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Auto merge of rust-lang#79169 - LeSeulArtichaut:ty-lib, r=nikomatsakis
Create `rustc_type_ir` Decided to start small 😄 This PR creates a `rustc_type_ir` crate as part of the WG-Traits plan to create a shared type library. ~~There already exists a `rustc_ty` crate, so I named the new crate `rustc_ty_library`. However I think it would make sense to rename the current `rustc_ty` to something else (e.g. `rustc_ty_passes`) to free the name for this new crate.~~ r? `@jackh726`
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‎Cargo.lock‎

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@@ -3932,6 +3932,7 @@ dependencies = [
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"rustc_session",
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"rustc_span",
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"rustc_target",
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"rustc_type_ir",
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"smallvec 1.4.2",
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"tracing",
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]
@@ -4266,6 +4267,16 @@ dependencies = [
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"tracing",
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]
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[[package]]
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name = "rustc_type_ir"
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version = "0.0.0"
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dependencies = [
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"bitflags",
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"rustc_data_structures",
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"rustc_index",
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"rustc_serialize",
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]
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[[package]]
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name = "rustc_typeck"
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version = "0.0.0"

‎compiler/rustc_middle/Cargo.toml‎

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@@ -30,3 +30,4 @@ chalk-ir = "0.36.0"
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smallvec = { version = "1.0", features = ["union", "may_dangle"] }
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measureme = "9.0.0"
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rustc_session = { path = "../rustc_session" }
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rustc_type_ir = { path = "../rustc_type_ir" }

‎compiler/rustc_middle/src/ty/mod.rs‎

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@@ -56,7 +56,7 @@ pub use self::sty::InferTy::*;
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pub use self::sty::RegionKind;
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pub use self::sty::RegionKind::*;
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pub use self::sty::TyKind::*;
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pub use self::sty::{Binder, BoundTy, BoundTyKind, BoundVar, DebruijnIndex, INNERMOST};
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pub use self::sty::{Binder, BoundTy, BoundTyKind, BoundVar};
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pub use self::sty::{BoundRegion, EarlyBoundRegion, FreeRegion, Region};
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pub use self::sty::{CanonicalPolyFnSig, FnSig, GenSig, PolyFnSig, PolyGenSig};
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pub use self::sty::{ClosureSubsts, GeneratorSubsts, TypeAndMut, UpvarSubsts};
@@ -67,6 +67,7 @@ pub use self::sty::{ExistentialProjection, PolyExistentialProjection};
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pub use self::sty::{ExistentialTraitRef, PolyExistentialTraitRef};
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pub use self::sty::{PolyTraitRef, TraitRef, TyKind};
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pub use crate::ty::diagnostics::*;
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pub use rustc_type_ir::{DebruijnIndex, TypeFlags, INNERMOST};
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pub use self::binding::BindingMode;
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pub use self::binding::BindingMode::*;
@@ -497,91 +498,6 @@ pub struct CReaderCacheKey {
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pub pos: usize,
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}
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bitflags! {
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/// Flags that we track on types. These flags are propagated upwards
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/// through the type during type construction, so that we can quickly check
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/// whether the type has various kinds of types in it without recursing
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/// over the type itself.
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pub struct TypeFlags: u32 {
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// Does this have parameters? Used to determine whether substitution is
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// required.
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/// Does this have [Param]?
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const HAS_TY_PARAM = 1 << 0;
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/// Does this have [ReEarlyBound]?
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const HAS_RE_PARAM = 1 << 1;
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/// Does this have [ConstKind::Param]?
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const HAS_CT_PARAM = 1 << 2;
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const NEEDS_SUBST = TypeFlags::HAS_TY_PARAM.bits
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| TypeFlags::HAS_RE_PARAM.bits
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| TypeFlags::HAS_CT_PARAM.bits;
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/// Does this have [Infer]?
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const HAS_TY_INFER = 1 << 3;
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/// Does this have [ReVar]?
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const HAS_RE_INFER = 1 << 4;
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/// Does this have [ConstKind::Infer]?
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const HAS_CT_INFER = 1 << 5;
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/// Does this have inference variables? Used to determine whether
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/// inference is required.
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const NEEDS_INFER = TypeFlags::HAS_TY_INFER.bits
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| TypeFlags::HAS_RE_INFER.bits
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| TypeFlags::HAS_CT_INFER.bits;
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/// Does this have [Placeholder]?
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const HAS_TY_PLACEHOLDER = 1 << 6;
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/// Does this have [RePlaceholder]?
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const HAS_RE_PLACEHOLDER = 1 << 7;
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/// Does this have [ConstKind::Placeholder]?
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const HAS_CT_PLACEHOLDER = 1 << 8;
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/// `true` if there are "names" of regions and so forth
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/// that are local to a particular fn/inferctxt
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const HAS_FREE_LOCAL_REGIONS = 1 << 9;
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/// `true` if there are "names" of types and regions and so forth
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/// that are local to a particular fn
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const HAS_FREE_LOCAL_NAMES = TypeFlags::HAS_TY_PARAM.bits
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| TypeFlags::HAS_CT_PARAM.bits
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| TypeFlags::HAS_TY_INFER.bits
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| TypeFlags::HAS_CT_INFER.bits
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| TypeFlags::HAS_TY_PLACEHOLDER.bits
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| TypeFlags::HAS_CT_PLACEHOLDER.bits
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| TypeFlags::HAS_FREE_LOCAL_REGIONS.bits;
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/// Does this have [Projection]?
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const HAS_TY_PROJECTION = 1 << 10;
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/// Does this have [Opaque]?
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const HAS_TY_OPAQUE = 1 << 11;
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/// Does this have [ConstKind::Unevaluated]?
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const HAS_CT_PROJECTION = 1 << 12;
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/// Could this type be normalized further?
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const HAS_PROJECTION = TypeFlags::HAS_TY_PROJECTION.bits
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| TypeFlags::HAS_TY_OPAQUE.bits
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| TypeFlags::HAS_CT_PROJECTION.bits;
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/// Is an error type/const reachable?
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const HAS_ERROR = 1 << 13;
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/// Does this have any region that "appears free" in the type?
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/// Basically anything but [ReLateBound] and [ReErased].
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const HAS_FREE_REGIONS = 1 << 14;
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/// Does this have any [ReLateBound] regions? Used to check
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/// if a global bound is safe to evaluate.
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const HAS_RE_LATE_BOUND = 1 << 15;
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/// Does this have any [ReErased] regions?
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const HAS_RE_ERASED = 1 << 16;
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/// Does this value have parameters/placeholders/inference variables which could be
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/// replaced later, in a way that would change the results of `impl` specialization?
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const STILL_FURTHER_SPECIALIZABLE = 1 << 17;
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}
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}
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#[allow(rustc::usage_of_ty_tykind)]
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pub struct TyS<'tcx> {
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/// This field shouldn't be used directly and may be removed in the future.

‎compiler/rustc_middle/src/ty/sty.rs‎

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@@ -1289,53 +1289,6 @@ impl<'tcx> ParamConst {
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}
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}
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rustc_index::newtype_index! {
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/// A [De Bruijn index][dbi] is a standard means of representing
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/// regions (and perhaps later types) in a higher-ranked setting. In
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/// particular, imagine a type like this:
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///
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/// for<'a> fn(for<'b> fn(&'b isize, &'a isize), &'a char)
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/// ^ ^ | | |
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/// | | | | |
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/// | +------------+ 0 | |
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/// | | |
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/// +----------------------------------+ 1 |
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/// | |
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/// +----------------------------------------------+ 0
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///
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/// In this type, there are two binders (the outer fn and the inner
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/// fn). We need to be able to determine, for any given region, which
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/// fn type it is bound by, the inner or the outer one. There are
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/// various ways you can do this, but a De Bruijn index is one of the
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/// more convenient and has some nice properties. The basic idea is to
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/// count the number of binders, inside out. Some examples should help
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/// clarify what I mean.
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///
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/// Let's start with the reference type `&'b isize` that is the first
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/// argument to the inner function. This region `'b` is assigned a De
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/// Bruijn index of 0, meaning "the innermost binder" (in this case, a
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/// fn). The region `'a` that appears in the second argument type (`&'a
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/// isize`) would then be assigned a De Bruijn index of 1, meaning "the
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/// second-innermost binder". (These indices are written on the arrays
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/// in the diagram).
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///
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/// What is interesting is that De Bruijn index attached to a particular
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/// variable will vary depending on where it appears. For example,
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/// the final type `&'a char` also refers to the region `'a` declared on
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/// the outermost fn. But this time, this reference is not nested within
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/// any other binders (i.e., it is not an argument to the inner fn, but
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/// rather the outer one). Therefore, in this case, it is assigned a
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/// De Bruijn index of 0, because the innermost binder in that location
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/// is the outer fn.
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///
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/// [dbi]: https://en.wikipedia.org/wiki/De_Bruijn_index
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#[derive(HashStable)]
1333-
pub struct DebruijnIndex {
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DEBUG_FORMAT = "DebruijnIndex({})",
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const INNERMOST = 0,
1336-
}
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}
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13391292
pub type Region<'tcx> = &'tcx RegionKind;
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/// Representation of regions. Note that the NLL checker uses a distinct
@@ -1450,7 +1403,7 @@ pub enum RegionKind {
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14511404
/// Region bound in a function scope, which will be substituted when the
14521405
/// function is called.
1453-
ReLateBound(DebruijnIndex, BoundRegion),
1406+
ReLateBound(ty::DebruijnIndex, BoundRegion),
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14551408
/// When checking a function body, the types of all arguments and so forth
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/// that refer to bound region parameters are modified to refer to free
@@ -1614,65 +1567,6 @@ impl<'tcx> PolyExistentialProjection<'tcx> {
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}
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}
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1617-
impl DebruijnIndex {
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/// Returns the resulting index when this value is moved into
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/// `amount` number of new binders. So, e.g., if you had
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///
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/// for<'a> fn(&'a x)
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///
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/// and you wanted to change it to
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///
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/// for<'a> fn(for<'b> fn(&'a x))
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///
1627-
/// you would need to shift the index for `'a` into a new binder.
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#[must_use]
1629-
pub fn shifted_in(self, amount: u32) -> DebruijnIndex {
1630-
DebruijnIndex::from_u32(self.as_u32() + amount)
1631-
}
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1633-
/// Update this index in place by shifting it "in" through
1634-
/// `amount` number of binders.
1635-
pub fn shift_in(&mut self, amount: u32) {
1636-
*self = self.shifted_in(amount);
1637-
}
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1639-
/// Returns the resulting index when this value is moved out from
1640-
/// `amount` number of new binders.
1641-
#[must_use]
1642-
pub fn shifted_out(self, amount: u32) -> DebruijnIndex {
1643-
DebruijnIndex::from_u32(self.as_u32() - amount)
1644-
}
1645-
1646-
/// Update in place by shifting out from `amount` binders.
1647-
pub fn shift_out(&mut self, amount: u32) {
1648-
*self = self.shifted_out(amount);
1649-
}
1650-
1651-
/// Adjusts any De Bruijn indices so as to make `to_binder` the
1652-
/// innermost binder. That is, if we have something bound at `to_binder`,
1653-
/// it will now be bound at INNERMOST. This is an appropriate thing to do
1654-
/// when moving a region out from inside binders:
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///
1656-
/// ```
1657-
/// for<'a> fn(for<'b> for<'c> fn(&'a u32), _)
1658-
/// // Binder: D3 D2 D1 ^^
1659-
/// ```
1660-
///
1661-
/// Here, the region `'a` would have the De Bruijn index D3,
1662-
/// because it is the bound 3 binders out. However, if we wanted
1663-
/// to refer to that region `'a` in the second argument (the `_`),
1664-
/// those two binders would not be in scope. In that case, we
1665-
/// might invoke `shift_out_to_binder(D3)`. This would adjust the
1666-
/// De Bruijn index of `'a` to D1 (the innermost binder).
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///
1668-
/// If we invoke `shift_out_to_binder` and the region is in fact
1669-
/// bound by one of the binders we are shifting out of, that is an
1670-
/// error (and should fail an assertion failure).
1671-
pub fn shifted_out_to_binder(self, to_binder: DebruijnIndex) -> Self {
1672-
self.shifted_out(to_binder.as_u32() - INNERMOST.as_u32())
1673-
}
1674-
}
1675-
16761570
/// Region utilities
16771571
impl RegionKind {
16781572
/// Is this region named by the user?
@@ -1703,7 +1597,7 @@ impl RegionKind {
17031597
}
17041598
}
17051599

1706-
pub fn bound_at_or_above_binder(&self, index: DebruijnIndex) -> bool {
1600+
pub fn bound_at_or_above_binder(&self, index: ty::DebruijnIndex) -> bool {
17071601
match *self {
17081602
ty::ReLateBound(debruijn, _) => debruijn >= index,
17091603
_ => false,

‎compiler/rustc_type_ir/Cargo.toml‎

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@@ -0,0 +1,14 @@
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[package]
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name = "rustc_type_ir"
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version = "0.0.0"
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authors = ["The Rust Project Developers"]
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edition = "2018"
6+
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[lib]
8+
doctest = false
9+
10+
[dependencies]
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bitflags = "1.2.1"
12+
rustc_index = { path = "../rustc_index" }
13+
rustc_serialize = { path = "../rustc_serialize" }
14+
rustc_data_structures = { path = "../rustc_data_structures" }

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