Merge #7823

7823: Being Ty::InferenceVar closer to chalk equivalent r=flodiebold a=Veykril



Co-authored-by: Lukas Wirth <[email protected]>

Author: bors[bot]

crates/hir/src/code_model.rs

@@ -33,7 +33,7 @@ use hir_ty::{
     traits::{FnTrait, Solution, SolutionVariables},
     BoundVar, CallableDefId, CallableSig, Canonical, DebruijnIndex, GenericPredicate,
     InEnvironment, Obligation, ProjectionPredicate, ProjectionTy, Scalar, Substs, TraitEnvironment,
-    Ty, TyDefId, TyKind,
+    Ty, TyDefId, TyVariableKind,
 };
 use rustc_hash::FxHashSet;
 use stdx::{format_to, impl_from};
@@ -1655,7 +1655,7 @@ impl Type {
                 self.ty.environment.clone(),
                 Obligation::Projection(predicate),
             ),
-            kinds: Arc::new([TyKind::General]),
+            kinds: Arc::new([TyVariableKind::General]),
         };
 
         match db.trait_solve(self.krate, goal)? {

crates/hir_ty/src/autoderef.rs

@@ -89,8 +89,10 @@ fn deref_by_trait(
 
     let in_env = InEnvironment { value: obligation, environment: ty.environment };
 
-    let canonical =
-        Canonical::new(in_env, ty.value.kinds.iter().copied().chain(Some(super::TyKind::General)));
+    let canonical = Canonical::new(
+        in_env,
+        ty.value.kinds.iter().copied().chain(Some(chalk_ir::TyVariableKind::General)),
+    );
 
     let solution = db.trait_solve(krate, canonical)?;
 

crates/hir_ty/src/display.rs

@@ -565,7 +565,7 @@ impl HirDisplay for Ty {
                 }
                 write!(f, "{{unknown}}")?;
             }
-            Ty::Infer(..) => write!(f, "_")?,
+            Ty::InferenceVar(..) => write!(f, "_")?,
         }
         Ok(())
     }

crates/hir_ty/src/infer.rs

@@ -36,12 +36,11 @@ use stdx::impl_from;
 use syntax::SmolStr;
 
 use super::{
-    primitive::{FloatTy, IntTy},
     traits::{Guidance, Obligation, ProjectionPredicate, Solution},
     InEnvironment, ProjectionTy, Substs, TraitEnvironment, TraitRef, Ty, TypeWalk,
 };
 use crate::{
-    db::HirDatabase, infer::diagnostics::InferenceDiagnostic, lower::ImplTraitLoweringMode, Scalar,
+    db::HirDatabase, infer::diagnostics::InferenceDiagnostic, lower::ImplTraitLoweringMode,
 };
 
 pub(crate) use unify::unify;
@@ -655,30 +654,17 @@ impl<'a> InferenceContext<'a> {
 /// two are used for inference of literal values (e.g. `100` could be one of
 /// several integer types).
 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
-pub enum InferTy {
-    TypeVar(unify::TypeVarId),
-    IntVar(unify::TypeVarId),
-    FloatVar(unify::TypeVarId),
-    MaybeNeverTypeVar(unify::TypeVarId),
+pub struct InferenceVar {
+    index: u32,
 }
 
-impl InferTy {
+impl InferenceVar {
     fn to_inner(self) -> unify::TypeVarId {
-        match self {
-            InferTy::TypeVar(ty)
-            | InferTy::IntVar(ty)
-            | InferTy::FloatVar(ty)
-            | InferTy::MaybeNeverTypeVar(ty) => ty,
-        }
+        unify::TypeVarId(self.index)
     }
 
-    fn fallback_value(self) -> Ty {
-        match self {
-            InferTy::TypeVar(..) => Ty::Unknown,
-            InferTy::IntVar(..) => Ty::Scalar(Scalar::Int(IntTy::I32)),
-            InferTy::FloatVar(..) => Ty::Scalar(Scalar::Float(FloatTy::F64)),
-            InferTy::MaybeNeverTypeVar(..) => Ty::Never,
-        }
+    fn from_inner(unify::TypeVarId(index): unify::TypeVarId) -> Self {
+        InferenceVar { index }
     }
 }
 

crates/hir_ty/src/infer/coerce.rs

@@ -4,12 +4,13 @@
 //!
 //! See: https://doc.rust-lang.org/nomicon/coercions.html
 
+use chalk_ir::TyVariableKind;
 use hir_def::{lang_item::LangItemTarget, type_ref::Mutability};
 use test_utils::mark;
 
 use crate::{autoderef, traits::Solution, Obligation, Substs, TraitRef, Ty};
 
-use super::{unify::TypeVarValue, InEnvironment, InferTy, InferenceContext};
+use super::{InEnvironment, InferenceContext};
 
 impl<'a> InferenceContext<'a> {
     /// Unify two types, but may coerce the first one to the second one
@@ -53,9 +54,8 @@ impl<'a> InferenceContext<'a> {
     fn coerce_inner(&mut self, mut from_ty: Ty, to_ty: &Ty) -> bool {
         match (&from_ty, to_ty) {
             // Never type will make type variable to fallback to Never Type instead of Unknown.
-            (Ty::Never, Ty::Infer(InferTy::TypeVar(tv))) => {
-                let var = self.table.new_maybe_never_type_var();
-                self.table.var_unification_table.union_value(*tv, TypeVarValue::Known(var));
+            (Ty::Never, Ty::InferenceVar(tv, TyVariableKind::General)) => {
+                self.table.type_variable_table.set_diverging(*tv, true);
                 return true;
             }
             (Ty::Never, _) => return true,

crates/hir_ty/src/infer/expr.rs

@@ -3,6 +3,7 @@
 use std::iter::{repeat, repeat_with};
 use std::{mem, sync::Arc};
 
+use chalk_ir::TyVariableKind;
 use hir_def::{
     expr::{Array, BinaryOp, Expr, ExprId, Literal, Statement, UnaryOp},
     path::{GenericArg, GenericArgs},
@@ -18,8 +19,8 @@ use crate::{
     primitive::{self, UintTy},
     traits::{FnTrait, InEnvironment},
     utils::{generics, variant_data, Generics},
-    Binders, CallableDefId, FnPointer, FnSig, InferTy, Mutability, Obligation, OpaqueTyId, Rawness,
-    Scalar, Substs, TraitRef, Ty,
+    Binders, CallableDefId, FnPointer, FnSig, Mutability, Obligation, OpaqueTyId, Rawness, Scalar,
+    Substs, TraitRef, Ty,
 };
 
 use super::{
@@ -527,8 +528,8 @@ impl<'a> InferenceContext<'a> {
                             Ty::Scalar(Scalar::Int(_))
                             | Ty::Scalar(Scalar::Uint(_))
                             | Ty::Scalar(Scalar::Float(_))
-                            | Ty::Infer(InferTy::IntVar(..))
-                            | Ty::Infer(InferTy::FloatVar(..)) => inner_ty,
+                            | Ty::InferenceVar(_, TyVariableKind::Integer)
+                            | Ty::InferenceVar(_, TyVariableKind::Float) => inner_ty,
                             // Otherwise we resolve via the std::ops::Neg trait
                             _ => self
                                 .resolve_associated_type(inner_ty, self.resolve_ops_neg_output()),
@@ -540,7 +541,7 @@ impl<'a> InferenceContext<'a> {
                             Ty::Scalar(Scalar::Bool)
                             | Ty::Scalar(Scalar::Int(_))
                             | Ty::Scalar(Scalar::Uint(_))
-                            | Ty::Infer(InferTy::IntVar(..)) => inner_ty,
+                            | Ty::InferenceVar(_, TyVariableKind::Integer) => inner_ty,
                             // Otherwise we resolve via the std::ops::Not trait
                             _ => self
                                 .resolve_associated_type(inner_ty, self.resolve_ops_not_output()),
@@ -761,7 +762,7 @@ impl<'a> InferenceContext<'a> {
             // `!`).
             if self.diverges.is_always() {
                 // we don't even make an attempt at coercion
-                self.table.new_maybe_never_type_var()
+                self.table.new_maybe_never_var()
             } else {
                 self.coerce(&Ty::unit(), expected.coercion_target());
                 Ty::unit()