Merge #897

897: Add basic const/static type inference r=flodiebold a=vipentti

This adds basic const/static type inference discussed in #887.

Currently the inference does not work for const/static declared inside a block. In addition the inference does not work inside the bodies of const/static.

Co-authored-by: Ville Penttinen <villem.penttinen@gmail.com>

crates/ra_hir/src/code_model_api.rs

@@ -554,11 +554,26 @@ impl Const {
         self.id.module(db)
     }
 
+    pub fn signature(&self, db: &impl HirDatabase) -> Arc<ConstSignature> {
+        db.const_signature(*self)
+    }
+
     /// The containing impl block, if this is a method.
     pub fn impl_block(&self, db: &impl PersistentHirDatabase) -> Option<ImplBlock> {
         let module_impls = db.impls_in_module(self.module(db));
         ImplBlock::containing(module_impls, (*self).into())
     }
+
+    // TODO: move to a more general type for 'body-having' items
+    /// Builds a resolver for code inside this item.
+    pub fn resolver(&self, db: &impl HirDatabase) -> Resolver {
+        // take the outer scope...
+        let r = self
+            .impl_block(db)
+            .map(|ib| ib.resolver(db))
+            .unwrap_or_else(|| self.module(db).resolver(db));
+        r
+    }
 }
 
 impl Docs for Const {
@@ -567,6 +582,23 @@ impl Docs for Const {
     }
 }
 
+/// The declared signature of a const.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct ConstSignature {
+    pub(crate) name: Name,
+    pub(crate) type_ref: TypeRef,
+}
+
+impl ConstSignature {
+    pub fn name(&self) -> &Name {
+        &self.name
+    }
+
+    pub fn type_ref(&self) -> &TypeRef {
+        &self.type_ref
+    }
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct Static {
     pub(crate) id: StaticId,
@@ -580,6 +612,16 @@ impl Static {
     pub fn module(&self, db: &impl PersistentHirDatabase) -> Module {
         self.id.module(db)
     }
+
+    pub fn signature(&self, db: &impl HirDatabase) -> Arc<ConstSignature> {
+        db.static_signature(*self)
+    }
+
+    /// Builds a resolver for code inside this item.
+    pub fn resolver(&self, db: &impl HirDatabase) -> Resolver {
+        // take the outer scope...
+        self.module(db).resolver(db)
+    }
 }
 
 impl Docs for Static {

crates/ra_hir/src/code_model_impl.rs

@@ -1,3 +1,4 @@
 mod krate; // `crate` is invalid ident :(
+mod konst; // `const` is invalid ident :(
 mod module;
 pub(crate) mod function;

crates/ra_hir/src/code_model_impl/konst.rs

@@ -0,0 +1,37 @@
+use std::sync::Arc;
+
+use ra_syntax::ast::{self, NameOwner};
+
+use crate::{
+    Name, AsName, Const, ConstSignature, Static,
+    type_ref::{TypeRef},
+    PersistentHirDatabase,
+};
+
+fn const_signature_for<N: NameOwner>(
+    node: &N,
+    type_ref: Option<&ast::TypeRef>,
+) -> Arc<ConstSignature> {
+    let name = node.name().map(|n| n.as_name()).unwrap_or_else(Name::missing);
+    let type_ref = TypeRef::from_ast_opt(type_ref);
+    let sig = ConstSignature { name, type_ref };
+    Arc::new(sig)
+}
+
+impl ConstSignature {
+    pub(crate) fn const_signature_query(
+        db: &impl PersistentHirDatabase,
+        konst: Const,
+    ) -> Arc<ConstSignature> {
+        let (_, node) = konst.source(db);
+        const_signature_for(&*node, node.type_ref())
+    }
+
+    pub(crate) fn static_signature_query(
+        db: &impl PersistentHirDatabase,
+        konst: Static,
+    ) -> Arc<ConstSignature> {
+        let (_, node) = konst.source(db);
+        const_signature_for(&*node, node.type_ref())
+    }
+}

crates/ra_hir/src/db.rs

@@ -8,6 +8,7 @@ use crate::{
     SourceFileItems, SourceItemId, Crate, Module, HirInterner,
     Function, FnSignature, ExprScopes, TypeAlias,
     Struct, Enum, StructField,
+    Const, ConstSignature, Static,
     macros::MacroExpansion,
     module_tree::ModuleTree,
     nameres::{ItemMap, lower::{LoweredModule, ImportSourceMap}},
@@ -82,6 +83,12 @@ pub trait PersistentHirDatabase: SourceDatabase + AsRef<HirInterner> {
 
     #[salsa::invoke(crate::type_alias::type_alias_ref_query)]
     fn type_alias_ref(&self, typ: TypeAlias) -> Arc<TypeRef>;
+
+    #[salsa::invoke(crate::ConstSignature::const_signature_query)]
+    fn const_signature(&self, konst: Const) -> Arc<ConstSignature>;
+
+    #[salsa::invoke(crate::ConstSignature::static_signature_query)]
+    fn static_signature(&self, konst: Static) -> Arc<ConstSignature>;
 }
 
 #[salsa::query_group(HirDatabaseStorage)]

crates/ra_hir/src/lib.rs

@@ -71,6 +71,6 @@ pub use self::code_model_api::{
     Struct, Enum, EnumVariant,
     Function, FnSignature,
     StructField, FieldSource,
-    Static, Const,
+    Static, Const, ConstSignature,
     Trait, TypeAlias,
 };

crates/ra_hir/src/ty/infer.rs

@@ -393,17 +393,22 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
             // Attempt to find an impl_item for the type which has a name matching
             // the current segment
             log::debug!("looking for path segment: {:?}", segment);
-            let item = ty.iterate_impl_items(self.db, |item| match item {
+            let item: crate::ModuleDef = ty.iterate_impl_items(self.db, |item| match item {
                 crate::ImplItem::Method(func) => {
                     let sig = func.signature(self.db);
                     if segment.name == *sig.name() {
-                        return Some(func);
+                        return Some(func.into());
                     }
                     None
                 }
 
-                // TODO: Resolve associated const
+                crate::ImplItem::Const(konst) => {
-                crate::ImplItem::Const(_) => None,
+                    let sig = konst.signature(self.db);
+                    if segment.name == *sig.name() {
+                        return Some(konst.into());
+                    }
+                    None
+                }
 
                 // TODO: Resolve associated types
                 crate::ImplItem::TypeAlias(_) => None,
@@ -477,9 +482,11 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 let ty = self.insert_type_vars(ty.apply_substs(substs));
                 (ty, Some(var.into()))
             }
-            TypableDef::TypeAlias(_) | TypableDef::Function(_) | TypableDef::Enum(_) => {
+            TypableDef::TypeAlias(_)
-                (Ty::Unknown, None)
+            | TypableDef::Function(_)
-            }
+            | TypableDef::Enum(_)
+            | TypableDef::Const(_)
+            | TypableDef::Static(_) => (Ty::Unknown, None),
         }
     }
 

crates/ra_hir/src/ty/lower.rs

@@ -11,6 +11,7 @@ use std::sync::Arc;
 use crate::{
     Function, Struct, StructField, Enum, EnumVariant, Path, Name,
     ModuleDef, TypeAlias,
+    Const, Static,
     HirDatabase,
     type_ref::TypeRef,
     name::KnownName,
@@ -125,6 +126,7 @@ impl Ty {
             TypableDef::Enum(e) => e.generic_params(db),
             TypableDef::EnumVariant(var) => var.parent_enum(db).generic_params(db),
             TypableDef::TypeAlias(t) => t.generic_params(db),
+            TypableDef::Const(_) | TypableDef::Static(_) => GenericParams::default().into(),
         };
         let parent_param_count = def_generics.count_parent_params();
         substs.extend((0..parent_param_count).map(|_| Ty::Unknown));
@@ -163,6 +165,8 @@ impl Ty {
             TypableDef::Function(_)
             | TypableDef::Struct(_)
             | TypableDef::Enum(_)
+            | TypableDef::Const(_)
+            | TypableDef::Static(_)
             | TypableDef::TypeAlias(_) => last,
             TypableDef::EnumVariant(_) => {
                 // the generic args for an enum variant may be either specified
@@ -197,12 +201,16 @@ pub(crate) fn type_for_def(db: &impl HirDatabase, def: TypableDef, ns: Namespace
         (TypableDef::Enum(e), Namespace::Types) => type_for_enum(db, e),
         (TypableDef::EnumVariant(v), Namespace::Values) => type_for_enum_variant_constructor(db, v),
         (TypableDef::TypeAlias(t), Namespace::Types) => type_for_type_alias(db, t),
+        (TypableDef::Const(c), Namespace::Values) => type_for_const(db, c),
+        (TypableDef::Static(c), Namespace::Values) => type_for_static(db, c),
 
         // 'error' cases:
         (TypableDef::Function(_), Namespace::Types) => Ty::Unknown,
         (TypableDef::Enum(_), Namespace::Values) => Ty::Unknown,
         (TypableDef::EnumVariant(_), Namespace::Types) => Ty::Unknown,
         (TypableDef::TypeAlias(_), Namespace::Values) => Ty::Unknown,
+        (TypableDef::Const(_), Namespace::Types) => Ty::Unknown,
+        (TypableDef::Static(_), Namespace::Types) => Ty::Unknown,
     }
 }
 
@@ -233,6 +241,22 @@ fn type_for_fn(db: &impl HirDatabase, def: Function) -> Ty {
     Ty::FnDef { def: def.into(), sig, name, substs }
 }
 
+/// Build the declared type of a const.
+fn type_for_const(db: &impl HirDatabase, def: Const) -> Ty {
+    let signature = def.signature(db);
+    let resolver = def.resolver(db);
+
+    Ty::from_hir(db, &resolver, signature.type_ref())
+}
+
+/// Build the declared type of a static.
+fn type_for_static(db: &impl HirDatabase, def: Static) -> Ty {
+    let signature = def.signature(db);
+    let resolver = def.resolver(db);
+
+    Ty::from_hir(db, &resolver, signature.type_ref())
+}
+
 /// Build the type of a tuple struct constructor.
 fn type_for_struct_constructor(db: &impl HirDatabase, def: Struct) -> Ty {
     let var_data = def.variant_data(db);
@@ -318,8 +342,10 @@ pub enum TypableDef {
     Enum(Enum),
     EnumVariant(EnumVariant),
     TypeAlias(TypeAlias),
+    Const(Const),
+    Static(Static),
 }
-impl_froms!(TypableDef: Function, Struct, Enum, EnumVariant, TypeAlias);
+impl_froms!(TypableDef: Function, Struct, Enum, EnumVariant, TypeAlias, Const, Static);
 
 impl From<ModuleDef> for Option<TypableDef> {
     fn from(def: ModuleDef) -> Option<TypableDef> {
@@ -329,10 +355,9 @@ impl From<ModuleDef> for Option<TypableDef> {
             ModuleDef::Enum(e) => e.into(),
             ModuleDef::EnumVariant(v) => v.into(),
             ModuleDef::TypeAlias(t) => t.into(),
-            ModuleDef::Const(_)
+            ModuleDef::Const(v) => v.into(),
-            | ModuleDef::Static(_)
+            ModuleDef::Static(v) => v.into(),
-            | ModuleDef::Module(_)
+            ModuleDef::Module(_) | ModuleDef::Trait(_) => return None,
-            | ModuleDef::Trait(_) => return None,
         };
         Some(res)
     }

crates/ra_hir/src/ty/snapshots/tests__infer_associated_const.snap

@@ -1,14 +1,14 @@
 ---
-created: "2019-02-21T21:51:46.497925200Z"
+created: "2019-02-25T08:36:33.885804400Z"
 creator: insta@0.6.3
 source: crates/ra_hir/src/ty/tests.rs
 expression: "&result"
 ---
 [227; 305) '{     ...:ID; }': ()
-[237; 238) 'x': [unknown]
+[237; 238) 'x': u32
-[241; 252) 'Struct::FOO': [unknown]
+[241; 252) 'Struct::FOO': u32
-[262; 263) 'y': [unknown]
+[262; 263) 'y': u32
-[266; 275) 'Enum::BAR': [unknown]
+[266; 275) 'Enum::BAR': u32
-[285; 286) 'z': [unknown]
+[285; 286) 'z': u32
-[289; 302) 'TraitTest::ID': [unknown]
+[289; 302) 'TraitTest::ID': u32
 

crates/ra_hir/src/ty/snapshots/tests__infer_const.snap

@@ -0,0 +1,14 @@
+---
+created: "2019-02-25T07:26:34.115351100Z"
+creator: insta@0.6.3
+source: crates/ra_hir/src/ty/tests.rs
+expression: "&result"
+---
+[95; 213) '{     ...NST; }': ()
+[138; 139) 'x': [unknown]
+[142; 153) 'LOCAL_CONST': [unknown]
+[163; 164) 'z': u32
+[167; 179) 'GLOBAL_CONST': u32
+[189; 191) 'id': u32
+[194; 210) 'Foo::A..._CONST': u32
+

crates/ra_hir/src/ty/snapshots/tests__infer_static.snap

@@ -0,0 +1,16 @@
+---
+created: "2019-02-25T08:20:17.807316Z"
+creator: insta@0.6.3
+source: crates/ra_hir/src/ty/tests.rs
+expression: "&result"
+---
+[85; 280) '{     ...MUT; }': ()
+[173; 174) 'x': [unknown]
+[177; 189) 'LOCAL_STATIC': [unknown]
+[199; 200) 'y': [unknown]
+[203; 219) 'LOCAL_...IC_MUT': [unknown]
+[229; 230) 'z': u32
+[233; 246) 'GLOBAL_STATIC': u32
+[256; 257) 'w': u32
+[260; 277) 'GLOBAL...IC_MUT': u32
+

crates/ra_hir/src/ty/tests.rs

@@ -1006,6 +1006,43 @@ mod foo {
     assert_eq!("i128", type_at_pos(&db, pos));
 }
 
+#[test]
+fn infer_const() {
+    check_inference(
+        "infer_const",
+        r#"
+struct Foo;
+impl Foo { const ASSOC_CONST: u32 = 0; }
+const GLOBAL_CONST: u32 = 101;
+fn test() {
+    const LOCAL_CONST: u32 = 99;
+    let x = LOCAL_CONST;
+    let z = GLOBAL_CONST;
+    let id = Foo::ASSOC_CONST;
+}
+"#,
+    );
+}
+
+#[test]
+fn infer_static() {
+    check_inference(
+        "infer_static",
+        r#"
+static GLOBAL_STATIC: u32 = 101;
+static mut GLOBAL_STATIC_MUT: u32 = 101;
+fn test() {
+    static LOCAL_STATIC: u32 = 99;
+    static mut LOCAL_STATIC_MUT: u32 = 99;
+    let x = LOCAL_STATIC;
+    let y = LOCAL_STATIC_MUT;
+    let z = GLOBAL_STATIC;
+    let w = GLOBAL_STATIC_MUT;
+}
+"#,
+    );
+}
+
 fn type_at_pos(db: &MockDatabase, pos: FilePosition) -> String {
     let func = source_binder::function_from_position(db, pos).unwrap();
     let body_syntax_mapping = func.body_syntax_mapping(db);