Merge #2398

2398: WIP: introduce hir::Type r=matklad a=matklad

This introduces `hir::Type` wrapper over `hir::Ty`, with two purposes:

* bind `Ty` and it's corresponding environment
  * Am I correct that `Ty` without an env doesn't make much sense, because the meaning of type parameters is unclear
  * Am I correct that we can safely re-use the same environment for all types derived from the given type? 
* hide representation defails of `Ty`. Specifically, I want to change `Ty::Adt` to use `hir_def::AdtId` instead of `hir::Adt`, but IDE doesn't know about underlying IDs. More generally, I feel like IDE shouldn't know that `Ty` is enum.

@flodiebold what do you think about this?

Co-authored-by: Aleksey Kladov <[email protected]>

3 files changed, 185 insertions, 29 deletions

diff --git a/crates/ra_hir/src/code_model.rs b/crates/ra_hir/src/code_model.rs
index f7fc80d4e..a7bba85e1 100644
--- a/crates/ra_hir/src/code_model.rs
+++ b/crates/ra_hir/src/code_model.rs
@@ -10,9 +10,9 @@ use hir_def::{
     docs::Documentation,
     per_ns::PerNs,
     resolver::{HasResolver, TypeNs},
-    type_ref::TypeRef,
-    AstItemDef, ConstId, ContainerId, EnumId, FunctionId, GenericDefId, HasModule, ImplId,
-    LocalEnumVariantId, LocalImportId, LocalModuleId, LocalStructFieldId, Lookup, ModuleId,
+    type_ref::{Mutability, TypeRef},
+    AstItemDef, ConstId, ContainerId, DefWithBodyId, EnumId, FunctionId, GenericDefId, HasModule,
+    ImplId, LocalEnumVariantId, LocalImportId, LocalModuleId, LocalStructFieldId, Lookup, ModuleId,
     StaticId, StructId, TraitId, TypeAliasId, UnionId,
 };
 use hir_expand::{
@@ -26,8 +26,12 @@ use ra_syntax::{ast, AstNode, SyntaxNode};
 use crate::{
     db::{DefDatabase, HirDatabase},
     expr::{BindingAnnotation, Body, BodySourceMap, ExprValidator, Pat, PatId},
-    ty::{InferenceResult, Namespace, TraitRef},
-    Either, Name, Source, Ty,
+    ty::display::HirFormatter,
+    ty::{
+        self, InEnvironment, InferenceResult, Namespace, TraitEnvironment, TraitRef, Ty, TypeCtor,
+        TypeWalk,
+    },
+    CallableDef, Either, HirDisplay, Name, Source,
 };
 
 /// hir::Crate describes a single crate. It's the main interface with which
@@ -469,6 +473,10 @@ pub enum Adt {
 impl_froms!(Adt: Struct, Union, Enum);
 
 impl Adt {
+    pub fn has_non_default_type_params(self, db: &impl HirDatabase) -> bool {
+        let subst = db.generic_defaults(self.into());
+        subst.iter().any(|ty| ty == &Ty::Unknown)
+    }
     pub fn ty(self, db: &impl HirDatabase) -> Ty {
         match self {
             Adt::Struct(it) => it.ty(db),
@@ -777,6 +785,11 @@ pub struct TypeAlias {
 }
 
 impl TypeAlias {
+    pub fn has_non_default_type_params(self, db: &impl HirDatabase) -> bool {
+        let subst = db.generic_defaults(self.id.into());
+        subst.iter().any(|ty| ty == &Ty::Unknown)
+    }
+
     pub fn module(self, db: &impl DefDatabase) -> Module {
         Module { id: self.id.lookup(db).module(db) }
     }
@@ -927,9 +940,14 @@ impl Local {
         self.parent.module(db)
     }
 
-    pub fn ty(self, db: &impl HirDatabase) -> Ty {
+    pub fn ty(self, db: &impl HirDatabase) -> Type {
         let infer = db.infer(self.parent);
-        infer[self.pat_id].clone()
+        let ty = infer[self.pat_id].clone();
+        let def = DefWithBodyId::from(self.parent);
+        let resolver = def.resolver(db);
+        let krate = def.module(db).krate;
+        let environment = TraitEnvironment::lower(db, &resolver);
+        Type { krate, ty: InEnvironment { value: ty, environment } }
     }
 
     pub fn source(self, db: &impl HirDatabase) -> Source<Either<ast::BindPat, ast::SelfParam>> {
@@ -986,6 +1004,140 @@ impl ImplBlock {
     }
 }
 
+#[derive(Clone, PartialEq, Eq)]
+pub struct Type {
+    pub(crate) krate: CrateId,
+    pub(crate) ty: InEnvironment<Ty>,
+}
+
+impl Type {
+    pub fn is_bool(&self) -> bool {
+        match &self.ty.value {
+            Ty::Apply(a_ty) => match a_ty.ctor {
+                TypeCtor::Bool => true,
+                _ => false,
+            },
+            _ => false,
+        }
+    }
+
+    pub fn is_mutable_reference(&self) -> bool {
+        match &self.ty.value {
+            Ty::Apply(a_ty) => match a_ty.ctor {
+                TypeCtor::Ref(Mutability::Mut) => true,
+                _ => false,
+            },
+            _ => false,
+        }
+    }
+
+    pub fn is_unknown(&self) -> bool {
+        match &self.ty.value {
+            Ty::Unknown => true,
+            _ => false,
+        }
+    }
+
+    // FIXME: this method is broken, as it doesn't take closures into account.
+    pub fn as_callable(&self) -> Option<CallableDef> {
+        Some(self.ty.value.as_callable()?.0)
+    }
+
+    pub fn contains_unknown(&self) -> bool {
+        return go(&self.ty.value);
+
+        fn go(ty: &Ty) -> bool {
+            match ty {
+                Ty::Unknown => true,
+                Ty::Apply(a_ty) => a_ty.parameters.iter().any(go),
+                _ => false,
+            }
+        }
+    }
+
+    pub fn fields(&self, db: &impl HirDatabase) -> Vec<(StructField, Type)> {
+        let mut res = Vec::new();
+        if let Ty::Apply(a_ty) = &self.ty.value {
+            match a_ty.ctor {
+                ty::TypeCtor::Adt(Adt::Struct(s)) => {
+                    for field in s.fields(db) {
+                        let ty = field.ty(db).subst(&a_ty.parameters);
+                        res.push((field, self.derived(ty)));
+                    }
+                }
+                _ => {}
+            }
+        };
+        res
+    }
+
+    pub fn tuple_fields(&self, _db: &impl HirDatabase) -> Vec<Type> {
+        let mut res = Vec::new();
+        if let Ty::Apply(a_ty) = &self.ty.value {
+            match a_ty.ctor {
+                ty::TypeCtor::Tuple { .. } => {
+                    for ty in a_ty.parameters.iter() {
+                        let ty = ty.clone().subst(&a_ty.parameters);
+                        res.push(self.derived(ty));
+                    }
+                }
+                _ => {}
+            }
+        };
+        res
+    }
+
+    pub fn variant_fields(
+        &self,
+        db: &impl HirDatabase,
+        def: VariantDef,
+    ) -> Vec<(StructField, Type)> {
+        // FIXME: check that ty and def match
+        match &self.ty.value {
+            Ty::Apply(a_ty) => def
+                .fields(db)
+                .into_iter()
+                .map(|it| (it, self.derived(it.ty(db).subst(&a_ty.parameters))))
+                .collect(),
+            _ => Vec::new(),
+        }
+    }
+
+    pub fn autoderef<'a>(&'a self, db: &'a impl HirDatabase) -> impl Iterator<Item = Type> + 'a {
+        // There should be no inference vars in types passed here
+        // FIXME check that?
+        let canonical = crate::ty::Canonical { value: self.ty.value.clone(), num_vars: 0 };
+        let environment = self.ty.environment.clone();
+        let ty = InEnvironment { value: canonical, environment: environment.clone() };
+        ty::autoderef(db, Some(self.krate), ty)
+            .map(|canonical| canonical.value)
+            .map(move |ty| self.derived(ty))
+    }
+
+    // FIXME: remove
+    pub fn into_ty(self) -> Ty {
+        self.ty.value
+    }
+
+    pub fn as_adt(&self) -> Option<Adt> {
+        let (adt, _subst) = self.ty.value.as_adt()?;
+        Some(adt)
+    }
+
+    fn derived(&self, ty: Ty) -> Type {
+        Type {
+            krate: self.krate,
+            ty: InEnvironment { value: ty, environment: self.ty.environment.clone() },
+        }
+    }
+}
+
+impl HirDisplay for Type {
+    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> std::fmt::Result {
+        self.ty.value.hir_fmt(f)
+    }
+}
+
 /// For IDE only
 pub enum ScopeDef {
     ModuleDef(ModuleDef),
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index 843ce6a88..b88e4c745 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -51,7 +51,7 @@ pub use crate::{
         src::HasSource, Adt, AssocItem, AttrDef, Const, Container, Crate, CrateDependency,
         DefWithBody, Docs, Enum, EnumVariant, FieldSource, Function, GenericDef, GenericParam,
         HasAttrs, ImplBlock, Import, Local, MacroDef, Module, ModuleDef, ModuleSource, ScopeDef,
-        Static, Struct, StructField, Trait, TypeAlias, Union, VariantDef,
+        Static, Struct, StructField, Trait, Type, TypeAlias, Union, VariantDef,
     },
     expr::ExprScopes,
     from_source::FromSource,
diff --git a/crates/ra_hir/src/source_binder.rs b/crates/ra_hir/src/source_binder.rs
index cbfeca3ab..95a94c3f0 100644
--- a/crates/ra_hir/src/source_binder.rs
+++ b/crates/ra_hir/src/source_binder.rs
@@ -28,10 +28,10 @@ use crate::{
     expr::{BodySourceMap, ExprScopes, ScopeId},
     ty::{
         method_resolution::{self, implements_trait},
-        TraitEnvironment,
+        InEnvironment, TraitEnvironment, Ty,
     },
     Adt, AssocItem, Const, DefWithBody, Either, Enum, EnumVariant, FromSource, Function,
-    GenericParam, Local, MacroDef, Name, Path, ScopeDef, Static, Struct, Trait, Ty, TypeAlias,
+    GenericParam, Local, MacroDef, Name, Path, ScopeDef, Static, Struct, Trait, Type, TypeAlias,
 };
 
 fn try_get_resolver_for_node(db: &impl HirDatabase, node: Source<&SyntaxNode>) -> Option<Resolver> {
@@ -198,14 +198,18 @@ impl SourceAnalyzer {
         self.body_source_map.as_ref()?.node_pat(src)
     }
 
-    pub fn type_of(&self, _db: &impl HirDatabase, expr: &ast::Expr) -> Option<crate::Ty> {
+    pub fn type_of(&self, db: &impl HirDatabase, expr: &ast::Expr) -> Option<Type> {
         let expr_id = self.expr_id(expr)?;
-        Some(self.infer.as_ref()?[expr_id].clone())
+        let ty = self.infer.as_ref()?[expr_id].clone();
+        let environment = TraitEnvironment::lower(db, &self.resolver);
+        Some(Type { krate: self.resolver.krate()?, ty: InEnvironment { value: ty, environment } })
     }
 
-    pub fn type_of_pat(&self, _db: &impl HirDatabase, pat: &ast::Pat) -> Option<crate::Ty> {
+    pub fn type_of_pat(&self, db: &impl HirDatabase, pat: &ast::Pat) -> Option<Type> {
         let pat_id = self.pat_id(pat)?;
-        Some(self.infer.as_ref()?[pat_id].clone())
+        let ty = self.infer.as_ref()?[pat_id].clone();
+        let environment = TraitEnvironment::lower(db, &self.resolver);
+        Some(Type { krate: self.resolver.krate()?, ty: InEnvironment { value: ty, environment } })
     }
 
     pub fn resolve_method_call(&self, call: &ast::MethodCallExpr) -> Option<Function> {
@@ -361,14 +365,14 @@ impl SourceAnalyzer {
     pub fn iterate_method_candidates<T>(
         &self,
         db: &impl HirDatabase,
-        ty: Ty,
+        ty: &Type,
         name: Option<&Name>,
         mut callback: impl FnMut(&Ty, Function) -> Option<T>,
     ) -> Option<T> {
         // There should be no inference vars in types passed here
         // FIXME check that?
         // FIXME replace Unknown by bound vars here
-        let canonical = crate::ty::Canonical { value: ty, num_vars: 0 };
+        let canonical = crate::ty::Canonical { value: ty.ty.value.clone(), num_vars: 0 };
         method_resolution::iterate_method_candidates(
             &canonical,
             db,
@@ -403,19 +407,19 @@ impl SourceAnalyzer {
         )
     }
 
-    pub fn autoderef<'a>(
-        &'a self,
-        db: &'a impl HirDatabase,
-        ty: Ty,
-    ) -> impl Iterator<Item = Ty> + 'a {
-        // There should be no inference vars in types passed here
-        // FIXME check that?
-        let canonical = crate::ty::Canonical { value: ty, num_vars: 0 };
-        let krate = self.resolver.krate();
-        let environment = TraitEnvironment::lower(db, &self.resolver);
-        let ty = crate::ty::InEnvironment { value: canonical, environment };
-        crate::ty::autoderef(db, krate, ty).map(|canonical| canonical.value)
-    }
+    // pub fn autoderef<'a>(
+    //     &'a self,
+    //     db: &'a impl HirDatabase,
+    //     ty: Ty,
+    // ) -> impl Iterator<Item = Ty> + 'a {
+    //     // There should be no inference vars in types passed here
+    //     // FIXME check that?
+    //     let canonical = crate::ty::Canonical { value: ty, num_vars: 0 };
+    //     let krate = self.resolver.krate();
+    //     let environment = TraitEnvironment::lower(db, &self.resolver);
+    //     let ty = crate::ty::InEnvironment { value: canonical, environment };
+    //     crate::ty::autoderef(db, krate, ty).map(|canonical| canonical.value)
+    // }
 
     /// Checks that particular type `ty` implements `std::future::Future`.
     /// This function is used in `.await` syntax completion.