Use Chalk's built-in representation of function item types

crates/ra_hir_ty/src/db.rs

@@ -76,6 +76,8 @@ pub trait HirDatabase: DefDatabase + Upcast<dyn DefDatabase> {
     #[salsa::interned]
     fn intern_type_ctor(&self, type_ctor: TypeCtor) -> crate::TypeCtorId;
     #[salsa::interned]
+    fn intern_callable_def(&self, callable_def: CallableDef) -> crate::CallableDefId;
+    #[salsa::interned]
     fn intern_type_param_id(&self, param_id: TypeParamId) -> GlobalTypeParamId;
     #[salsa::interned]
     fn intern_chalk_impl(&self, impl_: Impl) -> crate::traits::GlobalImplId;
@@ -94,6 +96,9 @@ pub trait HirDatabase: DefDatabase + Upcast<dyn DefDatabase> {
     #[salsa::invoke(crate::traits::chalk::impl_datum_query)]
     fn impl_datum(&self, krate: CrateId, impl_id: chalk::ImplId) -> Arc<chalk::ImplDatum>;
 
+    #[salsa::invoke(crate::traits::chalk::fn_def_datum_query)]
+    fn fn_def_datum(&self, krate: CrateId, fn_def_id: chalk::FnDefId) -> Arc<chalk::FnDefDatum>;
+
     #[salsa::invoke(crate::traits::chalk::associated_ty_value_query)]
     fn associated_ty_value(
         &self,

crates/ra_hir_ty/src/lib.rs

@@ -159,6 +159,12 @@ pub enum TypeCtor {
 pub struct TypeCtorId(salsa::InternId);
 impl_intern_key!(TypeCtorId);
 
+/// This exists just for Chalk, because Chalk just has a single `FnDefId` where
+/// we have different IDs for struct and enum variant constructors.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Ord, PartialOrd)]
+pub struct CallableDefId(salsa::InternId);
+impl_intern_key!(CallableDefId);
+
 impl TypeCtor {
     pub fn num_ty_params(self, db: &dyn HirDatabase) -> usize {
         match self {

crates/ra_hir_ty/src/tests/traits.rs

@@ -2643,6 +2643,48 @@ fn test() {
     );
 }
 
+#[test]
+fn builtin_fn_def_copy() {
+    assert_snapshot!(
+        infer_with_mismatches(r#"
+#[lang = "copy"]
+trait Copy {}
+
+fn foo() {}
+fn bar<T: Copy>(T) -> T {}
+struct Struct(usize);
+enum Enum { Variant(usize) }
+
+trait Test { fn test(&self) -> bool; }
+impl<T: Copy> Test for T {}
+
+fn test() {
+    foo.test();
+    bar.test();
+    Struct.test();
+    Enum::Variant.test();
+}
+"#, true),
+        // wrong result, because the built-in Copy impl for fn defs doesn't exist in Chalk yet
+        @r###"
+    42..44 '{}': ()
+    61..62 'T': {unknown}
+    69..71 '{}': ()
+    69..71: expected T, got ()
+    146..150 'self': &Self
+    202..282 '{     ...t(); }': ()
+    208..211 'foo': fn foo()
+    208..218 'foo.test()': {unknown}
+    224..227 'bar': fn bar<{unknown}>({unknown}) -> {unknown}
+    224..234 'bar.test()': {unknown}
+    240..246 'Struct': Struct(usize) -> Struct
+    240..253 'Struct.test()': {unknown}
+    259..272 'Enum::Variant': Variant(usize) -> Enum
+    259..279 'Enum::...test()': {unknown}
+    "###
+    );
+}
+
 #[test]
 fn builtin_sized() {
     assert_snapshot!(

crates/ra_hir_ty/src/traits/chalk.rs

@@ -14,7 +14,7 @@ use ra_db::{salsa::InternKey, CrateId};
 use super::{builtin, AssocTyValue, ChalkContext, Impl};
 use crate::{
     db::HirDatabase, display::HirDisplay, method_resolution::TyFingerprint, utils::generics,
-    DebruijnIndex, GenericPredicate, Substs, Ty, TypeCtor,
+    CallableDef, DebruijnIndex, GenericPredicate, Substs, Ty, TypeCtor,
 };
 use chalk_rust_ir::WellKnownTrait;
 use mapping::{convert_where_clauses, generic_predicate_to_inline_bound, make_binders};
@@ -54,10 +54,9 @@ impl<'a> chalk_solve::RustIrDatabase<Interner> for ChalkContext<'a> {
 
     fn fn_def_datum(
         &self,
-        _fn_def_id: chalk_ir::FnDefId<Interner>,
+        fn_def_id: chalk_ir::FnDefId<Interner>,
     ) -> Arc<chalk_rust_ir::FnDefDatum<Interner>> {
-        // We don't yet provide any FnDefs to Chalk
-        unimplemented!()
+        self.db.fn_def_datum(self.krate, fn_def_id)
     }
 
     fn impls_for_trait(
@@ -405,6 +404,26 @@ fn type_alias_associated_ty_value(
     Arc::new(value)
 }
 
+pub(crate) fn fn_def_datum_query(
+    db: &dyn HirDatabase,
+    _krate: CrateId,
+    fn_def_id: FnDefId,
+) -> Arc<FnDefDatum> {
+    let callable_def: CallableDef = from_chalk(db, fn_def_id);
+    let generic_params = generics(db.upcast(), callable_def.into());
+    let sig = db.callable_item_signature(callable_def);
+    let bound_vars = Substs::bound_vars(&generic_params, DebruijnIndex::INNERMOST);
+    let where_clauses = convert_where_clauses(db, callable_def.into(), &bound_vars);
+    let bound = chalk_rust_ir::FnDefDatumBound {
+        // Note: Chalk doesn't actually use this information yet as far as I am aware, but we provide it anyway
+        argument_types: sig.value.params().iter().map(|ty| ty.clone().to_chalk(db)).collect(),
+        return_type: sig.value.ret().clone().to_chalk(db),
+        where_clauses,
+    };
+    let datum = FnDefDatum { id: fn_def_id, binders: make_binders(bound, sig.num_binders) };
+    Arc::new(datum)
+}
+
 impl From<AdtId> for crate::TypeCtorId {
     fn from(struct_id: AdtId) -> Self {
         struct_id.0
@@ -417,6 +436,18 @@ impl From<crate::TypeCtorId> for AdtId {
     }
 }
 
+impl From<FnDefId> for crate::CallableDefId {
+    fn from(fn_def_id: FnDefId) -> Self {
+        InternKey::from_intern_id(fn_def_id.0)
+    }
+}
+
+impl From<crate::CallableDefId> for FnDefId {
+    fn from(callable_def_id: crate::CallableDefId) -> Self {
+        chalk_ir::FnDefId(callable_def_id.as_intern_id())
+    }
+}
+
 impl From<ImplId> for crate::traits::GlobalImplId {
     fn from(impl_id: ImplId) -> Self {
         InternKey::from_intern_id(impl_id.0)

crates/ra_hir_ty/src/traits/chalk/interner.rs

@@ -20,6 +20,8 @@ pub type ImplId = chalk_ir::ImplId<Interner>;
 pub type ImplDatum = chalk_rust_ir::ImplDatum<Interner>;
 pub type AssociatedTyValueId = chalk_rust_ir::AssociatedTyValueId<Interner>;
 pub type AssociatedTyValue = chalk_rust_ir::AssociatedTyValue<Interner>;
+pub type FnDefId = chalk_ir::FnDefId<Interner>;
+pub type FnDefDatum = chalk_rust_ir::FnDefDatum<Interner>;
 
 impl chalk_ir::interner::Interner for Interner {
     type InternedType = Box<chalk_ir::TyData<Self>>; // FIXME use Arc?

crates/ra_hir_ty/src/traits/chalk/mapping.rs

@@ -15,8 +15,8 @@ use crate::{
     db::HirDatabase,
     primitive::{FloatBitness, FloatTy, IntBitness, IntTy, Signedness, Uncertain},
     traits::{builtin, AssocTyValue, Canonical, Impl, Obligation},
-    ApplicationTy, GenericPredicate, InEnvironment, ProjectionPredicate, ProjectionTy, Substs,
-    TraitEnvironment, TraitRef, Ty, TypeCtor,
+    ApplicationTy, CallableDef, GenericPredicate, InEnvironment, ProjectionPredicate, ProjectionTy,
+    Substs, TraitEnvironment, TraitRef, Ty, TypeCtor,
 };
 
 use super::interner::*;
@@ -217,11 +217,14 @@ impl ToChalk for TypeCtor {
             TypeCtor::Slice => TypeName::Slice,
             TypeCtor::Ref(mutability) => TypeName::Ref(mutability.to_chalk(db)),
             TypeCtor::Str => TypeName::Str,
+            TypeCtor::FnDef(callable_def) => {
+                let id = callable_def.to_chalk(db);
+                TypeName::FnDef(id)
+            }
             TypeCtor::Int(Uncertain::Unknown)
             | TypeCtor::Float(Uncertain::Unknown)
             | TypeCtor::Adt(_)
             | TypeCtor::Array
-            | TypeCtor::FnDef(_)
             | TypeCtor::FnPtr { .. }
             | TypeCtor::Never
             | TypeCtor::Closure { .. } => {
@@ -260,7 +263,10 @@ impl ToChalk for TypeCtor {
             TypeName::Ref(mutability) => TypeCtor::Ref(from_chalk(db, mutability)),
             TypeName::Str => TypeCtor::Str,
 
-            TypeName::FnDef(_) => unreachable!(),
+            TypeName::FnDef(fn_def_id) => {
+                let callable_def = from_chalk(db, fn_def_id);
+                TypeCtor::FnDef(callable_def)
+            }
 
             TypeName::Error => {
                 // this should not be reached, since we don't represent TypeName::Error with TypeCtor
@@ -347,6 +353,18 @@ impl ToChalk for Impl {
     }
 }
 
+impl ToChalk for CallableDef {
+    type Chalk = FnDefId;
+
+    fn to_chalk(self, db: &dyn HirDatabase) -> FnDefId {
+        db.intern_callable_def(self).into()
+    }
+
+    fn from_chalk(db: &dyn HirDatabase, fn_def_id: FnDefId) -> CallableDef {
+        db.lookup_intern_callable_def(fn_def_id.into())
+    }
+}
+
 impl ToChalk for TypeAliasId {
     type Chalk = AssocTypeId;
 

crates/ra_hir_ty/src/traits/chalk/tls.rs

@@ -247,10 +247,24 @@ impl DebugContext<'_> {
 
     pub fn debug_fn_def_id(
         &self,
-        _fn_def_id: chalk_ir::FnDefId<Interner>,
+        fn_def_id: chalk_ir::FnDefId<Interner>,
         fmt: &mut fmt::Formatter<'_>,
     ) -> Result<(), fmt::Error> {
-        write!(fmt, "fn")
+        let def: CallableDef = from_chalk(self.0, fn_def_id);
+        let name = match def {
+            CallableDef::FunctionId(ff) => self.0.function_data(ff).name.clone(),
+            CallableDef::StructId(s) => self.0.struct_data(s).name.clone(),
+            CallableDef::EnumVariantId(e) => {
+                let enum_data = self.0.enum_data(e.parent);
+                enum_data.variants[e.local_id].name.clone()
+            }
+        };
+        match def {
+            CallableDef::FunctionId(_) => write!(fmt, "{{fn {}}}", name),
+            CallableDef::StructId(_) | CallableDef::EnumVariantId(_) => {
+                write!(fmt, "{{ctor {}}}", name)
+            }
+        }
     }
 
     pub fn debug_const(