Hash)]
+#[derive(HashStable)]
+pub enum InferConst<'tcx> {
+ /// Infer the value of the const.
+ Var(ty::ConstVid<'tcx>),
+ /// A fresh const variable. See `infer::freshen` for more details.
+ Fresh(u32),
+}
+
+impl<'tcx> ConstKind<'tcx> {
+ #[inline]
+ /// Tries to evaluate the constant if it is `Unevaluated`. If that doesn't succeed, return the
+ /// unevaluated constant.
+ pub fn eval(self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Self {
+ self.try_eval(tcx, param_env).and_then(Result::ok).map(ConstKind::Value).unwrap_or(self)
+ }
+
+ #[inline]
+ /// Tries to evaluate the constant if it is `Unevaluated`. If that isn't possible or necessary
+ /// return `None`.
+ pub(super) fn try_eval(
+ self,
+ tcx: TyCtxt<'tcx>,
+ param_env: ParamEnv<'tcx>,
+ ) -> Option<Result<ConstValue<'tcx>, ErrorReported>> {
+ if let ConstKind::Unevaluated(def, substs, promoted) = self {
+ use crate::mir::interpret::ErrorHandled;
+
+ let param_env_and_substs = param_env.with_reveal_all().and(substs);
+
+ // HACK(eddyb) this erases lifetimes even though `const_eval_resolve`
+ // also does later, but we want to do it before checking for
+ // inference variables.
+ let param_env_and_substs = tcx.erase_regions(¶m_env_and_substs);
+
+ // HACK(eddyb) when the query key would contain inference variables,
+ // attempt using identity substs and `ParamEnv` instead, that will succeed
+ // when the expression doesn't depend on any parameters.
+ // FIXME(eddyb, skinny121) pass `InferCtxt` into here when it's available, so that
+ // we can call `infcx.const_eval_resolve` which handles inference variables.
+ let param_env_and_substs = if param_env_and_substs.needs_infer() {
+ tcx.param_env(def.did).and(InternalSubsts::identity_for_item(tcx, def.did))
+ } else {
+ param_env_and_substs
+ };
+
+ // FIXME(eddyb) maybe the `const_eval_*` methods should take
+ // `ty::ParamEnvAnd<SubstsRef>` instead of having them separate.
+ let (param_env, substs) = param_env_and_substs.into_parts();
+ // try to resolve e.g. associated constants to their definition on an impl, and then
+ // evaluate the const.
+ match tcx.const_eval_resolve(param_env, def, substs, promoted, None) {
+ // NOTE(eddyb) `val` contains no lifetimes/types/consts,
+ // and we use the original type, so nothing from `substs`
+ // (which may be identity substs, see above),
+ // can leak through `val` into the const we return.
+ Ok(val) => Some(Ok(val)),
+ Err(ErrorHandled::TooGeneric | ErrorHandled::Linted) => None,
+ Err(ErrorHandled::Reported(e)) => Some(Err(e)),
+ }
+ } else {
+ None
+ }
+ }
+}
diff --git a/src/librustc_middle/ty/mod.rs b/src/librustc_middle/ty/mod.rs
index fe2a60401b4a6..b3cfcc0f4c2a8 100644
--- a/src/librustc_middle/ty/mod.rs
+++ b/src/librustc_middle/ty/mod.rs
@@ -60,9 +60,9 @@ pub use self::sty::{Binder, BoundTy, BoundTyKind, BoundVar, DebruijnIndex, INNER
pub use self::sty::{BoundRegion, EarlyBoundRegion, FreeRegion, Region};
pub use self::sty::{CanonicalPolyFnSig, FnSig, GenSig, PolyFnSig, PolyGenSig};
pub use self::sty::{ClosureSubsts, GeneratorSubsts, TypeAndMut, UpvarSubsts};
-pub use self::sty::{Const, ConstKind, ExistentialProjection, PolyExistentialProjection};
pub use self::sty::{ConstVid, FloatVid, IntVid, RegionVid, TyVid};
-pub use self::sty::{ExistentialPredicate, InferConst, InferTy, ParamConst, ParamTy, ProjectionTy};
+pub use self::sty::{ExistentialPredicate, InferTy, ParamConst, ParamTy, ProjectionTy};
+pub use self::sty::{ExistentialProjection, PolyExistentialProjection};
pub use self::sty::{ExistentialTraitRef, PolyExistentialTraitRef};
pub use self::sty::{PolyTraitRef, TraitRef, TyKind};
pub use crate::ty::diagnostics::*;
@@ -87,7 +87,7 @@ pub use self::trait_def::TraitDef;
pub use self::query::queries;
-pub use self::consts::ConstInt;
+pub use self::consts::{Const, ConstInt, ConstKind, InferConst};
pub mod adjustment;
pub mod binding;
diff --git a/src/librustc_middle/ty/sty.rs b/src/librustc_middle/ty/sty.rs
index 3104d2ee36a79..2f17db6223362 100644
--- a/src/librustc_middle/ty/sty.rs
+++ b/src/librustc_middle/ty/sty.rs
@@ -6,24 +6,20 @@ use self::InferTy::*;
use self::TyKind::*;
use crate::infer::canonical::Canonical;
-use crate::mir::interpret::ConstValue;
-use crate::mir::interpret::{LitToConstInput, Scalar};
-use crate::mir::Promoted;
use crate::ty::subst::{GenericArg, InternalSubsts, Subst, SubstsRef};
use crate::ty::{
self, AdtDef, DefIdTree, Discr, Ty, TyCtxt, TypeFlags, TypeFoldable, WithConstness,
};
-use crate::ty::{List, ParamEnv, ParamEnvAnd, TyS};
+use crate::ty::{List, ParamEnv, TyS};
use polonius_engine::Atom;
use rustc_ast::ast;
use rustc_data_structures::captures::Captures;
-use rustc_errors::ErrorReported;
use rustc_hir as hir;
-use rustc_hir::def_id::{DefId, LocalDefId};
+use rustc_hir::def_id::DefId;
use rustc_index::vec::Idx;
use rustc_macros::HashStable;
use rustc_span::symbol::{kw, Ident, Symbol};
-use rustc_target::abi::{Size, VariantIdx};
+use rustc_target::abi::VariantIdx;
use rustc_target::spec::abi;
use std::borrow::Cow;
use std::cmp::Ordering;
@@ -1122,7 +1118,7 @@ impl<'tcx> ParamConst {
ParamConst::new(def.index, def.name)
}
- pub fn to_const(self, tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> &'tcx Const<'tcx> {
+ pub fn to_const(self, tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> &'tcx ty::Const<'tcx> {
tcx.mk_const_param(self.index, self.name, ty)
}
}
@@ -2193,277 +2189,3 @@ impl<'tcx> TyS<'tcx> {
tcx.layout_of(tcx.param_env(did).and(self)).map(|layout| layout.is_zst()).unwrap_or(false)
}
}
-
-/// Typed constant value.
-#[derive(Copy, Clone, Debug, Hash, RustcEncodable, RustcDecodable, Eq, PartialEq, Ord, PartialOrd)]
-#[derive(HashStable)]
-pub struct Const<'tcx> {
- pub ty: Ty<'tcx>,
-
- pub val: ConstKind<'tcx>,
-}
-
-#[cfg(target_arch = "x86_64")]
-static_assert_size!(Const<'_>, 48);
-
-impl<'tcx> Const<'tcx> {
- /// Literals and const generic parameters are eagerly converted to a constant, everything else
- /// becomes `Unevaluated`.
- pub fn from_anon_const(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> &'tcx Self {
- Self::from_opt_const_arg_anon_const(tcx, ty::WithOptConstParam::unknown(def_id))
- }
-
- pub fn from_opt_const_arg_anon_const(
- tcx: TyCtxt<'tcx>,
- def: ty::WithOptConstParam<LocalDefId>,
- ) -> &'tcx Self {
- debug!("Const::from_anon_const(def={:?})", def);
-
- let hir_id = tcx.hir().local_def_id_to_hir_id(def.did);
-
- let body_id = match tcx.hir().get(hir_id) {
- hir::Node::AnonConst(ac) => ac.body,
- _ => span_bug!(
- tcx.def_span(def.did.to_def_id()),
- "from_anon_const can only process anonymous constants"
- ),
- };
-
- let expr = &tcx.hir().body(body_id).value;
-
- let ty = tcx.type_of(def.def_id_for_type_of());
-
- let lit_input = match expr.kind {
- hir::ExprKind::Lit(ref lit) => Some(LitToConstInput { lit: &lit.node, ty, neg: false }),
- hir::ExprKind::Unary(hir::UnOp::UnNeg, ref expr) => match expr.kind {
- hir::ExprKind::Lit(ref lit) => {
- Some(LitToConstInput { lit: &lit.node, ty, neg: true })
- }
- _ => None,
- },
- _ => None,
- };
-
- if let Some(lit_input) = lit_input {
- // If an error occurred, ignore that it's a literal and leave reporting the error up to
- // mir.
- if let Ok(c) = tcx.at(expr.span).lit_to_const(lit_input) {
- return c;
- } else {
- tcx.sess.delay_span_bug(expr.span, "Const::from_anon_const: couldn't lit_to_const");
- }
- }
-
- // Unwrap a block, so that e.g. `{ P }` is recognised as a parameter. Const arguments
- // currently have to be wrapped in curly brackets, so it's necessary to special-case.
- let expr = match &expr.kind {
- hir::ExprKind::Block(block, _) if block.stmts.is_empty() && block.expr.is_some() => {
- block.expr.as_ref().unwrap()
- }
- _ => expr,
- };
-
- use hir::{def::DefKind::ConstParam, def::Res, ExprKind, Path, QPath};
- let val = match expr.kind {
- ExprKind::Path(QPath::Resolved(_, &Path { res: Res::Def(ConstParam, def_id), .. })) => {
- // Find the name and index of the const parameter by indexing the generics of
- // the parent item and construct a `ParamConst`.
- let hir_id = tcx.hir().as_local_hir_id(def_id.expect_local());
- let item_id = tcx.hir().get_parent_node(hir_id);
- let item_def_id = tcx.hir().local_def_id(item_id);
- let generics = tcx.generics_of(item_def_id.to_def_id());
- let index =
- generics.param_def_id_to_index[&tcx.hir().local_def_id(hir_id).to_def_id()];
- let name = tcx.hir().name(hir_id);
- ty::ConstKind::Param(ty::ParamConst::new(index, name))
- }
- _ => ty::ConstKind::Unevaluated(
- def.to_global(),
- InternalSubsts::identity_for_item(tcx, def.did.to_def_id()),
- None,
- ),
- };
-
- tcx.mk_const(ty::Const { val, ty })
- }
-
- #[inline]
- /// Interns the given value as a constant.
- pub fn from_value(tcx: TyCtxt<'tcx>, val: ConstValue<'tcx>, ty: Ty<'tcx>) -> &'tcx Self {
- tcx.mk_const(Self { val: ConstKind::Value(val), ty })
- }
-
- #[inline]
- /// Interns the given scalar as a constant.
- pub fn from_scalar(tcx: TyCtxt<'tcx>, val: Scalar, ty: Ty<'tcx>) -> &'tcx Self {
- Self::from_value(tcx, ConstValue::Scalar(val), ty)
- }
-
- #[inline]
- /// Creates a constant with the given integer value and interns it.
- pub fn from_bits(tcx: TyCtxt<'tcx>, bits: u128, ty: ParamEnvAnd<'tcx, Ty<'tcx>>) -> &'tcx Self {
- let size = tcx
- .layout_of(ty)
- .unwrap_or_else(|e| panic!("could not compute layout for {:?}: {:?}", ty, e))
- .size;
- Self::from_scalar(tcx, Scalar::from_uint(bits, size), ty.value)
- }
-
- #[inline]
- /// Creates an interned zst constant.
- pub fn zero_sized(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> &'tcx Self {
- Self::from_scalar(tcx, Scalar::zst(), ty)
- }
-
- #[inline]
- /// Creates an interned bool constant.
- pub fn from_bool(tcx: TyCtxt<'tcx>, v: bool) -> &'tcx Self {
- Self::from_bits(tcx, v as u128, ParamEnv::empty().and(tcx.types.bool))
- }
-
- #[inline]
- /// Creates an interned usize constant.
- pub fn from_usize(tcx: TyCtxt<'tcx>, n: u64) -> &'tcx Self {
- Self::from_bits(tcx, n as u128, ParamEnv::empty().and(tcx.types.usize))
- }
-
- #[inline]
- /// Attempts to evaluate the given constant to bits. Can fail to evaluate in the presence of
- /// generics (or erroneous code) or if the value can't be represented as bits (e.g. because it
- /// contains const generic parameters or pointers).
- pub fn try_eval_bits(
- &self,
- tcx: TyCtxt<'tcx>,
- param_env: ParamEnv<'tcx>,
- ty: Ty<'tcx>,
- ) -> Option<u128> {
- assert_eq!(self.ty, ty);
- let size = tcx.layout_of(param_env.with_reveal_all().and(ty)).ok()?.size;
- // if `ty` does not depend on generic parameters, use an empty param_env
- self.eval(tcx, param_env).val.try_to_bits(size)
- }
-
- #[inline]
- /// Tries to evaluate the constant if it is `Unevaluated`. If that doesn't succeed, return the
- /// unevaluated constant.
- pub fn eval(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> &Const<'tcx> {
- if let ConstKind::Unevaluated(def, substs, promoted) = self.val {
- use crate::mir::interpret::ErrorHandled;
-
- let param_env_and_substs = param_env.with_reveal_all().and(substs);
-
- // HACK(eddyb) this erases lifetimes even though `const_eval_resolve`
- // also does later, but we want to do it before checking for
- // inference variables.
- let param_env_and_substs = tcx.erase_regions(¶m_env_and_substs);
-
- // HACK(eddyb) when the query key would contain inference variables,
- // attempt using identity substs and `ParamEnv` instead, that will succeed
- // when the expression doesn't depend on any parameters.
- // FIXME(eddyb, skinny121) pass `InferCtxt` into here when it's available, so that
- // we can call `infcx.const_eval_resolve` which handles inference variables.
- let param_env_and_substs = if param_env_and_substs.needs_infer() {
- tcx.param_env(def.did).and(InternalSubsts::identity_for_item(tcx, def.did))
- } else {
- param_env_and_substs
- };
-
- // FIXME(eddyb) maybe the `const_eval_*` methods should take
- // `ty::ParamEnvAnd<SubstsRef>` instead of having them separate.
- let (param_env, substs) = param_env_and_substs.into_parts();
- // try to resolve e.g. associated constants to their definition on an impl, and then
- // evaluate the const.
- match tcx.const_eval_resolve(param_env, def, substs, promoted, None) {
- // NOTE(eddyb) `val` contains no lifetimes/types/consts,
- // and we use the original type, so nothing from `substs`
- // (which may be identity substs, see above),
- // can leak through `val` into the const we return.
- Ok(val) => Const::from_value(tcx, val, self.ty),
- Err(ErrorHandled::TooGeneric | ErrorHandled::Linted) => self,
- Err(ErrorHandled::Reported(ErrorReported)) => tcx.const_error(self.ty),
- }
- } else {
- self
- }
- }
-
- #[inline]
- pub fn try_eval_bool(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Option<bool> {
- self.try_eval_bits(tcx, param_env, tcx.types.bool).and_then(|v| match v {
- 0 => Some(false),
- 1 => Some(true),
- _ => None,
- })
- }
-
- #[inline]
- pub fn try_eval_usize(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Option<u64> {
- self.try_eval_bits(tcx, param_env, tcx.types.usize).map(|v| v as u64)
- }
-
- #[inline]
- /// Panics if the value cannot be evaluated or doesn't contain a valid integer of the given type.
- pub fn eval_bits(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, ty: Ty<'tcx>) -> u128 {
- self.try_eval_bits(tcx, param_env, ty)
- .unwrap_or_else(|| bug!("expected bits of {:#?}, got {:#?}", ty, self))
- }
-
- #[inline]
- /// Panics if the value cannot be evaluated or doesn't contain a valid `usize`.
- pub fn eval_usize(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> u64 {
- self.eval_bits(tcx, param_env, tcx.types.usize) as u64
- }
-}
-
-/// Represents a constant in Rust.
-#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, RustcEncodable, RustcDecodable, Hash)]
-#[derive(HashStable)]
-pub enum ConstKind<'tcx> {
- /// A const generic parameter.
- Param(ParamConst),
-
- /// Infer the value of the const.
- Infer(InferConst<'tcx>),
-
- /// Bound const variable, used only when preparing a trait query.
- Bound(DebruijnIndex, BoundVar),
-
- /// A placeholder const - universally quantified higher-ranked const.
- Placeholder(ty::PlaceholderConst),
-
- /// Used in the HIR by using `Unevaluated` everywhere and later normalizing to one of the other
- /// variants when the code is monomorphic enough for that.
- Unevaluated(ty::WithOptConstParam<DefId>, SubstsRef<'tcx>, Option<Promoted>),
-
- /// Used to hold computed value.
- Value(ConstValue<'tcx>),
-
- /// A placeholder for a const which could not be computed; this is
- /// propagated to avoid useless error messages.
- Error(DelaySpanBugEmitted),
-}
-
-#[cfg(target_arch = "x86_64")]
-static_assert_size!(ConstKind<'_>, 40);
-
-impl<'tcx> ConstKind<'tcx> {
- #[inline]
- pub fn try_to_scalar(&self) -> Option<Scalar> {
- if let ConstKind::Value(val) = self { val.try_to_scalar() } else { None }
- }
-
- #[inline]
- pub fn try_to_bits(&self, size: Size) -> Option<u128> {
- if let ConstKind::Value(val) = self { val.try_to_bits(size) } else { None }
- }
-}
-
-/// An inference variable for a const, for use in const generics.
-#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, RustcEncodable, RustcDecodable, Hash)]
-#[derive(HashStable)]
-pub enum InferConst<'tcx> {
- /// Infer the value of the const.
- Var(ConstVid<'tcx>),
- /// A fresh const variable. See `infer::freshen` for more details.
- Fresh(u32),
-}