Unnamed repository; edit this file 'description' to name the repository.
Remove unnecessary VarianceTerm
| -rw-r--r-- | crates/hir-ty/src/variance.rs | 105 |
1 files changed, 31 insertions, 74 deletions
diff --git a/crates/hir-ty/src/variance.rs b/crates/hir-ty/src/variance.rs index 2339e37fa1..ca16e986af 100644 --- a/crates/hir-ty/src/variance.rs +++ b/crates/hir-ty/src/variance.rs @@ -170,21 +170,6 @@ impl Variance { #[derive(Copy, Clone, Debug)] struct InferredIndex(usize); -#[derive(Clone)] -enum VarianceTerm { - ConstantTerm(Variance), - TransformTerm(Box<VarianceTerm>, Box<VarianceTerm>), -} - -impl fmt::Debug for VarianceTerm { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - match self { - VarianceTerm::ConstantTerm(c1) => write!(f, "{c1:?}"), - VarianceTerm::TransformTerm(v1, v2) => write!(f, "({v1:?} \u{00D7} {v2:?})"), - } - } -} - struct Context<'db> { db: &'db dyn HirDatabase, def: GenericDefId, @@ -200,7 +185,7 @@ struct Context<'db> { #[derive(Clone)] struct Constraint { inferred: InferredIndex, - variance: VarianceTerm, + variance: Variance, } impl Context<'_> { @@ -213,7 +198,7 @@ impl Context<'_> { for (_, field) in db.field_types(variant).iter() { self.add_constraints_from_ty( &field.clone().substitute(Interner, &subst), - &VarianceTerm::ConstantTerm(Variance::Covariant), + Variance::Covariant, ); } }; @@ -235,37 +220,22 @@ impl Context<'_> { .callable_item_signature(f.into()) .substitute(Interner, &subst) .params_and_return, - &VarianceTerm::ConstantTerm(Variance::Covariant), + Variance::Covariant, ); } _ => {} } } - fn contravariant(&mut self, variance: &VarianceTerm) -> VarianceTerm { - self.xform(variance, &VarianceTerm::ConstantTerm(Variance::Contravariant)) + fn contravariant(&mut self, variance: Variance) -> Variance { + variance.xform(Variance::Contravariant) } - fn invariant(&mut self, variance: &VarianceTerm) -> VarianceTerm { - self.xform(variance, &VarianceTerm::ConstantTerm(Variance::Invariant)) + fn invariant(&mut self, variance: Variance) -> Variance { + variance.xform(Variance::Invariant) } - fn xform(&mut self, v1: &VarianceTerm, v2: &VarianceTerm) -> VarianceTerm { - match (v1, v2) { - // Applying a "covariant" transform is always a no-op - (_, VarianceTerm::ConstantTerm(Variance::Covariant)) => v1.clone(), - (VarianceTerm::ConstantTerm(c1), VarianceTerm::ConstantTerm(c2)) => { - VarianceTerm::ConstantTerm(c1.xform(*c2)) - } - _ => VarianceTerm::TransformTerm(Box::new(v1.clone()), Box::new(v2.clone())), - } - } - - fn add_constraints_from_invariant_args( - &mut self, - args: &[GenericArg], - variance: &VarianceTerm, - ) { + fn add_constraints_from_invariant_args(&mut self, args: &[GenericArg], variance: Variance) { tracing::debug!( "add_constraints_from_invariant_args(args={:?}, variance={:?})", args, @@ -275,9 +245,9 @@ impl Context<'_> { for k in args { match k.data(Interner) { - GenericArgData::Lifetime(lt) => self.add_constraints_from_region(lt, &variance_i), - GenericArgData::Ty(ty) => self.add_constraints_from_ty(ty, &variance_i), - GenericArgData::Const(val) => self.add_constraints_from_const(val, &variance_i), + GenericArgData::Lifetime(lt) => self.add_constraints_from_region(lt, variance_i), + GenericArgData::Ty(ty) => self.add_constraints_from_ty(ty, variance_i), + GenericArgData::Const(val) => self.add_constraints_from_const(val, variance_i), } } } @@ -285,7 +255,7 @@ impl Context<'_> { /// Adds constraints appropriate for an instance of `ty` appearing /// in a context with the generics defined in `generics` and /// ambient variance `variance` - fn add_constraints_from_ty(&mut self, ty: &Ty, variance: &VarianceTerm) { + fn add_constraints_from_ty(&mut self, ty: &Ty, variance: Variance) { tracing::debug!("add_constraints_from_ty(ty={:?}, variance={:?})", ty, variance); match ty.kind(Interner) { TyKind::Scalar(_) | TyKind::Never | TyKind::Str | TyKind::Foreign(..) => { @@ -390,7 +360,7 @@ impl Context<'_> { InferredIndex(self.len_self + index) }; tracing::debug!("add_constraint(index={:?}, variance={:?})", inferred, variance); - self.constraints.push(Constraint { inferred, variance: variance.clone() }); + self.constraints.push(Constraint { inferred, variance }); } TyKind::Function(f) => { self.add_constraints_from_sig(f, variance); @@ -413,7 +383,7 @@ impl Context<'_> { &mut self, def_id: GenericDefId, args: &[GenericArg], - variance: &VarianceTerm, + variance: Variance, ) { tracing::debug!( "add_constraints_from_args(def_id={:?}, args={:?}, variance={:?})", @@ -429,13 +399,13 @@ impl Context<'_> { if def_id == self.def { // HACK: Workaround for the trivial cycle salsa case (see // recursive_one_bivariant_more_non_bivariant_params test) - let variance_i = self.xform(variance, &VarianceTerm::ConstantTerm(Variance::Bivariant)); + let variance_i = variance.xform(Variance::Bivariant); for k in args { match k.data(Interner) { GenericArgData::Lifetime(lt) => { - self.add_constraints_from_region(lt, &variance_i) + self.add_constraints_from_region(lt, variance_i) } - GenericArgData::Ty(ty) => self.add_constraints_from_ty(ty, &variance_i), + GenericArgData::Ty(ty) => self.add_constraints_from_ty(ty, variance_i), GenericArgData::Const(val) => self.add_constraints_from_const(val, variance), } } @@ -445,13 +415,12 @@ impl Context<'_> { }; for (i, k) in args.iter().enumerate() { - let variance_decl = &VarianceTerm::ConstantTerm(variances[i]); - let variance_i = self.xform(variance, variance_decl); + let variance_i = variance.xform(variances[i]); match k.data(Interner) { GenericArgData::Lifetime(lt) => { - self.add_constraints_from_region(lt, &variance_i) + self.add_constraints_from_region(lt, variance_i) } - GenericArgData::Ty(ty) => self.add_constraints_from_ty(ty, &variance_i), + GenericArgData::Ty(ty) => self.add_constraints_from_ty(ty, variance_i), GenericArgData::Const(val) => self.add_constraints_from_const(val, variance), } } @@ -460,7 +429,7 @@ impl Context<'_> { /// Adds constraints appropriate for a const expression `val` /// in a context with ambient variance `variance` - fn add_constraints_from_const(&mut self, c: &Const, variance: &VarianceTerm) { + fn add_constraints_from_const(&mut self, c: &Const, variance: Variance) { match &c.data(Interner).value { chalk_ir::ConstValue::Concrete(c) => { if let ConstScalar::UnevaluatedConst(_, subst) = &c.interned { @@ -473,27 +442,27 @@ impl Context<'_> { /// Adds constraints appropriate for a function with signature /// `sig` appearing in a context with ambient variance `variance` - fn add_constraints_from_sig(&mut self, sig: &FnPointer, variance: &VarianceTerm) { + fn add_constraints_from_sig(&mut self, sig: &FnPointer, variance: Variance) { let contra = self.contravariant(variance); let mut tys = sig.substitution.0.iter(Interner).filter_map(move |p| p.ty(Interner)); self.add_constraints_from_ty(tys.next_back().unwrap(), variance); for input in tys { - self.add_constraints_from_ty(input, &contra); + self.add_constraints_from_ty(input, contra); } } - fn add_constraints_from_sig2(&mut self, sig: &[Ty], variance: &VarianceTerm) { + fn add_constraints_from_sig2(&mut self, sig: &[Ty], variance: Variance) { let contra = self.contravariant(variance); let mut tys = sig.iter(); self.add_constraints_from_ty(tys.next_back().unwrap(), variance); for input in tys { - self.add_constraints_from_ty(input, &contra); + self.add_constraints_from_ty(input, contra); } } /// Adds constraints appropriate for a region appearing in a /// context with ambient variance `variance` - fn add_constraints_from_region(&mut self, region: &Lifetime, variance: &VarianceTerm) { + fn add_constraints_from_region(&mut self, region: &Lifetime, variance: Variance) { match region.data(Interner) { // FIXME: chalk has no params? LifetimeData::Placeholder(index) => { @@ -532,11 +501,11 @@ impl Context<'_> { /// Adds constraints appropriate for a mutability-type pair /// appearing in a context with ambient variance `variance` - fn add_constraints_from_mt(&mut self, ty: &Ty, mt: Mutability, variance: &VarianceTerm) { + fn add_constraints_from_mt(&mut self, ty: &Ty, mt: Mutability, variance: Variance) { match mt { Mutability::Mut => { let invar = self.invariant(variance); - self.add_constraints_from_ty(ty, &invar); + self.add_constraints_from_ty(ty, invar); } Mutability::Not => { @@ -559,13 +528,12 @@ impl Context<'_> { changed = false; for constraint in &self.constraints { - let Constraint { inferred, variance: term } = constraint; + let &Constraint { inferred, variance } = constraint; let InferredIndex(inferred) = inferred; - let variance = Self::evaluate(term); - let old_value = solutions[*inferred]; + let old_value = solutions[inferred]; let new_value = variance.glb(old_value); if old_value != new_value { - solutions[*inferred] = new_value; + solutions[inferred] = new_value; changed = true; } } @@ -590,17 +558,6 @@ impl Context<'_> { solutions } - - fn evaluate(term: &VarianceTerm) -> Variance { - match term { - VarianceTerm::ConstantTerm(v) => *v, - VarianceTerm::TransformTerm(t1, t2) => { - let v1 = Self::evaluate(t1); - let v2 = Self::evaluate(t2); - v1.xform(v2) - } - } - } } #[cfg(test)] |