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Move ty::Const and ty::ConstKind into their own modules

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This commit is contained in:
Oliver Scherer 2020-07-11 09:49:22 +02:00
parent 5c0e172f91
commit 763aaef670
5 changed files with 445 additions and 426 deletions
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292
src/librustc_middle/ty/consts.rs
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@ -1,111 +1,203 @@
use crate::mir::interpret::truncate;
use rustc_target::abi::Size;
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;
#[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,
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(())
}
} 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(())
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.val.eval(tcx, param_env).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 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]
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]
/// 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))
}
}

111
src/librustc_middle/ty/consts/int.rs Normal file
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@ -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(())
}
}
}
}

135
src/librustc_middle/ty/consts/kind.rs Normal file
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@ -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 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(&param_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
}
}
}

6
src/librustc_middle/ty/mod.rs
View File

@ -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;

327
src/librustc_middle/ty/sty.rs
View File

@ -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)
}
}
@ -2193,318 +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.val.eval(tcx, param_env).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 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
}
}
}
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 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(&param_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
}
}
}
impl<'tcx> Const<'tcx> {
#[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]
/// 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))
}
}
/// 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_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(ConstVid<'tcx>),
/// A fresh const variable. See `infer::freshen` for more details.
Fresh(u32),
}