diff --git a/Cargo.lock b/Cargo.lock index c2c06a2adb1..bea1879e793 100644 --- a/Cargo.lock +++ b/Cargo.lock @@ -4314,6 +4314,7 @@ dependencies = [ "bitflags", "rustc_data_structures", "rustc_index", + "rustc_macros", "rustc_serialize", ] diff --git a/compiler/rustc_middle/src/infer/unify_key.rs b/compiler/rustc_middle/src/infer/unify_key.rs index 16e9aafb25a..8318bdefc8e 100644 --- a/compiler/rustc_middle/src/infer/unify_key.rs +++ b/compiler/rustc_middle/src/infer/unify_key.rs @@ -1,4 +1,4 @@ -use crate::ty::{self, FloatVarValue, InferConst, IntVarValue, Ty, TyCtxt}; +use crate::ty::{self, InferConst, Ty, TyCtxt}; use rustc_data_structures::snapshot_vec; use rustc_data_structures::undo_log::UndoLogs; use rustc_data_structures::unify::{ @@ -15,36 +15,6 @@ pub trait ToType { fn to_type<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx>; } -/// Raw `TyVid` are used as the unification key for `sub_relations`; -/// they carry no values. -impl UnifyKey for ty::TyVid { - type Value = (); - fn index(&self) -> u32 { - self.index - } - fn from_index(i: u32) -> ty::TyVid { - ty::TyVid { index: i } - } - fn tag() -> &'static str { - "TyVid" - } -} - -impl UnifyKey for ty::IntVid { - type Value = Option; - fn index(&self) -> u32 { - self.index - } - fn from_index(i: u32) -> ty::IntVid { - ty::IntVid { index: i } - } - fn tag() -> &'static str { - "IntVid" - } -} - -impl EqUnifyValue for IntVarValue {} - #[derive(PartialEq, Copy, Clone, Debug)] pub struct RegionVidKey { /// The minimum region vid in the unification set. This is needed @@ -80,7 +50,7 @@ impl UnifyKey for ty::RegionVid { } } -impl ToType for IntVarValue { +impl ToType for ty::IntVarValue { fn to_type<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { match *self { ty::IntType(i) => tcx.mk_mach_int(i), @@ -89,24 +59,7 @@ impl ToType for IntVarValue { } } -// Floating point type keys - -impl UnifyKey for ty::FloatVid { - type Value = Option; - fn index(&self) -> u32 { - self.index - } - fn from_index(i: u32) -> ty::FloatVid { - ty::FloatVid { index: i } - } - fn tag() -> &'static str { - "FloatVid" - } -} - -impl EqUnifyValue for FloatVarValue {} - -impl ToType for FloatVarValue { +impl ToType for ty::FloatVarValue { fn to_type<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { tcx.mk_mach_float(self.0) } diff --git a/compiler/rustc_middle/src/ty/diagnostics.rs b/compiler/rustc_middle/src/ty/diagnostics.rs index 3adcdbe591f..e386d973ee4 100644 --- a/compiler/rustc_middle/src/ty/diagnostics.rs +++ b/compiler/rustc_middle/src/ty/diagnostics.rs @@ -1,8 +1,7 @@ //! Diagnostics related methods for `TyS`. -use crate::ty::sty::InferTy; use crate::ty::TyKind::*; -use crate::ty::{TyCtxt, TyS}; +use crate::ty::{InferTy, TyCtxt, TyS}; use rustc_errors::{Applicability, DiagnosticBuilder}; use rustc_hir as hir; use rustc_hir::def_id::DefId; diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs index c6970df0178..87730197da0 100644 --- a/compiler/rustc_middle/src/ty/mod.rs +++ b/compiler/rustc_middle/src/ty/mod.rs @@ -65,7 +65,6 @@ use std::ptr; use std::str; pub use self::sty::BoundRegionKind::*; -pub use self::sty::InferTy::*; pub use self::sty::RegionKind; pub use self::sty::RegionKind::*; pub use self::sty::TyKind::*; @@ -74,13 +73,14 @@ pub use self::sty::{BoundRegion, BoundRegionKind, EarlyBoundRegion, FreeRegion, pub use self::sty::{CanonicalPolyFnSig, FnSig, GenSig, PolyFnSig, PolyGenSig}; pub use self::sty::{ClosureSubsts, GeneratorSubsts, TypeAndMut, UpvarSubsts}; pub use self::sty::{ClosureSubstsParts, GeneratorSubstsParts}; -pub use self::sty::{ConstVid, FloatVid, IntVid, RegionVid, TyVid}; -pub use self::sty::{ExistentialPredicate, InferTy, ParamConst, ParamTy, ProjectionTy}; +pub use self::sty::{ConstVid, RegionVid}; +pub use self::sty::{ExistentialPredicate, 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::*; -pub use rustc_type_ir::{DebruijnIndex, TypeFlags, INNERMOST}; +pub use rustc_type_ir::InferTy::*; +pub use rustc_type_ir::*; pub use self::binding::BindingMode; pub use self::binding::BindingMode::*; @@ -421,14 +421,6 @@ impl Visibility { } } -#[derive(Copy, Clone, PartialEq, TyDecodable, TyEncodable, HashStable)] -pub enum Variance { - Covariant, // T <: T iff A <: B -- e.g., function return type - Invariant, // T <: T iff B == A -- e.g., type of mutable cell - Contravariant, // T <: T iff B <: A -- e.g., function param type - Bivariant, // T <: T -- e.g., unused type parameter -} - /// The crate variances map is computed during typeck and contains the /// variance of every item in the local crate. You should not use it /// directly, because to do so will make your pass dependent on the @@ -443,66 +435,6 @@ pub struct CrateVariancesMap<'tcx> { pub variances: FxHashMap, } -impl Variance { - /// `a.xform(b)` combines the variance of a context with the - /// variance of a type with the following meaning. If we are in a - /// context with variance `a`, and we encounter a type argument in - /// a position with variance `b`, then `a.xform(b)` is the new - /// variance with which the argument appears. - /// - /// Example 1: - /// - /// *mut Vec - /// - /// Here, the "ambient" variance starts as covariant. `*mut T` is - /// invariant with respect to `T`, so the variance in which the - /// `Vec` appears is `Covariant.xform(Invariant)`, which - /// yields `Invariant`. Now, the type `Vec` is covariant with - /// respect to its type argument `T`, and hence the variance of - /// the `i32` here is `Invariant.xform(Covariant)`, which results - /// (again) in `Invariant`. - /// - /// Example 2: - /// - /// fn(*const Vec, *mut Vec` appears is - /// `Contravariant.xform(Covariant)` or `Contravariant`. The same - /// is true for its `i32` argument. In the `*mut T` case, the - /// variance of `Vec` is `Contravariant.xform(Invariant)`, - /// and hence the outermost type is `Invariant` with respect to - /// `Vec` (and its `i32` argument). - /// - /// Source: Figure 1 of "Taming the Wildcards: - /// Combining Definition- and Use-Site Variance" published in PLDI'11. - pub fn xform(self, v: ty::Variance) -> ty::Variance { - match (self, v) { - // Figure 1, column 1. - (ty::Covariant, ty::Covariant) => ty::Covariant, - (ty::Covariant, ty::Contravariant) => ty::Contravariant, - (ty::Covariant, ty::Invariant) => ty::Invariant, - (ty::Covariant, ty::Bivariant) => ty::Bivariant, - - // Figure 1, column 2. - (ty::Contravariant, ty::Covariant) => ty::Contravariant, - (ty::Contravariant, ty::Contravariant) => ty::Covariant, - (ty::Contravariant, ty::Invariant) => ty::Invariant, - (ty::Contravariant, ty::Bivariant) => ty::Bivariant, - - // Figure 1, column 3. - (ty::Invariant, _) => ty::Invariant, - - // Figure 1, column 4. - (ty::Bivariant, _) => ty::Bivariant, - } - } -} - // Contains information needed to resolve types and (in the future) look up // the types of AST nodes. #[derive(Copy, Clone, PartialEq, Eq, Hash)] @@ -804,15 +736,6 @@ pub struct CaptureInfo<'tcx> { pub type UpvarListMap = FxHashMap>; pub type UpvarCaptureMap<'tcx> = FxHashMap>; -#[derive(Clone, Copy, PartialEq, Eq)] -pub enum IntVarValue { - IntType(ast::IntTy), - UintType(ast::UintTy), -} - -#[derive(Clone, Copy, PartialEq, Eq)] -pub struct FloatVarValue(pub ast::FloatTy); - impl ty::EarlyBoundRegion { /// Does this early bound region have a name? Early bound regions normally /// always have names except when using anonymous lifetimes (`'_`). diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs index 8911de41c6d..9c7e0e60c14 100644 --- a/compiler/rustc_middle/src/ty/print/pretty.rs +++ b/compiler/rustc_middle/src/ty/print/pretty.rs @@ -557,14 +557,19 @@ pub trait PrettyPrinter<'tcx>: } ty::FnPtr(ref bare_fn) => p!(print(bare_fn)), ty::Infer(infer_ty) => { + let verbose = self.tcx().sess.verbose(); if let ty::TyVar(ty_vid) = infer_ty { if let Some(name) = self.infer_ty_name(ty_vid) { p!(write("{}", name)) } else { - p!(write("{}", infer_ty)) + if verbose { + p!(write("{:?}", infer_ty)) + } else { + p!(write("{}", infer_ty)) + } } } else { - p!(write("{}", infer_ty)) + if verbose { p!(write("{:?}", infer_ty)) } else { p!(write("{}", infer_ty)) } } } ty::Error(_) => p!("[type error]"), @@ -1246,7 +1251,7 @@ pub struct FmtPrinterData<'a, 'tcx, F> { pub region_highlight_mode: RegionHighlightMode, - pub name_resolver: Option Option>>, + pub name_resolver: Option Option>>, } impl Deref for FmtPrinter<'a, 'tcx, F> { @@ -2007,21 +2012,6 @@ define_print_and_forward_display! { p!("fn", pretty_fn_sig(self.inputs(), self.c_variadic, self.output())); } - ty::InferTy { - if cx.tcx().sess.verbose() { - p!(write("{:?}", self)); - return Ok(cx); - } - match *self { - ty::TyVar(_) => p!("_"), - ty::IntVar(_) => p!(write("{}", "{integer}")), - ty::FloatVar(_) => p!(write("{}", "{float}")), - ty::FreshTy(v) => p!(write("FreshTy({})", v)), - ty::FreshIntTy(v) => p!(write("FreshIntTy({})", v)), - ty::FreshFloatTy(v) => p!(write("FreshFloatTy({})", v)) - } - } - ty::TraitRef<'tcx> { p!(write("<{} as {}>", self.self_ty(), self.print_only_trait_path())) } diff --git a/compiler/rustc_middle/src/ty/structural_impls.rs b/compiler/rustc_middle/src/ty/structural_impls.rs index 44c173e356d..0ca94a9f180 100644 --- a/compiler/rustc_middle/src/ty/structural_impls.rs +++ b/compiler/rustc_middle/src/ty/structural_impls.rs @@ -111,81 +111,24 @@ impl fmt::Debug for ty::FreeRegion { } } -impl fmt::Debug for ty::Variance { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - f.write_str(match *self { - ty::Covariant => "+", - ty::Contravariant => "-", - ty::Invariant => "o", - ty::Bivariant => "*", - }) - } -} - impl fmt::Debug for ty::FnSig<'tcx> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!(f, "({:?}; c_variadic: {})->{:?}", self.inputs(), self.c_variadic, self.output()) } } -impl fmt::Debug for ty::TyVid { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - write!(f, "_#{}t", self.index) - } -} - impl<'tcx> fmt::Debug for ty::ConstVid<'tcx> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!(f, "_#{}c", self.index) } } -impl fmt::Debug for ty::IntVid { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - write!(f, "_#{}i", self.index) - } -} - -impl fmt::Debug for ty::FloatVid { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - write!(f, "_#{}f", self.index) - } -} - impl fmt::Debug for ty::RegionVid { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!(f, "'_#{}r", self.index()) } } -impl fmt::Debug for ty::InferTy { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - match *self { - ty::TyVar(ref v) => v.fmt(f), - ty::IntVar(ref v) => v.fmt(f), - ty::FloatVar(ref v) => v.fmt(f), - ty::FreshTy(v) => write!(f, "FreshTy({:?})", v), - ty::FreshIntTy(v) => write!(f, "FreshIntTy({:?})", v), - ty::FreshFloatTy(v) => write!(f, "FreshFloatTy({:?})", v), - } - } -} - -impl fmt::Debug for ty::IntVarValue { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - match *self { - ty::IntType(ref v) => v.fmt(f), - ty::UintType(ref v) => v.fmt(f), - } - } -} - -impl fmt::Debug for ty::FloatVarValue { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - self.0.fmt(f) - } -} - impl fmt::Debug for ty::TraitRef<'tcx> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { with_no_trimmed_paths(|| fmt::Display::fmt(self, f)) @@ -274,7 +217,7 @@ TrivialTypeFoldableAndLiftImpls! { u64, String, crate::middle::region::Scope, - ::rustc_ast::FloatTy, + crate::ty::FloatTy, ::rustc_ast::InlineAsmOptions, ::rustc_ast::InlineAsmTemplatePiece, ::rustc_ast::NodeId, diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs index e53977b5eb9..aeba1843dbc 100644 --- a/compiler/rustc_middle/src/ty/sty.rs +++ b/compiler/rustc_middle/src/ty/sty.rs @@ -2,11 +2,11 @@ #![allow(rustc::usage_of_ty_tykind)] -use self::InferTy::*; use self::TyKind::*; use crate::infer::canonical::Canonical; use crate::ty::subst::{GenericArg, InternalSubsts, Subst, SubstsRef}; +use crate::ty::InferTy::{self, *}; use crate::ty::{ self, AdtDef, DefIdTree, Discr, Ty, TyCtxt, TypeFlags, TypeFoldable, WithConstness, }; @@ -1426,12 +1426,6 @@ pub struct EarlyBoundRegion { pub name: Symbol, } -/// A **ty**pe **v**ariable **ID**. -#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)] -pub struct TyVid { - pub index: u32, -} - /// A **`const`** **v**ariable **ID**. #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)] pub struct ConstVid<'tcx> { @@ -1439,18 +1433,6 @@ pub struct ConstVid<'tcx> { pub phantom: PhantomData<&'tcx ()>, } -/// An **int**egral (`u32`, `i32`, `usize`, etc.) type **v**ariable **ID**. -#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)] -pub struct IntVid { - pub index: u32, -} - -/// An **float**ing-point (`f32` or `f64`) type **v**ariable **ID**. -#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)] -pub struct FloatVid { - pub index: u32, -} - rustc_index::newtype_index! { /// A **region** (lifetime) **v**ariable **ID**. pub struct RegionVid { @@ -1464,43 +1446,6 @@ impl Atom for RegionVid { } } -/// A placeholder for a type that hasn't been inferred yet. -/// -/// E.g., if we have an empty array (`[]`), then we create a fresh -/// type variable for the element type since we won't know until it's -/// used what the element type is supposed to be. -#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)] -#[derive(HashStable)] -pub enum InferTy { - /// A type variable. - TyVar(TyVid), - /// An integral type variable (`{integer}`). - /// - /// These are created when the compiler sees an integer literal like - /// `1` that could be several different types (`u8`, `i32`, `u32`, etc.). - /// We don't know until it's used what type it's supposed to be, so - /// we create a fresh type variable. - IntVar(IntVid), - /// A floating-point type variable (`{float}`). - /// - /// These are created when the compiler sees an float literal like - /// `1.0` that could be either an `f32` or an `f64`. - /// We don't know until it's used what type it's supposed to be, so - /// we create a fresh type variable. - FloatVar(FloatVid), - - /// A [`FreshTy`][Self::FreshTy] is one that is generated as a replacement - /// for an unbound type variable. This is convenient for caching etc. See - /// `rustc_infer::infer::freshen` for more details. - /// - /// Compare with [`TyVar`][Self::TyVar]. - FreshTy(u32), - /// Like [`FreshTy`][Self::FreshTy], but as a replacement for [`IntVar`][Self::IntVar]. - FreshIntTy(u32), - /// Like [`FreshTy`][Self::FreshTy], but as a replacement for [`FloatVar`][Self::FloatVar]. - FreshFloatTy(u32), -} - rustc_index::newtype_index! { pub struct BoundVar { .. } } diff --git a/compiler/rustc_type_ir/Cargo.toml b/compiler/rustc_type_ir/Cargo.toml index d50451b7794..3f64bd89997 100644 --- a/compiler/rustc_type_ir/Cargo.toml +++ b/compiler/rustc_type_ir/Cargo.toml @@ -12,3 +12,4 @@ bitflags = "1.2.1" rustc_index = { path = "../rustc_index" } rustc_serialize = { path = "../rustc_serialize" } rustc_data_structures = { path = "../rustc_data_structures" } +rustc_macros = { path = "../rustc_macros" } diff --git a/compiler/rustc_type_ir/src/lib.rs b/compiler/rustc_type_ir/src/lib.rs index 37abb4496ac..7e70af21c03 100644 --- a/compiler/rustc_type_ir/src/lib.rs +++ b/compiler/rustc_type_ir/src/lib.rs @@ -4,8 +4,13 @@ #[macro_use] extern crate bitflags; +#[macro_use] +extern crate rustc_macros; use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; +use rustc_data_structures::unify::{EqUnifyValue, UnifyKey}; +use std::fmt; +use std::mem::discriminant; bitflags! { /// Flags that we track on types. These flags are propagated upwards @@ -197,8 +202,409 @@ impl DebruijnIndex { } } +#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)] +#[derive(Encodable, Decodable)] +pub enum IntTy { + Isize, + I8, + I16, + I32, + I64, + I128, +} + +impl IntTy { + pub fn name_str(&self) -> &'static str { + match *self { + IntTy::Isize => "isize", + IntTy::I8 => "i8", + IntTy::I16 => "i16", + IntTy::I32 => "i32", + IntTy::I64 => "i64", + IntTy::I128 => "i128", + } + } + + pub fn bit_width(&self) -> Option { + Some(match *self { + IntTy::Isize => return None, + IntTy::I8 => 8, + IntTy::I16 => 16, + IntTy::I32 => 32, + IntTy::I64 => 64, + IntTy::I128 => 128, + }) + } + + pub fn normalize(&self, target_width: u32) -> Self { + match self { + IntTy::Isize => match target_width { + 16 => IntTy::I16, + 32 => IntTy::I32, + 64 => IntTy::I64, + _ => unreachable!(), + }, + _ => *self, + } + } +} + +#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Copy, Debug)] +#[derive(Encodable, Decodable)] +pub enum UintTy { + Usize, + U8, + U16, + U32, + U64, + U128, +} + +impl UintTy { + pub fn name_str(&self) -> &'static str { + match *self { + UintTy::Usize => "usize", + UintTy::U8 => "u8", + UintTy::U16 => "u16", + UintTy::U32 => "u32", + UintTy::U64 => "u64", + UintTy::U128 => "u128", + } + } + + pub fn bit_width(&self) -> Option { + Some(match *self { + UintTy::Usize => return None, + UintTy::U8 => 8, + UintTy::U16 => 16, + UintTy::U32 => 32, + UintTy::U64 => 64, + UintTy::U128 => 128, + }) + } + + pub fn normalize(&self, target_width: u32) -> Self { + match self { + UintTy::Usize => match target_width { + 16 => UintTy::U16, + 32 => UintTy::U32, + 64 => UintTy::U64, + _ => unreachable!(), + }, + _ => *self, + } + } +} + +#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)] +#[derive(Encodable, Decodable)] +pub enum FloatTy { + F32, + F64, +} + +impl FloatTy { + pub fn name_str(self) -> &'static str { + match self { + FloatTy::F32 => "f32", + FloatTy::F64 => "f64", + } + } + + pub fn bit_width(self) -> u64 { + match self { + FloatTy::F32 => 32, + FloatTy::F64 => 64, + } + } +} + +#[derive(Clone, Copy, PartialEq, Eq)] +pub enum IntVarValue { + IntType(IntTy), + UintType(UintTy), +} + +#[derive(Clone, Copy, PartialEq, Eq)] +pub struct FloatVarValue(pub FloatTy); + +/// A **ty**pe **v**ariable **ID**. +#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Encodable, Decodable)] +pub struct TyVid { + pub index: u32, +} + +/// An **int**egral (`u32`, `i32`, `usize`, etc.) type **v**ariable **ID**. +#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Encodable, Decodable)] +pub struct IntVid { + pub index: u32, +} + +/// An **float**ing-point (`f32` or `f64`) type **v**ariable **ID**. +#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Encodable, Decodable)] +pub struct FloatVid { + pub index: u32, +} + +/// A placeholder for a type that hasn't been inferred yet. +/// +/// E.g., if we have an empty array (`[]`), then we create a fresh +/// type variable for the element type since we won't know until it's +/// used what the element type is supposed to be. +#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Encodable, Decodable)] +pub enum InferTy { + /// A type variable. + TyVar(TyVid), + /// An integral type variable (`{integer}`). + /// + /// These are created when the compiler sees an integer literal like + /// `1` that could be several different types (`u8`, `i32`, `u32`, etc.). + /// We don't know until it's used what type it's supposed to be, so + /// we create a fresh type variable. + IntVar(IntVid), + /// A floating-point type variable (`{float}`). + /// + /// These are created when the compiler sees an float literal like + /// `1.0` that could be either an `f32` or an `f64`. + /// We don't know until it's used what type it's supposed to be, so + /// we create a fresh type variable. + FloatVar(FloatVid), + + /// A [`FreshTy`][Self::FreshTy] is one that is generated as a replacement + /// for an unbound type variable. This is convenient for caching etc. See + /// `rustc_infer::infer::freshen` for more details. + /// + /// Compare with [`TyVar`][Self::TyVar]. + FreshTy(u32), + /// Like [`FreshTy`][Self::FreshTy], but as a replacement for [`IntVar`][Self::IntVar]. + FreshIntTy(u32), + /// Like [`FreshTy`][Self::FreshTy], but as a replacement for [`FloatVar`][Self::FloatVar]. + FreshFloatTy(u32), +} + +/// Raw `TyVid` are used as the unification key for `sub_relations`; +/// they carry no values. +impl UnifyKey for TyVid { + type Value = (); + fn index(&self) -> u32 { + self.index + } + fn from_index(i: u32) -> TyVid { + TyVid { index: i } + } + fn tag() -> &'static str { + "TyVid" + } +} + +impl EqUnifyValue for IntVarValue {} + +impl UnifyKey for IntVid { + type Value = Option; + fn index(&self) -> u32 { + self.index + } + fn from_index(i: u32) -> IntVid { + IntVid { index: i } + } + fn tag() -> &'static str { + "IntVid" + } +} + +impl EqUnifyValue for FloatVarValue {} + +impl UnifyKey for FloatVid { + type Value = Option; + fn index(&self) -> u32 { + self.index + } + fn from_index(i: u32) -> FloatVid { + FloatVid { index: i } + } + fn tag() -> &'static str { + "FloatVid" + } +} + +#[derive(Copy, Clone, PartialEq, Decodable, Encodable)] +pub enum Variance { + Covariant, // T <: T iff A <: B -- e.g., function return type + Invariant, // T <: T iff B == A -- e.g., type of mutable cell + Contravariant, // T <: T iff B <: A -- e.g., function param type + Bivariant, // T <: T -- e.g., unused type parameter +} + +impl Variance { + /// `a.xform(b)` combines the variance of a context with the + /// variance of a type with the following meaning. If we are in a + /// context with variance `a`, and we encounter a type argument in + /// a position with variance `b`, then `a.xform(b)` is the new + /// variance with which the argument appears. + /// + /// Example 1: + /// + /// *mut Vec + /// + /// Here, the "ambient" variance starts as covariant. `*mut T` is + /// invariant with respect to `T`, so the variance in which the + /// `Vec` appears is `Covariant.xform(Invariant)`, which + /// yields `Invariant`. Now, the type `Vec` is covariant with + /// respect to its type argument `T`, and hence the variance of + /// the `i32` here is `Invariant.xform(Covariant)`, which results + /// (again) in `Invariant`. + /// + /// Example 2: + /// + /// fn(*const Vec, *mut Vec` appears is + /// `Contravariant.xform(Covariant)` or `Contravariant`. The same + /// is true for its `i32` argument. In the `*mut T` case, the + /// variance of `Vec` is `Contravariant.xform(Invariant)`, + /// and hence the outermost type is `Invariant` with respect to + /// `Vec` (and its `i32` argument). + /// + /// Source: Figure 1 of "Taming the Wildcards: + /// Combining Definition- and Use-Site Variance" published in PLDI'11. + pub fn xform(self, v: Variance) -> Variance { + match (self, v) { + // Figure 1, column 1. + (Variance::Covariant, Variance::Covariant) => Variance::Covariant, + (Variance::Covariant, Variance::Contravariant) => Variance::Contravariant, + (Variance::Covariant, Variance::Invariant) => Variance::Invariant, + (Variance::Covariant, Variance::Bivariant) => Variance::Bivariant, + + // Figure 1, column 2. + (Variance::Contravariant, Variance::Covariant) => Variance::Contravariant, + (Variance::Contravariant, Variance::Contravariant) => Variance::Covariant, + (Variance::Contravariant, Variance::Invariant) => Variance::Invariant, + (Variance::Contravariant, Variance::Bivariant) => Variance::Bivariant, + + // Figure 1, column 3. + (Variance::Invariant, _) => Variance::Invariant, + + // Figure 1, column 4. + (Variance::Bivariant, _) => Variance::Bivariant, + } + } +} + impl HashStable for DebruijnIndex { fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) { self.as_u32().hash_stable(ctx, hasher); } } + +impl HashStable for IntTy { + fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) { + discriminant(self).hash_stable(ctx, hasher); + } +} + +impl HashStable for UintTy { + fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) { + discriminant(self).hash_stable(ctx, hasher); + } +} + +impl HashStable for FloatTy { + fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) { + discriminant(self).hash_stable(ctx, hasher); + } +} + +impl HashStable for InferTy { + fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) { + use InferTy::*; + match self { + TyVar(v) => v.index.hash_stable(ctx, hasher), + IntVar(v) => v.index.hash_stable(ctx, hasher), + FloatVar(v) => v.index.hash_stable(ctx, hasher), + FreshTy(v) | FreshIntTy(v) | FreshFloatTy(v) => v.hash_stable(ctx, hasher), + } + } +} + +impl HashStable for Variance { + fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) { + discriminant(self).hash_stable(ctx, hasher); + } +} + +impl fmt::Debug for IntVarValue { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match *self { + IntVarValue::IntType(ref v) => v.fmt(f), + IntVarValue::UintType(ref v) => v.fmt(f), + } + } +} + +impl fmt::Debug for FloatVarValue { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + self.0.fmt(f) + } +} + +impl fmt::Debug for TyVid { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "_#{}t", self.index) + } +} + +impl fmt::Debug for IntVid { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "_#{}i", self.index) + } +} + +impl fmt::Debug for FloatVid { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "_#{}f", self.index) + } +} + +impl fmt::Debug for InferTy { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + use InferTy::*; + match *self { + TyVar(ref v) => v.fmt(f), + IntVar(ref v) => v.fmt(f), + FloatVar(ref v) => v.fmt(f), + FreshTy(v) => write!(f, "FreshTy({:?})", v), + FreshIntTy(v) => write!(f, "FreshIntTy({:?})", v), + FreshFloatTy(v) => write!(f, "FreshFloatTy({:?})", v), + } + } +} + +impl fmt::Debug for Variance { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.write_str(match *self { + Variance::Covariant => "+", + Variance::Contravariant => "-", + Variance::Invariant => "o", + Variance::Bivariant => "*", + }) + } +} + +impl fmt::Display for InferTy { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + use InferTy::*; + match *self { + TyVar(_) => write!(f, "_"), + IntVar(_) => write!(f, "{}", "{integer}"), + FloatVar(_) => write!(f, "{}", "{float}"), + FreshTy(v) => write!(f, "FreshTy({})", v), + FreshIntTy(v) => write!(f, "FreshIntTy({})", v), + FreshFloatTy(v) => write!(f, "FreshFloatTy({})", v), + } + } +}