Lift FnPointer into a struct

8 files changed, 93 insertions, 81 deletions

diff --git a/crates/hir_ty/src/display.rs b/crates/hir_ty/src/display.rs
index 4a25a49e3..179f7ff44 100644
--- a/crates/hir_ty/src/display.rs
+++ b/crates/hir_ty/src/display.rs
@@ -3,8 +3,8 @@
 use std::{borrow::Cow, fmt};
 
 use crate::{
-    db::HirDatabase, primitive, utils::generics, CallableDefId, FnSig, GenericPredicate, Lifetime,
-    Obligation, OpaqueTy, OpaqueTyId, ProjectionTy, Scalar, Substs, TraitRef, Ty,
+    db::HirDatabase, primitive, utils::generics, CallableDefId, CallableSig, GenericPredicate,
+    Lifetime, Obligation, OpaqueTy, OpaqueTyId, ProjectionTy, Scalar, Substs, TraitRef, Ty,
 };
 use arrayvec::ArrayVec;
 use hir_def::{
@@ -341,8 +341,8 @@ impl HirDisplay for Ty {
                     write!(f, ")")?;
                 }
             }
-            Ty::FnPtr { is_varargs, substs, .. } => {
-                let sig = FnSig::from_fn_ptr_substs(&substs, *is_varargs);
+            Ty::Function(fn_ptr) => {
+                let sig = CallableSig::from_fn_ptr(fn_ptr);
                 sig.hir_fmt(f)?;
             }
             Ty::FnDef(def, parameters) => {
@@ -494,7 +494,7 @@ impl HirDisplay for Ty {
                     }
                 }
             }
-            Ty::Closure { substs, .. } => {
+            Ty::Closure(.., substs) => {
                 let sig = substs[0].callable_sig(f.db);
                 if let Some(sig) = sig {
                     if sig.params().is_empty() {
@@ -571,7 +571,7 @@ impl HirDisplay for Ty {
     }
 }
 
-impl HirDisplay for FnSig {
+impl HirDisplay for CallableSig {
     fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
         write!(f, "fn(")?;
         f.write_joined(self.params(), ", ")?;
diff --git a/crates/hir_ty/src/infer/coerce.rs b/crates/hir_ty/src/infer/coerce.rs
index cd5fb3252..4cca35904 100644
--- a/crates/hir_ty/src/infer/coerce.rs
+++ b/crates/hir_ty/src/infer/coerce.rs
@@ -89,14 +89,14 @@ impl<'a> InferenceContext<'a> {
             | (Ty::Ref(Mutability::Shared, ..), Ty::Ref(Mutability::Mut, ..)) => return false,
 
             // `{function_type}` -> `fn()`
-            (Ty::FnDef(..), Ty::FnPtr { .. }) => match from_ty.callable_sig(self.db) {
+            (Ty::FnDef(..), Ty::Function { .. }) => match from_ty.callable_sig(self.db) {
                 None => return false,
                 Some(sig) => {
                     from_ty = Ty::fn_ptr(sig);
                 }
             },
 
-            (Ty::Closure { substs, .. }, Ty::FnPtr { .. }) => {
+            (Ty::Closure(.., substs), Ty::Function { .. }) => {
                 from_ty = substs[0].clone();
             }
 
diff --git a/crates/hir_ty/src/infer/expr.rs b/crates/hir_ty/src/infer/expr.rs
index 13240f790..b75d32b85 100644
--- a/crates/hir_ty/src/infer/expr.rs
+++ b/crates/hir_ty/src/infer/expr.rs
@@ -18,8 +18,8 @@ use crate::{
     primitive::{self, UintTy},
     traits::{FnTrait, InEnvironment},
     utils::{generics, variant_data, Generics},
-    Binders, CallableDefId, InferTy, Mutability, Obligation, OpaqueTyId, Rawness, Scalar, Substs,
-    TraitRef, Ty,
+    Binders, CallableDefId, FnPointer, FnSig, InferTy, Mutability, Obligation, OpaqueTyId, Rawness,
+    Scalar, Substs, TraitRef, Ty,
 };
 
 use super::{
@@ -247,13 +247,12 @@ impl<'a> InferenceContext<'a> {
                     None => self.table.new_type_var(),
                 };
                 sig_tys.push(ret_ty.clone());
-                let sig_ty = Ty::FnPtr {
-                    num_args: sig_tys.len() as u16 - 1,
-                    is_varargs: false,
+                let sig_ty = Ty::Function(FnPointer {
+                    num_args: sig_tys.len() - 1,
+                    sig: FnSig { variadic: false },
                     substs: Substs(sig_tys.clone().into()),
-                };
-                let closure_ty =
-                    Ty::Closure { def: self.owner, expr: tgt_expr, substs: Substs::single(sig_ty) };
+                });
+                let closure_ty = Ty::Closure(self.owner, tgt_expr, Substs::single(sig_ty));
 
                 // Eagerly try to relate the closure type with the expected
                 // type, otherwise we often won't have enough information to
diff --git a/crates/hir_ty/src/lib.rs b/crates/hir_ty/src/lib.rs
index 4c0ebcfe3..1abb0440f 100644
--- a/crates/hir_ty/src/lib.rs
+++ b/crates/hir_ty/src/lib.rs
@@ -99,6 +99,18 @@ impl TypeWalk for ProjectionTy {
     }
 }
 
+#[derive(Clone, Copy, PartialEq, Eq, Debug, Hash)]
+pub struct FnSig {
+    pub variadic: bool,
+}
+
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub struct FnPointer {
+    pub num_args: usize,
+    pub sig: FnSig,
+    pub substs: Substs,
+}
+
 /// A type.
 ///
 /// See also the `TyKind` enum in rustc (librustc/ty/sty.rs), which represents
@@ -166,7 +178,7 @@ pub enum Ty {
     ///
     /// The closure signature is stored in a `FnPtr` type in the first type
     /// parameter.
-    Closure { def: DefWithBodyId, expr: ExprId, substs: Substs },
+    Closure(DefWithBodyId, ExprId, Substs),
 
     /// Represents a foreign type declared in external blocks.
     ForeignType(TypeAliasId),
@@ -179,8 +191,7 @@ pub enum Ty {
     /// fn foo() -> i32 { 1 }
     /// let bar: fn() -> i32 = foo;
     /// ```
-    // FIXME make this a Ty variant like in Chalk
-    FnPtr { num_args: u16, is_varargs: bool, substs: Substs },
+    Function(FnPointer),
 
     /// A "projection" type corresponds to an (unnormalized)
     /// projection like `<P0 as Trait<P1..Pn>>::Foo`. Note that the
@@ -535,22 +546,29 @@ pub enum TyKind {
 /// A function signature as seen by type inference: Several parameter types and
 /// one return type.
 #[derive(Clone, PartialEq, Eq, Debug)]
-pub struct FnSig {
+pub struct CallableSig {
     params_and_return: Arc<[Ty]>,
     is_varargs: bool,
 }
 
 /// A polymorphic function signature.
-pub type PolyFnSig = Binders<FnSig>;
+pub type PolyFnSig = Binders<CallableSig>;
 
-impl FnSig {
-    pub fn from_params_and_return(mut params: Vec<Ty>, ret: Ty, is_varargs: bool) -> FnSig {
+impl CallableSig {
+    pub fn from_params_and_return(mut params: Vec<Ty>, ret: Ty, is_varargs: bool) -> CallableSig {
         params.push(ret);
-        FnSig { params_and_return: params.into(), is_varargs }
+        CallableSig { params_and_return: params.into(), is_varargs }
+    }
+
+    pub fn from_fn_ptr(fn_ptr: &FnPointer) -> CallableSig {
+        CallableSig {
+            params_and_return: Arc::clone(&fn_ptr.substs.0),
+            is_varargs: fn_ptr.sig.variadic,
+        }
     }
 
-    pub fn from_fn_ptr_substs(substs: &Substs, is_varargs: bool) -> FnSig {
-        FnSig { params_and_return: Arc::clone(&substs.0), is_varargs }
+    pub fn from_substs(substs: &Substs) -> CallableSig {
+        CallableSig { params_and_return: Arc::clone(&substs.0), is_varargs: false }
     }
 
     pub fn params(&self) -> &[Ty] {
@@ -562,7 +580,7 @@ impl FnSig {
     }
 }
 
-impl TypeWalk for FnSig {
+impl TypeWalk for CallableSig {
     fn walk(&self, f: &mut impl FnMut(&Ty)) {
         for t in self.params_and_return.iter() {
             t.walk(f);
@@ -585,12 +603,12 @@ impl Ty {
         Ty::Tuple(0, Substs::empty())
     }
 
-    pub fn fn_ptr(sig: FnSig) -> Self {
-        Ty::FnPtr {
-            num_args: sig.params().len() as u16,
-            is_varargs: sig.is_varargs,
+    pub fn fn_ptr(sig: CallableSig) -> Self {
+        Ty::Function(FnPointer {
+            num_args: sig.params().len(),
+            sig: FnSig { variadic: sig.is_varargs },
             substs: Substs(sig.params_and_return),
-        }
+        })
     }
 
     pub fn builtin(builtin: BuiltinType) -> Self {
@@ -673,7 +691,7 @@ impl Ty {
             (Ty::OpaqueType(ty_id, ..), Ty::OpaqueType(ty_id2, ..)) => ty_id == ty_id2,
             (Ty::AssociatedType(ty_id, ..), Ty::AssociatedType(ty_id2, ..))
             | (Ty::ForeignType(ty_id, ..), Ty::ForeignType(ty_id2, ..)) => ty_id == ty_id2,
-            (Ty::Closure { def, expr, .. }, Ty::Closure { def: def2, expr: expr2, .. }) => {
+            (Ty::Closure(def, expr, _), Ty::Closure(def2, expr2, _)) => {
                 expr == expr2 && def == def2
             }
             (Ty::Ref(mutability, ..), Ty::Ref(mutability2, ..))
@@ -681,9 +699,9 @@ impl Ty {
                 mutability == mutability2
             }
             (
-                Ty::FnPtr { num_args, is_varargs, .. },
-                Ty::FnPtr { num_args: num_args2, is_varargs: is_varargs2, .. },
-            ) => num_args == num_args2 && is_varargs == is_varargs2,
+                Ty::Function(FnPointer { num_args, sig, .. }),
+                Ty::Function(FnPointer { num_args: num_args2, sig: sig2, .. }),
+            ) => num_args == num_args2 && sig == sig2,
             (Ty::Tuple(cardinality, _), Ty::Tuple(cardinality2, _)) => cardinality == cardinality2,
             (Ty::Str, Ty::Str) | (Ty::Never, Ty::Never) => true,
             (Ty::Scalar(scalar), Ty::Scalar(scalar2)) => scalar == scalar2,
@@ -722,17 +740,15 @@ impl Ty {
         }
     }
 
-    pub fn callable_sig(&self, db: &dyn HirDatabase) -> Option<FnSig> {
+    pub fn callable_sig(&self, db: &dyn HirDatabase) -> Option<CallableSig> {
         match self {
-            Ty::FnPtr { is_varargs, substs: parameters, .. } => {
-                Some(FnSig::from_fn_ptr_substs(&parameters, *is_varargs))
-            }
+            Ty::Function(fn_ptr) => Some(CallableSig::from_fn_ptr(fn_ptr)),
             Ty::FnDef(def, parameters) => {
                 let sig = db.callable_item_signature(*def);
                 Some(sig.subst(&parameters))
             }
-            Ty::Closure { substs: parameters, .. } => {
-                let sig_param = &parameters[0];
+            Ty::Closure(.., substs) => {
+                let sig_param = &substs[0];
                 sig_param.callable_sig(db)
             }
             _ => None,
@@ -751,11 +767,11 @@ impl Ty {
             | Ty::RawPtr(_, substs)
             | Ty::Ref(_, substs)
             | Ty::FnDef(_, substs)
-            | Ty::FnPtr { substs, .. }
+            | Ty::Function(FnPointer { substs, .. })
             | Ty::Tuple(_, substs)
             | Ty::OpaqueType(_, substs)
             | Ty::AssociatedType(_, substs)
-            | Ty::Closure { substs, .. } => {
+            | Ty::Closure(.., substs) => {
                 assert_eq!(substs.len(), new_substs.len());
                 *substs = new_substs;
             }
@@ -774,11 +790,11 @@ impl Ty {
             | Ty::RawPtr(_, substs)
             | Ty::Ref(_, substs)
             | Ty::FnDef(_, substs)
-            | Ty::FnPtr { substs, .. }
+            | Ty::Function(FnPointer { substs, .. })
             | Ty::Tuple(_, substs)
             | Ty::OpaqueType(_, substs)
             | Ty::AssociatedType(_, substs)
-            | Ty::Closure { substs, .. } => Some(substs),
+            | Ty::Closure(.., substs) => Some(substs),
             _ => None,
         }
     }
@@ -791,11 +807,11 @@ impl Ty {
             | Ty::RawPtr(_, substs)
             | Ty::Ref(_, substs)
             | Ty::FnDef(_, substs)
-            | Ty::FnPtr { substs, .. }
+            | Ty::Function(FnPointer { substs, .. })
             | Ty::Tuple(_, substs)
             | Ty::OpaqueType(_, substs)
             | Ty::AssociatedType(_, substs)
-            | Ty::Closure { substs, .. } => Some(substs),
+            | Ty::Closure(.., substs) => Some(substs),
             _ => None,
         }
     }
diff --git a/crates/hir_ty/src/lower.rs b/crates/hir_ty/src/lower.rs
index 84734bc0b..44bd95a9a 100644
--- a/crates/hir_ty/src/lower.rs
+++ b/crates/hir_ty/src/lower.rs
@@ -31,9 +31,9 @@ use crate::{
         all_super_trait_refs, associated_type_by_name_including_super_traits, generics,
         make_mut_slice, variant_data,
     },
-    Binders, BoundVar, DebruijnIndex, FnSig, GenericPredicate, OpaqueTy, OpaqueTyId, PolyFnSig,
-    ProjectionPredicate, ProjectionTy, ReturnTypeImplTrait, ReturnTypeImplTraits, Substs,
-    TraitEnvironment, TraitRef, Ty, TypeWalk,
+    Binders, BoundVar, CallableSig, DebruijnIndex, FnPointer, FnSig, GenericPredicate, OpaqueTy,
+    OpaqueTyId, PolyFnSig, ProjectionPredicate, ProjectionTy, ReturnTypeImplTrait,
+    ReturnTypeImplTraits, Substs, TraitEnvironment, TraitRef, Ty, TypeWalk,
 };
 
 #[derive(Debug)]
@@ -173,8 +173,12 @@ impl Ty {
             }
             TypeRef::Placeholder => Ty::Unknown,
             TypeRef::Fn(params, is_varargs) => {
-                let sig = Substs(params.iter().map(|tr| Ty::from_hir(ctx, tr)).collect());
-                Ty::FnPtr { num_args: sig.len() as u16 - 1, is_varargs: *is_varargs, substs: sig }
+                let substs = Substs(params.iter().map(|tr| Ty::from_hir(ctx, tr)).collect());
+                Ty::Function(FnPointer {
+                    num_args: substs.len() - 1,
+                    sig: FnSig { variadic: *is_varargs },
+                    substs,
+                })
             }
             TypeRef::DynTrait(bounds) => {
                 let self_ty = Ty::Bound(BoundVar::new(DebruijnIndex::INNERMOST, 0));
@@ -1010,7 +1014,7 @@ fn fn_sig_for_fn(db: &dyn HirDatabase, def: FunctionId) -> PolyFnSig {
     let ret = Ty::from_hir(&ctx_ret, &data.ret_type);
     let generics = generics(db.upcast(), def.into());
     let num_binders = generics.len();
-    Binders::new(num_binders, FnSig::from_params_and_return(params, ret, data.is_varargs))
+    Binders::new(num_binders, CallableSig::from_params_and_return(params, ret, data.is_varargs))
 }
 
 /// Build the declared type of a function. This should not need to look at the
@@ -1050,7 +1054,7 @@ fn fn_sig_for_struct_constructor(db: &dyn HirDatabase, def: StructId) -> PolyFnS
     let params =
         fields.iter().map(|(_, field)| Ty::from_hir(&ctx, &field.type_ref)).collect::<Vec<_>>();
     let ret = type_for_adt(db, def.into());
-    Binders::new(ret.num_binders, FnSig::from_params_and_return(params, ret.value, false))
+    Binders::new(ret.num_binders, CallableSig::from_params_and_return(params, ret.value, false))
 }
 
 /// Build the type of a tuple struct constructor.
@@ -1074,7 +1078,7 @@ fn fn_sig_for_enum_variant_constructor(db: &dyn HirDatabase, def: EnumVariantId)
     let params =
         fields.iter().map(|(_, field)| Ty::from_hir(&ctx, &field.type_ref)).collect::<Vec<_>>();
     let ret = type_for_adt(db, def.parent.into());
-    Binders::new(ret.num_binders, FnSig::from_params_and_return(params, ret.value, false))
+    Binders::new(ret.num_binders, CallableSig::from_params_and_return(params, ret.value, false))
 }
 
 /// Build the type of a tuple enum variant constructor.
diff --git a/crates/hir_ty/src/method_resolution.rs b/crates/hir_ty/src/method_resolution.rs
index ff8ce5599..c8a0ad5f1 100644
--- a/crates/hir_ty/src/method_resolution.rs
+++ b/crates/hir_ty/src/method_resolution.rs
@@ -18,8 +18,8 @@ use crate::{
     db::HirDatabase,
     primitive::{self, FloatTy, IntTy, UintTy},
     utils::all_super_traits,
-    Canonical, DebruijnIndex, InEnvironment, Scalar, Substs, TraitEnvironment, TraitRef, Ty,
-    TyKind, TypeWalk,
+    Canonical, DebruijnIndex, FnPointer, FnSig, InEnvironment, Scalar, Substs, TraitEnvironment,
+    TraitRef, Ty, TyKind, TypeWalk,
 };
 
 /// This is used as a key for indexing impls.
@@ -35,7 +35,7 @@ pub enum TyFingerprint {
     Dyn(TraitId),
     Tuple(usize),
     ForeignType(TypeAliasId),
-    FnPtr { num_args: u16, is_varargs: bool },
+    FnPtr(usize, FnSig),
 }
 
 impl TyFingerprint {
@@ -53,9 +53,7 @@ impl TyFingerprint {
             &Ty::Tuple(cardinality, _) => TyFingerprint::Tuple(cardinality),
             &Ty::RawPtr(mutability, ..) => TyFingerprint::RawPtr(mutability),
             &Ty::ForeignType(alias_id, ..) => TyFingerprint::ForeignType(alias_id),
-            &Ty::FnPtr { num_args, is_varargs, .. } => {
-                TyFingerprint::FnPtr { num_args, is_varargs }
-            }
+            &Ty::Function(FnPointer { num_args, sig, .. }) => TyFingerprint::FnPtr(num_args, sig),
             Ty::Dyn(_) => ty.dyn_trait().map(|trait_| TyFingerprint::Dyn(trait_))?,
             _ => return None,
         };
diff --git a/crates/hir_ty/src/traits/chalk.rs b/crates/hir_ty/src/traits/chalk.rs
index c53e327da..3f5f5091f 100644
--- a/crates/hir_ty/src/traits/chalk.rs
+++ b/crates/hir_ty/src/traits/chalk.rs
@@ -19,7 +19,7 @@ use crate::{
     display::HirDisplay,
     method_resolution::{TyFingerprint, ALL_FLOAT_FPS, ALL_INT_FPS},
     utils::generics,
-    BoundVar, CallableDefId, DebruijnIndex, FnSig, GenericPredicate, ProjectionPredicate,
+    BoundVar, CallableDefId, CallableSig, DebruijnIndex, GenericPredicate, ProjectionPredicate,
     ProjectionTy, Substs, TraitRef, Ty,
 };
 use mapping::{
@@ -286,9 +286,8 @@ impl<'a> chalk_solve::RustIrDatabase<Interner> for ChalkContext<'a> {
     ) -> chalk_ir::Binders<rust_ir::FnDefInputsAndOutputDatum<Interner>> {
         let sig_ty: Ty =
             from_chalk(self.db, substs.at(&Interner, 0).assert_ty_ref(&Interner).clone());
-        let sig = FnSig::from_fn_ptr_substs(
+        let sig = CallableSig::from_substs(
             &sig_ty.substs().expect("first closure param should be fn ptr"),
-            false,
         );
         let io = rust_ir::FnDefInputsAndOutputDatum {
             argument_types: sig.params().iter().map(|ty| ty.clone().to_chalk(self.db)).collect(),
diff --git a/crates/hir_ty/src/traits/chalk/mapping.rs b/crates/hir_ty/src/traits/chalk/mapping.rs
index c17c19638..60d74e21a 100644
--- a/crates/hir_ty/src/traits/chalk/mapping.rs
+++ b/crates/hir_ty/src/traits/chalk/mapping.rs
@@ -16,8 +16,8 @@ use crate::{
     db::HirDatabase,
     primitive::UintTy,
     traits::{Canonical, Obligation},
-    CallableDefId, GenericPredicate, InEnvironment, OpaqueTy, OpaqueTyId, ProjectionPredicate,
-    ProjectionTy, Scalar, Substs, TraitEnvironment, TraitRef, Ty, TyKind,
+    CallableDefId, FnPointer, FnSig, GenericPredicate, InEnvironment, OpaqueTy, OpaqueTyId,
+    ProjectionPredicate, ProjectionTy, Scalar, Substs, TraitEnvironment, TraitRef, Ty, TyKind,
 };
 
 use super::interner::*;
@@ -29,15 +29,11 @@ impl ToChalk for Ty {
         match self {
             Ty::Ref(m, parameters) => ref_to_chalk(db, m, parameters),
             Ty::Array(parameters) => array_to_chalk(db, parameters),
-            Ty::FnPtr { num_args: _, is_varargs, substs } => {
+            Ty::Function(FnPointer { sig: FnSig { variadic }, substs, .. }) => {
                 let substitution = chalk_ir::FnSubst(substs.to_chalk(db).shifted_in(&Interner));
                 chalk_ir::TyKind::Function(chalk_ir::FnPointer {
                     num_binders: 0,
-                    sig: chalk_ir::FnSig {
-                        abi: (),
-                        safety: chalk_ir::Safety::Safe,
-                        variadic: is_varargs,
-                    },
+                    sig: chalk_ir::FnSig { abi: (), safety: chalk_ir::Safety::Safe, variadic },
                     substitution,
                 })
                 .intern(&Interner)
@@ -82,7 +78,7 @@ impl ToChalk for Ty {
             }
             Ty::Never => chalk_ir::TyKind::Never.intern(&Interner),
 
-            Ty::Closure { def, expr, substs } => {
+            Ty::Closure(def, expr, substs) => {
                 let closure_id = db.intern_closure((def, expr));
                 let substitution = substs.to_chalk(db);
                 chalk_ir::TyKind::Closure(closure_id.into(), substitution).intern(&Interner)
@@ -164,15 +160,15 @@ impl ToChalk for Ty {
                 ..
             }) => {
                 assert_eq!(num_binders, 0);
-                let parameters: Substs = from_chalk(
+                let substs: Substs = from_chalk(
                     db,
                     substitution.0.shifted_out(&Interner).expect("fn ptr should have no binders"),
                 );
-                Ty::FnPtr {
-                    num_args: (parameters.len() - 1) as u16,
-                    is_varargs: variadic,
-                    substs: parameters,
-                }
+                Ty::Function(FnPointer {
+                    num_args: (substs.len() - 1),
+                    sig: FnSig { variadic },
+                    substs,
+                })
             }
             chalk_ir::TyKind::BoundVar(idx) => Ty::Bound(idx),
             chalk_ir::TyKind::InferenceVar(_iv, _kind) => Ty::Unknown,
@@ -218,7 +214,7 @@ impl ToChalk for Ty {
             chalk_ir::TyKind::Closure(id, subst) => {
                 let id: crate::db::ClosureId = id.into();
                 let (def, expr) = db.lookup_intern_closure(id);
-                Ty::Closure { def, expr, substs: from_chalk(db, subst) }
+                Ty::Closure(def, expr, from_chalk(db, subst))
             }
 
             chalk_ir::TyKind::Foreign(foreign_def_id) => {