af7d3e501b
I found these by commenting out all `Lift` derives and then adding back the ones that were necessary to successfully compile.
1063 lines
36 KiB
Rust
1063 lines
36 KiB
Rust
// Generic arguments.
|
|
|
|
use crate::ty::codec::{TyDecoder, TyEncoder};
|
|
use crate::ty::fold::{FallibleTypeFolder, TypeFoldable, TypeFolder, TypeSuperFoldable};
|
|
use crate::ty::sty::{ClosureArgs, GeneratorArgs, InlineConstArgs};
|
|
use crate::ty::visit::{TypeVisitable, TypeVisitableExt, TypeVisitor};
|
|
use crate::ty::{self, Lift, List, ParamConst, Ty, TyCtxt};
|
|
|
|
use rustc_data_structures::intern::Interned;
|
|
use rustc_errors::{DiagnosticArgValue, IntoDiagnosticArg};
|
|
use rustc_hir::def_id::DefId;
|
|
use rustc_macros::HashStable;
|
|
use rustc_serialize::{self, Decodable, Encodable};
|
|
use rustc_span::sym;
|
|
use rustc_type_ir::WithCachedTypeInfo;
|
|
use smallvec::SmallVec;
|
|
|
|
use core::intrinsics;
|
|
use std::cmp::Ordering;
|
|
use std::marker::PhantomData;
|
|
use std::mem;
|
|
use std::num::NonZeroUsize;
|
|
use std::ops::{ControlFlow, Deref};
|
|
|
|
/// An entity in the Rust type system, which can be one of
|
|
/// several kinds (types, lifetimes, and consts).
|
|
/// To reduce memory usage, a `GenericArg` is an interned pointer,
|
|
/// with the lowest 2 bits being reserved for a tag to
|
|
/// indicate the type (`Ty`, `Region`, or `Const`) it points to.
|
|
///
|
|
/// Note: the `PartialEq`, `Eq` and `Hash` derives are only valid because `Ty`,
|
|
/// `Region` and `Const` are all interned.
|
|
#[derive(Copy, Clone, PartialEq, Eq, Hash)]
|
|
pub struct GenericArg<'tcx> {
|
|
ptr: NonZeroUsize,
|
|
marker: PhantomData<(Ty<'tcx>, ty::Region<'tcx>, ty::Const<'tcx>)>,
|
|
}
|
|
|
|
impl<'tcx> IntoDiagnosticArg for GenericArg<'tcx> {
|
|
fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
|
|
self.to_string().into_diagnostic_arg()
|
|
}
|
|
}
|
|
|
|
const TAG_MASK: usize = 0b11;
|
|
const TYPE_TAG: usize = 0b00;
|
|
const REGION_TAG: usize = 0b01;
|
|
const CONST_TAG: usize = 0b10;
|
|
|
|
#[derive(Debug, TyEncodable, TyDecodable, PartialEq, Eq, PartialOrd, Ord, HashStable)]
|
|
pub enum GenericArgKind<'tcx> {
|
|
Lifetime(ty::Region<'tcx>),
|
|
Type(Ty<'tcx>),
|
|
Const(ty::Const<'tcx>),
|
|
}
|
|
|
|
impl<'tcx> GenericArgKind<'tcx> {
|
|
#[inline]
|
|
fn pack(self) -> GenericArg<'tcx> {
|
|
let (tag, ptr) = match self {
|
|
GenericArgKind::Lifetime(lt) => {
|
|
// Ensure we can use the tag bits.
|
|
assert_eq!(mem::align_of_val(&*lt.0.0) & TAG_MASK, 0);
|
|
(REGION_TAG, lt.0.0 as *const ty::RegionKind<'tcx> as usize)
|
|
}
|
|
GenericArgKind::Type(ty) => {
|
|
// Ensure we can use the tag bits.
|
|
assert_eq!(mem::align_of_val(&*ty.0.0) & TAG_MASK, 0);
|
|
(TYPE_TAG, ty.0.0 as *const WithCachedTypeInfo<ty::TyKind<'tcx>> as usize)
|
|
}
|
|
GenericArgKind::Const(ct) => {
|
|
// Ensure we can use the tag bits.
|
|
assert_eq!(mem::align_of_val(&*ct.0.0) & TAG_MASK, 0);
|
|
(CONST_TAG, ct.0.0 as *const ty::ConstData<'tcx> as usize)
|
|
}
|
|
};
|
|
|
|
GenericArg { ptr: unsafe { NonZeroUsize::new_unchecked(ptr | tag) }, marker: PhantomData }
|
|
}
|
|
}
|
|
|
|
impl<'tcx> Ord for GenericArg<'tcx> {
|
|
fn cmp(&self, other: &GenericArg<'tcx>) -> Ordering {
|
|
self.unpack().cmp(&other.unpack())
|
|
}
|
|
}
|
|
|
|
impl<'tcx> PartialOrd for GenericArg<'tcx> {
|
|
fn partial_cmp(&self, other: &GenericArg<'tcx>) -> Option<Ordering> {
|
|
Some(self.cmp(&other))
|
|
}
|
|
}
|
|
|
|
impl<'tcx> From<ty::Region<'tcx>> for GenericArg<'tcx> {
|
|
#[inline]
|
|
fn from(r: ty::Region<'tcx>) -> GenericArg<'tcx> {
|
|
GenericArgKind::Lifetime(r).pack()
|
|
}
|
|
}
|
|
|
|
impl<'tcx> From<Ty<'tcx>> for GenericArg<'tcx> {
|
|
#[inline]
|
|
fn from(ty: Ty<'tcx>) -> GenericArg<'tcx> {
|
|
GenericArgKind::Type(ty).pack()
|
|
}
|
|
}
|
|
|
|
impl<'tcx> From<ty::Const<'tcx>> for GenericArg<'tcx> {
|
|
#[inline]
|
|
fn from(c: ty::Const<'tcx>) -> GenericArg<'tcx> {
|
|
GenericArgKind::Const(c).pack()
|
|
}
|
|
}
|
|
|
|
impl<'tcx> From<ty::Term<'tcx>> for GenericArg<'tcx> {
|
|
fn from(value: ty::Term<'tcx>) -> Self {
|
|
match value.unpack() {
|
|
ty::TermKind::Ty(t) => t.into(),
|
|
ty::TermKind::Const(c) => c.into(),
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'tcx> GenericArg<'tcx> {
|
|
#[inline]
|
|
pub fn unpack(self) -> GenericArgKind<'tcx> {
|
|
let ptr = self.ptr.get();
|
|
// SAFETY: use of `Interned::new_unchecked` here is ok because these
|
|
// pointers were originally created from `Interned` types in `pack()`,
|
|
// and this is just going in the other direction.
|
|
unsafe {
|
|
match ptr & TAG_MASK {
|
|
REGION_TAG => GenericArgKind::Lifetime(ty::Region(Interned::new_unchecked(
|
|
&*((ptr & !TAG_MASK) as *const ty::RegionKind<'tcx>),
|
|
))),
|
|
TYPE_TAG => GenericArgKind::Type(Ty(Interned::new_unchecked(
|
|
&*((ptr & !TAG_MASK) as *const WithCachedTypeInfo<ty::TyKind<'tcx>>),
|
|
))),
|
|
CONST_TAG => GenericArgKind::Const(ty::Const(Interned::new_unchecked(
|
|
&*((ptr & !TAG_MASK) as *const ty::ConstData<'tcx>),
|
|
))),
|
|
_ => intrinsics::unreachable(),
|
|
}
|
|
}
|
|
}
|
|
|
|
#[inline]
|
|
pub fn as_type(self) -> Option<Ty<'tcx>> {
|
|
match self.unpack() {
|
|
GenericArgKind::Type(ty) => Some(ty),
|
|
_ => None,
|
|
}
|
|
}
|
|
|
|
#[inline]
|
|
pub fn as_region(self) -> Option<ty::Region<'tcx>> {
|
|
match self.unpack() {
|
|
GenericArgKind::Lifetime(re) => Some(re),
|
|
_ => None,
|
|
}
|
|
}
|
|
|
|
#[inline]
|
|
pub fn as_const(self) -> Option<ty::Const<'tcx>> {
|
|
match self.unpack() {
|
|
GenericArgKind::Const(ct) => Some(ct),
|
|
_ => None,
|
|
}
|
|
}
|
|
|
|
/// Unpack the `GenericArg` as a region when it is known certainly to be a region.
|
|
pub fn expect_region(self) -> ty::Region<'tcx> {
|
|
self.as_region().unwrap_or_else(|| bug!("expected a region, but found another kind"))
|
|
}
|
|
|
|
/// Unpack the `GenericArg` as a type when it is known certainly to be a type.
|
|
/// This is true in cases where `GenericArgs` is used in places where the kinds are known
|
|
/// to be limited (e.g. in tuples, where the only parameters are type parameters).
|
|
pub fn expect_ty(self) -> Ty<'tcx> {
|
|
self.as_type().unwrap_or_else(|| bug!("expected a type, but found another kind"))
|
|
}
|
|
|
|
/// Unpack the `GenericArg` as a const when it is known certainly to be a const.
|
|
pub fn expect_const(self) -> ty::Const<'tcx> {
|
|
self.as_const().unwrap_or_else(|| bug!("expected a const, but found another kind"))
|
|
}
|
|
|
|
pub fn is_non_region_infer(self) -> bool {
|
|
match self.unpack() {
|
|
GenericArgKind::Lifetime(_) => false,
|
|
GenericArgKind::Type(ty) => ty.is_ty_or_numeric_infer(),
|
|
GenericArgKind::Const(ct) => ct.is_ct_infer(),
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'a, 'tcx> Lift<'tcx> for GenericArg<'a> {
|
|
type Lifted = GenericArg<'tcx>;
|
|
|
|
fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
|
|
match self.unpack() {
|
|
GenericArgKind::Lifetime(lt) => tcx.lift(lt).map(|lt| lt.into()),
|
|
GenericArgKind::Type(ty) => tcx.lift(ty).map(|ty| ty.into()),
|
|
GenericArgKind::Const(ct) => tcx.lift(ct).map(|ct| ct.into()),
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for GenericArg<'tcx> {
|
|
fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>(
|
|
self,
|
|
folder: &mut F,
|
|
) -> Result<Self, F::Error> {
|
|
match self.unpack() {
|
|
GenericArgKind::Lifetime(lt) => lt.try_fold_with(folder).map(Into::into),
|
|
GenericArgKind::Type(ty) => ty.try_fold_with(folder).map(Into::into),
|
|
GenericArgKind::Const(ct) => ct.try_fold_with(folder).map(Into::into),
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for GenericArg<'tcx> {
|
|
fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
|
|
match self.unpack() {
|
|
GenericArgKind::Lifetime(lt) => lt.visit_with(visitor),
|
|
GenericArgKind::Type(ty) => ty.visit_with(visitor),
|
|
GenericArgKind::Const(ct) => ct.visit_with(visitor),
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<E> for GenericArg<'tcx> {
|
|
fn encode(&self, e: &mut E) {
|
|
self.unpack().encode(e)
|
|
}
|
|
}
|
|
|
|
impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for GenericArg<'tcx> {
|
|
fn decode(d: &mut D) -> GenericArg<'tcx> {
|
|
GenericArgKind::decode(d).pack()
|
|
}
|
|
}
|
|
|
|
/// List of generic arguments that are gonna be used to replace generic parameters.
|
|
pub type GenericArgs<'tcx> = List<GenericArg<'tcx>>;
|
|
|
|
pub type GenericArgsRef<'tcx> = &'tcx GenericArgs<'tcx>;
|
|
|
|
impl<'tcx> GenericArgs<'tcx> {
|
|
/// Converts generic args to a type list.
|
|
///
|
|
/// # Panics
|
|
///
|
|
/// If any of the generic arguments are not types.
|
|
pub fn into_type_list(&self, tcx: TyCtxt<'tcx>) -> &'tcx List<Ty<'tcx>> {
|
|
tcx.mk_type_list_from_iter(self.iter().map(|arg| match arg.unpack() {
|
|
GenericArgKind::Type(ty) => ty,
|
|
_ => bug!("`into_type_list` called on generic arg with non-types"),
|
|
}))
|
|
}
|
|
|
|
/// Interpret these generic args as the args of a closure type.
|
|
/// Closure args have a particular structure controlled by the
|
|
/// compiler that encodes information like the signature and closure kind;
|
|
/// see `ty::ClosureArgs` struct for more comments.
|
|
pub fn as_closure(&'tcx self) -> ClosureArgs<'tcx> {
|
|
ClosureArgs { args: self }
|
|
}
|
|
|
|
/// Interpret these generic args as the args of a generator type.
|
|
/// Generator args have a particular structure controlled by the
|
|
/// compiler that encodes information like the signature and generator kind;
|
|
/// see `ty::GeneratorArgs` struct for more comments.
|
|
pub fn as_generator(&'tcx self) -> GeneratorArgs<'tcx> {
|
|
GeneratorArgs { args: self }
|
|
}
|
|
|
|
/// Interpret these generic args as the args of an inline const.
|
|
/// Inline const args have a particular structure controlled by the
|
|
/// compiler that encodes information like the inferred type;
|
|
/// see `ty::InlineConstArgs` struct for more comments.
|
|
pub fn as_inline_const(&'tcx self) -> InlineConstArgs<'tcx> {
|
|
InlineConstArgs { args: self }
|
|
}
|
|
|
|
/// Creates an `GenericArgs` that maps each generic parameter to itself.
|
|
pub fn identity_for_item(tcx: TyCtxt<'tcx>, def_id: impl Into<DefId>) -> GenericArgsRef<'tcx> {
|
|
Self::for_item(tcx, def_id.into(), |param, _| tcx.mk_param_from_def(param))
|
|
}
|
|
|
|
/// Creates an `GenericArgs` for generic parameter definitions,
|
|
/// by calling closures to obtain each kind.
|
|
/// The closures get to observe the `GenericArgs` as they're
|
|
/// being built, which can be used to correctly
|
|
/// replace defaults of generic parameters.
|
|
pub fn for_item<F>(tcx: TyCtxt<'tcx>, def_id: DefId, mut mk_kind: F) -> GenericArgsRef<'tcx>
|
|
where
|
|
F: FnMut(&ty::GenericParamDef, &[GenericArg<'tcx>]) -> GenericArg<'tcx>,
|
|
{
|
|
let defs = tcx.generics_of(def_id);
|
|
let count = defs.count();
|
|
let mut args = SmallVec::with_capacity(count);
|
|
Self::fill_item(&mut args, tcx, defs, &mut mk_kind);
|
|
tcx.mk_args(&args)
|
|
}
|
|
|
|
pub fn extend_to<F>(
|
|
&self,
|
|
tcx: TyCtxt<'tcx>,
|
|
def_id: DefId,
|
|
mut mk_kind: F,
|
|
) -> GenericArgsRef<'tcx>
|
|
where
|
|
F: FnMut(&ty::GenericParamDef, &[GenericArg<'tcx>]) -> GenericArg<'tcx>,
|
|
{
|
|
Self::for_item(tcx, def_id, |param, args| {
|
|
self.get(param.index as usize).cloned().unwrap_or_else(|| mk_kind(param, args))
|
|
})
|
|
}
|
|
|
|
pub fn fill_item<F>(
|
|
args: &mut SmallVec<[GenericArg<'tcx>; 8]>,
|
|
tcx: TyCtxt<'tcx>,
|
|
defs: &ty::Generics,
|
|
mk_kind: &mut F,
|
|
) where
|
|
F: FnMut(&ty::GenericParamDef, &[GenericArg<'tcx>]) -> GenericArg<'tcx>,
|
|
{
|
|
if let Some(def_id) = defs.parent {
|
|
let parent_defs = tcx.generics_of(def_id);
|
|
Self::fill_item(args, tcx, parent_defs, mk_kind);
|
|
}
|
|
Self::fill_single(args, defs, mk_kind)
|
|
}
|
|
|
|
pub fn fill_single<F>(
|
|
args: &mut SmallVec<[GenericArg<'tcx>; 8]>,
|
|
defs: &ty::Generics,
|
|
mk_kind: &mut F,
|
|
) where
|
|
F: FnMut(&ty::GenericParamDef, &[GenericArg<'tcx>]) -> GenericArg<'tcx>,
|
|
{
|
|
args.reserve(defs.params.len());
|
|
for param in &defs.params {
|
|
let kind = mk_kind(param, args);
|
|
assert_eq!(param.index as usize, args.len(), "{args:#?}, {defs:#?}");
|
|
args.push(kind);
|
|
}
|
|
}
|
|
|
|
// Extend an `original_args` list to the full number of args expected by `def_id`,
|
|
// filling in the missing parameters with error ty/ct or 'static regions.
|
|
pub fn extend_with_error(
|
|
tcx: TyCtxt<'tcx>,
|
|
def_id: DefId,
|
|
original_args: &[GenericArg<'tcx>],
|
|
) -> GenericArgsRef<'tcx> {
|
|
ty::GenericArgs::for_item(tcx, def_id, |def, args| {
|
|
if let Some(arg) = original_args.get(def.index as usize) {
|
|
*arg
|
|
} else {
|
|
def.to_error(tcx, args)
|
|
}
|
|
})
|
|
}
|
|
|
|
#[inline]
|
|
pub fn types(&'tcx self) -> impl DoubleEndedIterator<Item = Ty<'tcx>> + 'tcx {
|
|
self.iter().filter_map(|k| k.as_type())
|
|
}
|
|
|
|
#[inline]
|
|
pub fn regions(&'tcx self) -> impl DoubleEndedIterator<Item = ty::Region<'tcx>> + 'tcx {
|
|
self.iter().filter_map(|k| k.as_region())
|
|
}
|
|
|
|
#[inline]
|
|
pub fn consts(&'tcx self) -> impl DoubleEndedIterator<Item = ty::Const<'tcx>> + 'tcx {
|
|
self.iter().filter_map(|k| k.as_const())
|
|
}
|
|
|
|
/// Returns generic arguments that are not lifetimes or host effect params.
|
|
#[inline]
|
|
pub fn non_erasable_generics(
|
|
&'tcx self,
|
|
tcx: TyCtxt<'tcx>,
|
|
def_id: DefId,
|
|
) -> impl DoubleEndedIterator<Item = GenericArgKind<'tcx>> + 'tcx {
|
|
let generics = tcx.generics_of(def_id);
|
|
self.iter().enumerate().filter_map(|(i, k)| match k.unpack() {
|
|
_ if Some(i) == generics.host_effect_index => None,
|
|
ty::GenericArgKind::Lifetime(_) => None,
|
|
generic => Some(generic),
|
|
})
|
|
}
|
|
|
|
#[inline]
|
|
#[track_caller]
|
|
pub fn type_at(&self, i: usize) -> Ty<'tcx> {
|
|
self[i].as_type().unwrap_or_else(|| bug!("expected type for param #{} in {:?}", i, self))
|
|
}
|
|
|
|
#[inline]
|
|
#[track_caller]
|
|
pub fn region_at(&self, i: usize) -> ty::Region<'tcx> {
|
|
self[i]
|
|
.as_region()
|
|
.unwrap_or_else(|| bug!("expected region for param #{} in {:?}", i, self))
|
|
}
|
|
|
|
#[inline]
|
|
#[track_caller]
|
|
pub fn const_at(&self, i: usize) -> ty::Const<'tcx> {
|
|
self[i].as_const().unwrap_or_else(|| bug!("expected const for param #{} in {:?}", i, self))
|
|
}
|
|
|
|
#[inline]
|
|
#[track_caller]
|
|
pub fn type_for_def(&self, def: &ty::GenericParamDef) -> GenericArg<'tcx> {
|
|
self.type_at(def.index as usize).into()
|
|
}
|
|
|
|
/// Transform from generic args for a child of `source_ancestor`
|
|
/// (e.g., a trait or impl) to args for the same child
|
|
/// in a different item, with `target_args` as the base for
|
|
/// the target impl/trait, with the source child-specific
|
|
/// parameters (e.g., method parameters) on top of that base.
|
|
///
|
|
/// For example given:
|
|
///
|
|
/// ```no_run
|
|
/// trait X<S> { fn f<T>(); }
|
|
/// impl<U> X<U> for U { fn f<V>() {} }
|
|
/// ```
|
|
///
|
|
/// * If `self` is `[Self, S, T]`: the identity args of `f` in the trait.
|
|
/// * If `source_ancestor` is the def_id of the trait.
|
|
/// * If `target_args` is `[U]`, the args for the impl.
|
|
/// * Then we will return `[U, T]`, the arg for `f` in the impl that
|
|
/// are needed for it to match the trait.
|
|
pub fn rebase_onto(
|
|
&self,
|
|
tcx: TyCtxt<'tcx>,
|
|
source_ancestor: DefId,
|
|
target_args: GenericArgsRef<'tcx>,
|
|
) -> GenericArgsRef<'tcx> {
|
|
let defs = tcx.generics_of(source_ancestor);
|
|
tcx.mk_args_from_iter(target_args.iter().chain(self.iter().skip(defs.count())))
|
|
}
|
|
|
|
pub fn truncate_to(&self, tcx: TyCtxt<'tcx>, generics: &ty::Generics) -> GenericArgsRef<'tcx> {
|
|
tcx.mk_args_from_iter(self.iter().take(generics.count()))
|
|
}
|
|
|
|
pub fn host_effect_param(&'tcx self) -> Option<ty::Const<'tcx>> {
|
|
self.consts().rfind(|x| matches!(x.kind(), ty::ConstKind::Param(p) if p.name == sym::host))
|
|
}
|
|
|
|
pub fn print_as_list(&self) -> String {
|
|
let v = self.iter().map(|arg| arg.to_string()).collect::<Vec<_>>();
|
|
format!("[{}]", v.join(", "))
|
|
}
|
|
}
|
|
|
|
impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for GenericArgsRef<'tcx> {
|
|
fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>(
|
|
self,
|
|
folder: &mut F,
|
|
) -> Result<Self, F::Error> {
|
|
// This code is hot enough that it's worth specializing for the most
|
|
// common length lists, to avoid the overhead of `SmallVec` creation.
|
|
// The match arms are in order of frequency. The 1, 2, and 0 cases are
|
|
// typically hit in 90--99.99% of cases. When folding doesn't change
|
|
// the args, it's faster to reuse the existing args rather than
|
|
// calling `mk_args`.
|
|
match self.len() {
|
|
1 => {
|
|
let param0 = self[0].try_fold_with(folder)?;
|
|
if param0 == self[0] { Ok(self) } else { Ok(folder.interner().mk_args(&[param0])) }
|
|
}
|
|
2 => {
|
|
let param0 = self[0].try_fold_with(folder)?;
|
|
let param1 = self[1].try_fold_with(folder)?;
|
|
if param0 == self[0] && param1 == self[1] {
|
|
Ok(self)
|
|
} else {
|
|
Ok(folder.interner().mk_args(&[param0, param1]))
|
|
}
|
|
}
|
|
0 => Ok(self),
|
|
_ => ty::util::fold_list(self, folder, |tcx, v| tcx.mk_args(v)),
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for &'tcx ty::List<Ty<'tcx>> {
|
|
fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>(
|
|
self,
|
|
folder: &mut F,
|
|
) -> Result<Self, F::Error> {
|
|
// This code is fairly hot, though not as hot as `GenericArgsRef`.
|
|
//
|
|
// When compiling stage 2, I get the following results:
|
|
//
|
|
// len | total | %
|
|
// --- | --------- | -----
|
|
// 2 | 15083590 | 48.1
|
|
// 3 | 7540067 | 24.0
|
|
// 1 | 5300377 | 16.9
|
|
// 4 | 1351897 | 4.3
|
|
// 0 | 1256849 | 4.0
|
|
//
|
|
// I've tried it with some private repositories and got
|
|
// close to the same result, with 4 and 0 swapping places
|
|
// sometimes.
|
|
match self.len() {
|
|
2 => {
|
|
let param0 = self[0].try_fold_with(folder)?;
|
|
let param1 = self[1].try_fold_with(folder)?;
|
|
if param0 == self[0] && param1 == self[1] {
|
|
Ok(self)
|
|
} else {
|
|
Ok(folder.interner().mk_type_list(&[param0, param1]))
|
|
}
|
|
}
|
|
_ => ty::util::fold_list(self, folder, |tcx, v| tcx.mk_type_list(v)),
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'tcx, T: TypeVisitable<TyCtxt<'tcx>>> TypeVisitable<TyCtxt<'tcx>> for &'tcx ty::List<T> {
|
|
#[inline]
|
|
fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
|
|
self.iter().try_for_each(|t| t.visit_with(visitor))
|
|
}
|
|
}
|
|
|
|
/// Similar to [`super::Binder`] except that it tracks early bound generics, i.e. `struct Foo<T>(T)`
|
|
/// needs `T` instantiated immediately. This type primarily exists to avoid forgetting to call
|
|
/// `instantiate`.
|
|
///
|
|
/// If you don't have anything to `instantiate`, you may be looking for
|
|
/// [`instantiate_identity`](EarlyBinder::instantiate_identity) or [`skip_binder`](EarlyBinder::skip_binder).
|
|
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
|
|
#[derive(Encodable, Decodable, HashStable)]
|
|
pub struct EarlyBinder<T> {
|
|
value: T,
|
|
}
|
|
|
|
/// For early binders, you should first call `instantiate` before using any visitors.
|
|
impl<'tcx, T> !TypeFoldable<TyCtxt<'tcx>> for ty::EarlyBinder<T> {}
|
|
impl<'tcx, T> !TypeVisitable<TyCtxt<'tcx>> for ty::EarlyBinder<T> {}
|
|
|
|
impl<T> EarlyBinder<T> {
|
|
pub fn bind(value: T) -> EarlyBinder<T> {
|
|
EarlyBinder { value }
|
|
}
|
|
|
|
pub fn as_ref(&self) -> EarlyBinder<&T> {
|
|
EarlyBinder { value: &self.value }
|
|
}
|
|
|
|
pub fn map_bound_ref<F, U>(&self, f: F) -> EarlyBinder<U>
|
|
where
|
|
F: FnOnce(&T) -> U,
|
|
{
|
|
self.as_ref().map_bound(f)
|
|
}
|
|
|
|
pub fn map_bound<F, U>(self, f: F) -> EarlyBinder<U>
|
|
where
|
|
F: FnOnce(T) -> U,
|
|
{
|
|
let value = f(self.value);
|
|
EarlyBinder { value }
|
|
}
|
|
|
|
pub fn try_map_bound<F, U, E>(self, f: F) -> Result<EarlyBinder<U>, E>
|
|
where
|
|
F: FnOnce(T) -> Result<U, E>,
|
|
{
|
|
let value = f(self.value)?;
|
|
Ok(EarlyBinder { value })
|
|
}
|
|
|
|
pub fn rebind<U>(&self, value: U) -> EarlyBinder<U> {
|
|
EarlyBinder { value }
|
|
}
|
|
|
|
/// Skips the binder and returns the "bound" value.
|
|
/// This can be used to extract data that does not depend on generic parameters
|
|
/// (e.g., getting the `DefId` of the inner value or getting the number of
|
|
/// arguments of an `FnSig`). Otherwise, consider using
|
|
/// [`instantiate_identity`](EarlyBinder::instantiate_identity).
|
|
///
|
|
/// To skip the binder on `x: &EarlyBinder<T>` to obtain `&T`, leverage
|
|
/// [`EarlyBinder::as_ref`](EarlyBinder::as_ref): `x.as_ref().skip_binder()`.
|
|
///
|
|
/// See also [`Binder::skip_binder`](super::Binder::skip_binder), which is
|
|
/// the analogous operation on [`super::Binder`].
|
|
pub fn skip_binder(self) -> T {
|
|
self.value
|
|
}
|
|
}
|
|
|
|
impl<T> EarlyBinder<Option<T>> {
|
|
pub fn transpose(self) -> Option<EarlyBinder<T>> {
|
|
self.value.map(|value| EarlyBinder { value })
|
|
}
|
|
}
|
|
|
|
impl<T, U> EarlyBinder<(T, U)> {
|
|
pub fn transpose_tuple2(self) -> (EarlyBinder<T>, EarlyBinder<U>) {
|
|
let EarlyBinder { value: (lhs, rhs) } = self;
|
|
(EarlyBinder { value: lhs }, EarlyBinder { value: rhs })
|
|
}
|
|
}
|
|
|
|
impl<'tcx, 's, I: IntoIterator> EarlyBinder<I>
|
|
where
|
|
I::Item: TypeFoldable<TyCtxt<'tcx>>,
|
|
{
|
|
pub fn iter_instantiated(
|
|
self,
|
|
tcx: TyCtxt<'tcx>,
|
|
args: &'s [GenericArg<'tcx>],
|
|
) -> IterInstantiated<'s, 'tcx, I> {
|
|
IterInstantiated { it: self.value.into_iter(), tcx, args }
|
|
}
|
|
|
|
/// Similar to [`instantiate_identity`](EarlyBinder::instantiate_identity),
|
|
/// but on an iterator of `TypeFoldable` values.
|
|
pub fn instantiate_identity_iter(self) -> I::IntoIter {
|
|
self.value.into_iter()
|
|
}
|
|
}
|
|
|
|
pub struct IterInstantiated<'s, 'tcx, I: IntoIterator> {
|
|
it: I::IntoIter,
|
|
tcx: TyCtxt<'tcx>,
|
|
args: &'s [GenericArg<'tcx>],
|
|
}
|
|
|
|
impl<'tcx, I: IntoIterator> Iterator for IterInstantiated<'_, 'tcx, I>
|
|
where
|
|
I::Item: TypeFoldable<TyCtxt<'tcx>>,
|
|
{
|
|
type Item = I::Item;
|
|
|
|
fn next(&mut self) -> Option<Self::Item> {
|
|
Some(EarlyBinder { value: self.it.next()? }.instantiate(self.tcx, self.args))
|
|
}
|
|
|
|
fn size_hint(&self) -> (usize, Option<usize>) {
|
|
self.it.size_hint()
|
|
}
|
|
}
|
|
|
|
impl<'tcx, I: IntoIterator> DoubleEndedIterator for IterInstantiated<'_, 'tcx, I>
|
|
where
|
|
I::IntoIter: DoubleEndedIterator,
|
|
I::Item: TypeFoldable<TyCtxt<'tcx>>,
|
|
{
|
|
fn next_back(&mut self) -> Option<Self::Item> {
|
|
Some(EarlyBinder { value: self.it.next_back()? }.instantiate(self.tcx, self.args))
|
|
}
|
|
}
|
|
|
|
impl<'tcx, I: IntoIterator> ExactSizeIterator for IterInstantiated<'_, 'tcx, I>
|
|
where
|
|
I::IntoIter: ExactSizeIterator,
|
|
I::Item: TypeFoldable<TyCtxt<'tcx>>,
|
|
{
|
|
}
|
|
|
|
impl<'tcx, 's, I: IntoIterator> EarlyBinder<I>
|
|
where
|
|
I::Item: Deref,
|
|
<I::Item as Deref>::Target: Copy + TypeFoldable<TyCtxt<'tcx>>,
|
|
{
|
|
pub fn iter_instantiated_copied(
|
|
self,
|
|
tcx: TyCtxt<'tcx>,
|
|
args: &'s [GenericArg<'tcx>],
|
|
) -> IterInstantiatedCopied<'s, 'tcx, I> {
|
|
IterInstantiatedCopied { it: self.value.into_iter(), tcx, args }
|
|
}
|
|
|
|
/// Similar to [`instantiate_identity`](EarlyBinder::instantiate_identity),
|
|
/// but on an iterator of values that deref to a `TypeFoldable`.
|
|
pub fn instantiate_identity_iter_copied(
|
|
self,
|
|
) -> impl Iterator<Item = <I::Item as Deref>::Target> {
|
|
self.value.into_iter().map(|v| *v)
|
|
}
|
|
}
|
|
|
|
pub struct IterInstantiatedCopied<'a, 'tcx, I: IntoIterator> {
|
|
it: I::IntoIter,
|
|
tcx: TyCtxt<'tcx>,
|
|
args: &'a [GenericArg<'tcx>],
|
|
}
|
|
|
|
impl<'tcx, I: IntoIterator> Iterator for IterInstantiatedCopied<'_, 'tcx, I>
|
|
where
|
|
I::Item: Deref,
|
|
<I::Item as Deref>::Target: Copy + TypeFoldable<TyCtxt<'tcx>>,
|
|
{
|
|
type Item = <I::Item as Deref>::Target;
|
|
|
|
fn next(&mut self) -> Option<Self::Item> {
|
|
self.it.next().map(|value| EarlyBinder { value: *value }.instantiate(self.tcx, self.args))
|
|
}
|
|
|
|
fn size_hint(&self) -> (usize, Option<usize>) {
|
|
self.it.size_hint()
|
|
}
|
|
}
|
|
|
|
impl<'tcx, I: IntoIterator> DoubleEndedIterator for IterInstantiatedCopied<'_, 'tcx, I>
|
|
where
|
|
I::IntoIter: DoubleEndedIterator,
|
|
I::Item: Deref,
|
|
<I::Item as Deref>::Target: Copy + TypeFoldable<TyCtxt<'tcx>>,
|
|
{
|
|
fn next_back(&mut self) -> Option<Self::Item> {
|
|
self.it
|
|
.next_back()
|
|
.map(|value| EarlyBinder { value: *value }.instantiate(self.tcx, self.args))
|
|
}
|
|
}
|
|
|
|
impl<'tcx, I: IntoIterator> ExactSizeIterator for IterInstantiatedCopied<'_, 'tcx, I>
|
|
where
|
|
I::IntoIter: ExactSizeIterator,
|
|
I::Item: Deref,
|
|
<I::Item as Deref>::Target: Copy + TypeFoldable<TyCtxt<'tcx>>,
|
|
{
|
|
}
|
|
|
|
pub struct EarlyBinderIter<T> {
|
|
t: T,
|
|
}
|
|
|
|
impl<T: IntoIterator> EarlyBinder<T> {
|
|
pub fn transpose_iter(self) -> EarlyBinderIter<T::IntoIter> {
|
|
EarlyBinderIter { t: self.value.into_iter() }
|
|
}
|
|
}
|
|
|
|
impl<T: Iterator> Iterator for EarlyBinderIter<T> {
|
|
type Item = EarlyBinder<T::Item>;
|
|
|
|
fn next(&mut self) -> Option<Self::Item> {
|
|
self.t.next().map(|value| EarlyBinder { value })
|
|
}
|
|
|
|
fn size_hint(&self) -> (usize, Option<usize>) {
|
|
self.t.size_hint()
|
|
}
|
|
}
|
|
|
|
impl<'tcx, T: TypeFoldable<TyCtxt<'tcx>>> ty::EarlyBinder<T> {
|
|
pub fn instantiate(self, tcx: TyCtxt<'tcx>, args: &[GenericArg<'tcx>]) -> T {
|
|
let mut folder = ArgFolder { tcx, args, binders_passed: 0 };
|
|
self.value.fold_with(&mut folder)
|
|
}
|
|
|
|
/// Makes the identity replacement `T0 => T0, ..., TN => TN`.
|
|
/// Conceptually, this converts universally bound variables into placeholders
|
|
/// when inside of a given item.
|
|
///
|
|
/// For example, consider `for<T> fn foo<T>(){ .. }`:
|
|
/// - Outside of `foo`, `T` is bound (represented by the presence of `EarlyBinder`).
|
|
/// - Inside of the body of `foo`, we treat `T` as a placeholder by calling
|
|
/// `instantiate_identity` to discharge the `EarlyBinder`.
|
|
pub fn instantiate_identity(self) -> T {
|
|
self.value
|
|
}
|
|
|
|
/// Returns the inner value, but only if it contains no bound vars.
|
|
pub fn no_bound_vars(self) -> Option<T> {
|
|
if !self.value.has_param() { Some(self.value) } else { None }
|
|
}
|
|
}
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
// The actual substitution engine itself is a type folder.
|
|
|
|
struct ArgFolder<'a, 'tcx> {
|
|
tcx: TyCtxt<'tcx>,
|
|
args: &'a [GenericArg<'tcx>],
|
|
|
|
/// Number of region binders we have passed through while doing the substitution
|
|
binders_passed: u32,
|
|
}
|
|
|
|
impl<'a, 'tcx> TypeFolder<TyCtxt<'tcx>> for ArgFolder<'a, 'tcx> {
|
|
#[inline]
|
|
fn interner(&self) -> TyCtxt<'tcx> {
|
|
self.tcx
|
|
}
|
|
|
|
fn fold_binder<T: TypeFoldable<TyCtxt<'tcx>>>(
|
|
&mut self,
|
|
t: ty::Binder<'tcx, T>,
|
|
) -> ty::Binder<'tcx, T> {
|
|
self.binders_passed += 1;
|
|
let t = t.super_fold_with(self);
|
|
self.binders_passed -= 1;
|
|
t
|
|
}
|
|
|
|
fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
|
|
#[cold]
|
|
#[inline(never)]
|
|
fn region_param_out_of_range(data: ty::EarlyBoundRegion, args: &[GenericArg<'_>]) -> ! {
|
|
bug!(
|
|
"Region parameter out of range when substituting in region {} (index={}, args = {:?})",
|
|
data.name,
|
|
data.index,
|
|
args,
|
|
)
|
|
}
|
|
|
|
#[cold]
|
|
#[inline(never)]
|
|
fn region_param_invalid(data: ty::EarlyBoundRegion, other: GenericArgKind<'_>) -> ! {
|
|
bug!(
|
|
"Unexpected parameter {:?} when substituting in region {} (index={})",
|
|
other,
|
|
data.name,
|
|
data.index
|
|
)
|
|
}
|
|
|
|
// Note: This routine only handles regions that are bound on
|
|
// type declarations and other outer declarations, not those
|
|
// bound in *fn types*. Region substitution of the bound
|
|
// regions that appear in a function signature is done using
|
|
// the specialized routine `ty::replace_late_regions()`.
|
|
match *r {
|
|
ty::ReEarlyBound(data) => {
|
|
let rk = self.args.get(data.index as usize).map(|k| k.unpack());
|
|
match rk {
|
|
Some(GenericArgKind::Lifetime(lt)) => self.shift_region_through_binders(lt),
|
|
Some(other) => region_param_invalid(data, other),
|
|
None => region_param_out_of_range(data, self.args),
|
|
}
|
|
}
|
|
ty::ReLateBound(..)
|
|
| ty::ReFree(_)
|
|
| ty::ReStatic
|
|
| ty::RePlaceholder(_)
|
|
| ty::ReErased
|
|
| ty::ReError(_) => r,
|
|
ty::ReVar(_) => bug!("unexpected region: {r:?}"),
|
|
}
|
|
}
|
|
|
|
fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
|
|
if !t.has_param() {
|
|
return t;
|
|
}
|
|
|
|
match *t.kind() {
|
|
ty::Param(p) => self.ty_for_param(p, t),
|
|
_ => t.super_fold_with(self),
|
|
}
|
|
}
|
|
|
|
fn fold_const(&mut self, c: ty::Const<'tcx>) -> ty::Const<'tcx> {
|
|
if let ty::ConstKind::Param(p) = c.kind() {
|
|
self.const_for_param(p, c)
|
|
} else {
|
|
c.super_fold_with(self)
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'a, 'tcx> ArgFolder<'a, 'tcx> {
|
|
fn ty_for_param(&self, p: ty::ParamTy, source_ty: Ty<'tcx>) -> Ty<'tcx> {
|
|
// Look up the type in the args. It really should be in there.
|
|
let opt_ty = self.args.get(p.index as usize).map(|k| k.unpack());
|
|
let ty = match opt_ty {
|
|
Some(GenericArgKind::Type(ty)) => ty,
|
|
Some(kind) => self.type_param_expected(p, source_ty, kind),
|
|
None => self.type_param_out_of_range(p, source_ty),
|
|
};
|
|
|
|
self.shift_vars_through_binders(ty)
|
|
}
|
|
|
|
#[cold]
|
|
#[inline(never)]
|
|
fn type_param_expected(&self, p: ty::ParamTy, ty: Ty<'tcx>, kind: GenericArgKind<'tcx>) -> ! {
|
|
bug!(
|
|
"expected type for `{:?}` ({:?}/{}) but found {:?} when substituting, args={:?}",
|
|
p,
|
|
ty,
|
|
p.index,
|
|
kind,
|
|
self.args,
|
|
)
|
|
}
|
|
|
|
#[cold]
|
|
#[inline(never)]
|
|
fn type_param_out_of_range(&self, p: ty::ParamTy, ty: Ty<'tcx>) -> ! {
|
|
bug!(
|
|
"type parameter `{:?}` ({:?}/{}) out of range when substituting, args={:?}",
|
|
p,
|
|
ty,
|
|
p.index,
|
|
self.args,
|
|
)
|
|
}
|
|
|
|
fn const_for_param(&self, p: ParamConst, source_ct: ty::Const<'tcx>) -> ty::Const<'tcx> {
|
|
// Look up the const in the args. It really should be in there.
|
|
let opt_ct = self.args.get(p.index as usize).map(|k| k.unpack());
|
|
let ct = match opt_ct {
|
|
Some(GenericArgKind::Const(ct)) => ct,
|
|
Some(kind) => self.const_param_expected(p, source_ct, kind),
|
|
None => self.const_param_out_of_range(p, source_ct),
|
|
};
|
|
|
|
self.shift_vars_through_binders(ct)
|
|
}
|
|
|
|
#[cold]
|
|
#[inline(never)]
|
|
fn const_param_expected(
|
|
&self,
|
|
p: ty::ParamConst,
|
|
ct: ty::Const<'tcx>,
|
|
kind: GenericArgKind<'tcx>,
|
|
) -> ! {
|
|
bug!(
|
|
"expected const for `{:?}` ({:?}/{}) but found {:?} when substituting args={:?}",
|
|
p,
|
|
ct,
|
|
p.index,
|
|
kind,
|
|
self.args,
|
|
)
|
|
}
|
|
|
|
#[cold]
|
|
#[inline(never)]
|
|
fn const_param_out_of_range(&self, p: ty::ParamConst, ct: ty::Const<'tcx>) -> ! {
|
|
bug!(
|
|
"const parameter `{:?}` ({:?}/{}) out of range when substituting args={:?}",
|
|
p,
|
|
ct,
|
|
p.index,
|
|
self.args,
|
|
)
|
|
}
|
|
|
|
/// It is sometimes necessary to adjust the De Bruijn indices during substitution. This occurs
|
|
/// when we are substituting a type with escaping bound vars into a context where we have
|
|
/// passed through binders. That's quite a mouthful. Let's see an example:
|
|
///
|
|
/// ```
|
|
/// type Func<A> = fn(A);
|
|
/// type MetaFunc = for<'a> fn(Func<&'a i32>);
|
|
/// ```
|
|
///
|
|
/// The type `MetaFunc`, when fully expanded, will be
|
|
/// ```ignore (illustrative)
|
|
/// for<'a> fn(fn(&'a i32))
|
|
/// // ^~ ^~ ^~~
|
|
/// // | | |
|
|
/// // | | DebruijnIndex of 2
|
|
/// // Binders
|
|
/// ```
|
|
/// Here the `'a` lifetime is bound in the outer function, but appears as an argument of the
|
|
/// inner one. Therefore, that appearance will have a DebruijnIndex of 2, because we must skip
|
|
/// over the inner binder (remember that we count De Bruijn indices from 1). However, in the
|
|
/// definition of `MetaFunc`, the binder is not visible, so the type `&'a i32` will have a
|
|
/// De Bruijn index of 1. It's only during the substitution that we can see we must increase the
|
|
/// depth by 1 to account for the binder that we passed through.
|
|
///
|
|
/// As a second example, consider this twist:
|
|
///
|
|
/// ```
|
|
/// type FuncTuple<A> = (A,fn(A));
|
|
/// type MetaFuncTuple = for<'a> fn(FuncTuple<&'a i32>);
|
|
/// ```
|
|
///
|
|
/// Here the final type will be:
|
|
/// ```ignore (illustrative)
|
|
/// for<'a> fn((&'a i32, fn(&'a i32)))
|
|
/// // ^~~ ^~~
|
|
/// // | |
|
|
/// // DebruijnIndex of 1 |
|
|
/// // DebruijnIndex of 2
|
|
/// ```
|
|
/// As indicated in the diagram, here the same type `&'a i32` is substituted once, but in the
|
|
/// first case we do not increase the De Bruijn index and in the second case we do. The reason
|
|
/// is that only in the second case have we passed through a fn binder.
|
|
fn shift_vars_through_binders<T: TypeFoldable<TyCtxt<'tcx>>>(&self, val: T) -> T {
|
|
debug!(
|
|
"shift_vars(val={:?}, binders_passed={:?}, has_escaping_bound_vars={:?})",
|
|
val,
|
|
self.binders_passed,
|
|
val.has_escaping_bound_vars()
|
|
);
|
|
|
|
if self.binders_passed == 0 || !val.has_escaping_bound_vars() {
|
|
return val;
|
|
}
|
|
|
|
let result = ty::fold::shift_vars(TypeFolder::interner(self), val, self.binders_passed);
|
|
debug!("shift_vars: shifted result = {:?}", result);
|
|
|
|
result
|
|
}
|
|
|
|
fn shift_region_through_binders(&self, region: ty::Region<'tcx>) -> ty::Region<'tcx> {
|
|
if self.binders_passed == 0 || !region.has_escaping_bound_vars() {
|
|
return region;
|
|
}
|
|
ty::fold::shift_region(self.tcx, region, self.binders_passed)
|
|
}
|
|
}
|
|
|
|
/// Stores the user-given args to reach some fully qualified path
|
|
/// (e.g., `<T>::Item` or `<T as Trait>::Item`).
|
|
#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
|
|
#[derive(HashStable, TypeFoldable, TypeVisitable)]
|
|
pub struct UserArgs<'tcx> {
|
|
/// The args for the item as given by the user.
|
|
pub args: GenericArgsRef<'tcx>,
|
|
|
|
/// The self type, in the case of a `<T>::Item` path (when applied
|
|
/// to an inherent impl). See `UserSelfTy` below.
|
|
pub user_self_ty: Option<UserSelfTy<'tcx>>,
|
|
}
|
|
|
|
/// Specifies the user-given self type. In the case of a path that
|
|
/// refers to a member in an inherent impl, this self type is
|
|
/// sometimes needed to constrain the type parameters on the impl. For
|
|
/// example, in this code:
|
|
///
|
|
/// ```ignore (illustrative)
|
|
/// struct Foo<T> { }
|
|
/// impl<A> Foo<A> { fn method() { } }
|
|
/// ```
|
|
///
|
|
/// when you then have a path like `<Foo<&'static u32>>::method`,
|
|
/// this struct would carry the `DefId` of the impl along with the
|
|
/// self type `Foo<u32>`. Then we can instantiate the parameters of
|
|
/// the impl (with the args from `UserArgs`) and apply those to
|
|
/// the self type, giving `Foo<?A>`. Finally, we unify that with
|
|
/// the self type here, which contains `?A` to be `&'static u32`
|
|
#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
|
|
#[derive(HashStable, TypeFoldable, TypeVisitable)]
|
|
pub struct UserSelfTy<'tcx> {
|
|
pub impl_def_id: DefId,
|
|
pub self_ty: Ty<'tcx>,
|
|
}
|