Implement parameter variance inference

crates/hir-ty/src/chalk_db.rs

@@ -950,11 +950,18 @@ pub(crate) fn fn_def_datum_query(db: &dyn HirDatabase, fn_def_id: FnDefId) -> Ar
 
 pub(crate) fn fn_def_variance_query(db: &dyn HirDatabase, fn_def_id: FnDefId) -> Variances {
     let callable_def: CallableDefId = from_chalk(db, fn_def_id);
-    let generic_params =
-        generics(db.upcast(), GenericDefId::from_callable(db.upcast(), callable_def));
     Variances::from_iter(
         Interner,
-        std::iter::repeat(chalk_ir::Variance::Invariant).take(generic_params.len()),
+        db.variances_of(GenericDefId::from_callable(db.upcast(), callable_def))
+            .as_deref()
+            .unwrap_or_default()
+            .iter()
+            .map(|v| match v {
+                crate::variance::Variance::Covariant => chalk_ir::Variance::Covariant,
+                crate::variance::Variance::Invariant => chalk_ir::Variance::Invariant,
+                crate::variance::Variance::Contravariant => chalk_ir::Variance::Contravariant,
+                crate::variance::Variance::Bivariant => chalk_ir::Variance::Invariant,
+            }),
     )
 }
 
@@ -962,10 +969,14 @@ pub(crate) fn adt_variance_query(
     db: &dyn HirDatabase,
     chalk_ir::AdtId(adt_id): AdtId,
 ) -> Variances {
-    let generic_params = generics(db.upcast(), adt_id.into());
     Variances::from_iter(
         Interner,
-        std::iter::repeat(chalk_ir::Variance::Invariant).take(generic_params.len()),
+        db.variances_of(adt_id.into()).as_deref().unwrap_or_default().iter().map(|v| match v {
+            crate::variance::Variance::Covariant => chalk_ir::Variance::Covariant,
+            crate::variance::Variance::Invariant => chalk_ir::Variance::Invariant,
+            crate::variance::Variance::Contravariant => chalk_ir::Variance::Contravariant,
+            crate::variance::Variance::Bivariant => chalk_ir::Variance::Invariant,
+        }),
     )
 }
 

crates/hir-ty/src/db.rs

@@ -271,6 +271,10 @@ pub trait HirDatabase: DefDatabase + Upcast<dyn DefDatabase> {
     #[ra_salsa::invoke(chalk_db::adt_variance_query)]
     fn adt_variance(&self, adt_id: chalk_db::AdtId) -> chalk_db::Variances;
 
+    #[ra_salsa::invoke(crate::variance::variances_of)]
+    #[ra_salsa::cycle(crate::variance::variances_of_cycle)]
+    fn variances_of(&self, def: GenericDefId) -> Option<Arc<[crate::variance::Variance]>>;
+
     #[ra_salsa::invoke(chalk_db::associated_ty_value_query)]
     fn associated_ty_value(
         &self,

crates/hir-ty/src/generics.rs

@@ -132,6 +132,14 @@ impl Generics {
         self.params.len()
     }
 
+    pub(crate) fn len_self_lifetimes(&self) -> usize {
+        self.params.len_lifetimes()
+    }
+
+    pub(crate) fn has_trait_self(&self) -> bool {
+        self.params.trait_self_param().is_some()
+    }
+
     /// (parent total, self param, type params, const params, impl trait list, lifetimes)
     pub(crate) fn provenance_split(&self) -> (usize, bool, usize, usize, usize, usize) {
         let mut self_param = false;

crates/hir-ty/src/lib.rs

@@ -50,6 +50,7 @@ pub mod traits;
 mod test_db;
 #[cfg(test)]
 mod tests;
+mod variance;
 
 use std::hash::Hash;
 

crates/hir-ty/src/tests.rs

@@ -127,7 +127,15 @@ fn check_impl(ra_fixture: &str, allow_none: bool, only_types: bool, display_sour
             None => continue,
         };
         let def_map = module.def_map(&db);
-        visit_module(&db, &def_map, module.local_id, &mut |it| defs.push(it));
+        visit_module(&db, &def_map, module.local_id, &mut |it| {
+            defs.push(match it {
+                ModuleDefId::FunctionId(it) => it.into(),
+                ModuleDefId::EnumVariantId(it) => it.into(),
+                ModuleDefId::ConstId(it) => it.into(),
+                ModuleDefId::StaticId(it) => it.into(),
+                _ => return,
+            })
+        });
     }
     defs.sort_by_key(|def| match def {
         DefWithBodyId::FunctionId(it) => {
@@ -375,7 +383,15 @@ fn infer_with_mismatches(content: &str, include_mismatches: bool) -> String {
     let def_map = module.def_map(&db);
 
     let mut defs: Vec<DefWithBodyId> = Vec::new();
-    visit_module(&db, &def_map, module.local_id, &mut |it| defs.push(it));
+    visit_module(&db, &def_map, module.local_id, &mut |it| {
+        defs.push(match it {
+            ModuleDefId::FunctionId(it) => it.into(),
+            ModuleDefId::EnumVariantId(it) => it.into(),
+            ModuleDefId::ConstId(it) => it.into(),
+            ModuleDefId::StaticId(it) => it.into(),
+            _ => return,
+        })
+    });
     defs.sort_by_key(|def| match def {
         DefWithBodyId::FunctionId(it) => {
             let loc = it.lookup(&db);
@@ -405,11 +421,11 @@ fn infer_with_mismatches(content: &str, include_mismatches: bool) -> String {
     buf
 }
 
-fn visit_module(
+pub(crate) fn visit_module(
     db: &TestDB,
     crate_def_map: &DefMap,
     module_id: LocalModuleId,
-    cb: &mut dyn FnMut(DefWithBodyId),
+    cb: &mut dyn FnMut(ModuleDefId),
 ) {
     visit_scope(db, crate_def_map, &crate_def_map[module_id].scope, cb);
     for impl_id in crate_def_map[module_id].scope.impls() {
@@ -417,18 +433,18 @@ fn visit_module(
         for &item in impl_data.items.iter() {
             match item {
                 AssocItemId::FunctionId(it) => {
-                    let def = it.into();
+                    let body = db.body(it.into());
-                    cb(def);
+                    cb(it.into());
-                    let body = db.body(def);
                     visit_body(db, &body, cb);
                 }
                 AssocItemId::ConstId(it) => {
-                    let def = it.into();
+                    let body = db.body(it.into());
-                    cb(def);
+                    cb(it.into());
-                    let body = db.body(def);
                     visit_body(db, &body, cb);
                 }
-                AssocItemId::TypeAliasId(_) => (),
+                AssocItemId::TypeAliasId(it) => {
+                    cb(it.into());
+                }
             }
         }
     }
@@ -437,33 +453,27 @@ fn visit_module(
         db: &TestDB,
         crate_def_map: &DefMap,
         scope: &ItemScope,
-        cb: &mut dyn FnMut(DefWithBodyId),
+        cb: &mut dyn FnMut(ModuleDefId),
     ) {
         for decl in scope.declarations() {
+            cb(decl);
             match decl {
                 ModuleDefId::FunctionId(it) => {
-                    let def = it.into();
+                    let body = db.body(it.into());
-                    cb(def);
-                    let body = db.body(def);
                     visit_body(db, &body, cb);
                 }
                 ModuleDefId::ConstId(it) => {
-                    let def = it.into();
+                    let body = db.body(it.into());
-                    cb(def);
-                    let body = db.body(def);
                     visit_body(db, &body, cb);
                 }
                 ModuleDefId::StaticId(it) => {
-                    let def = it.into();
+                    let body = db.body(it.into());
-                    cb(def);
-                    let body = db.body(def);
                     visit_body(db, &body, cb);
                 }
                 ModuleDefId::AdtId(hir_def::AdtId::EnumId(it)) => {
                     db.enum_data(it).variants.iter().for_each(|&(it, _)| {
-                        let def = it.into();
+                        let body = db.body(it.into());
-                        cb(def);
+                        cb(it.into());
-                        let body = db.body(def);
                         visit_body(db, &body, cb);
                     });
                 }
@@ -473,7 +483,7 @@ fn visit_module(
                         match item {
                             AssocItemId::FunctionId(it) => cb(it.into()),
                             AssocItemId::ConstId(it) => cb(it.into()),
-                            AssocItemId::TypeAliasId(_) => (),
+                            AssocItemId::TypeAliasId(it) => cb(it.into()),
                         }
                     }
                 }
@@ -483,7 +493,7 @@ fn visit_module(
         }
     }
 
-    fn visit_body(db: &TestDB, body: &Body, cb: &mut dyn FnMut(DefWithBodyId)) {
+    fn visit_body(db: &TestDB, body: &Body, cb: &mut dyn FnMut(ModuleDefId)) {
         for (_, def_map) in body.blocks(db) {
             for (mod_id, _) in def_map.modules() {
                 visit_module(db, &def_map, mod_id, cb);
@@ -553,7 +563,13 @@ fn salsa_bug() {
     let module = db.module_for_file(pos.file_id);
     let crate_def_map = module.def_map(&db);
     visit_module(&db, &crate_def_map, module.local_id, &mut |def| {
-        db.infer(def);
+        db.infer(match def {
+            ModuleDefId::FunctionId(it) => it.into(),
+            ModuleDefId::EnumVariantId(it) => it.into(),
+            ModuleDefId::ConstId(it) => it.into(),
+            ModuleDefId::StaticId(it) => it.into(),
+            _ => return,
+        });
     });
 
     let new_text = "
@@ -586,6 +602,12 @@ fn salsa_bug() {
     let module = db.module_for_file(pos.file_id);
     let crate_def_map = module.def_map(&db);
     visit_module(&db, &crate_def_map, module.local_id, &mut |def| {
-        db.infer(def);
+        db.infer(match def {
+            ModuleDefId::FunctionId(it) => it.into(),
+            ModuleDefId::EnumVariantId(it) => it.into(),
+            ModuleDefId::ConstId(it) => it.into(),
+            ModuleDefId::StaticId(it) => it.into(),
+            _ => return,
+        });
     });
 }

crates/hir-ty/src/tests/closure_captures.rs

@@ -24,6 +24,13 @@ fn check_closure_captures(ra_fixture: &str, expect: Expect) {
 
     let mut captures_info = Vec::new();
     for def in defs {
+        let def = match def {
+            hir_def::ModuleDefId::FunctionId(it) => it.into(),
+            hir_def::ModuleDefId::EnumVariantId(it) => it.into(),
+            hir_def::ModuleDefId::ConstId(it) => it.into(),
+            hir_def::ModuleDefId::StaticId(it) => it.into(),
+            _ => continue,
+        };
         let infer = db.infer(def);
         let db = &db;
         captures_info.extend(infer.closure_info.iter().flat_map(|(closure_id, (captures, _))| {

crates/hir-ty/src/tests/incremental.rs

@@ -1,4 +1,5 @@
 use base_db::SourceDatabaseFileInputExt as _;
+use hir_def::ModuleDefId;
 use test_fixture::WithFixture;
 
 use crate::{db::HirDatabase, test_db::TestDB};
@@ -19,7 +20,9 @@ fn foo() -> i32 {
             let module = db.module_for_file(pos.file_id.file_id());
             let crate_def_map = module.def_map(&db);
             visit_module(&db, &crate_def_map, module.local_id, &mut |def| {
-                db.infer(def);
+                if let ModuleDefId::FunctionId(it) = def {
+                    db.infer(it.into());
+                }
             });
         });
         assert!(format!("{events:?}").contains("infer"))
@@ -39,7 +42,9 @@ fn foo() -> i32 {
             let module = db.module_for_file(pos.file_id.file_id());
             let crate_def_map = module.def_map(&db);
             visit_module(&db, &crate_def_map, module.local_id, &mut |def| {
-                db.infer(def);
+                if let ModuleDefId::FunctionId(it) = def {
+                    db.infer(it.into());
+                }
             });
         });
         assert!(!format!("{events:?}").contains("infer"), "{events:#?}")
@@ -66,7 +71,9 @@ fn baz() -> i32 {
             let module = db.module_for_file(pos.file_id.file_id());
             let crate_def_map = module.def_map(&db);
             visit_module(&db, &crate_def_map, module.local_id, &mut |def| {
-                db.infer(def);
+                if let ModuleDefId::FunctionId(it) = def {
+                    db.infer(it.into());
+                }
             });
         });
         assert!(format!("{events:?}").contains("infer"))
@@ -91,7 +98,9 @@ fn baz() -> i32 {
             let module = db.module_for_file(pos.file_id.file_id());
             let crate_def_map = module.def_map(&db);
             visit_module(&db, &crate_def_map, module.local_id, &mut |def| {
-                db.infer(def);
+                if let ModuleDefId::FunctionId(it) = def {
+                    db.infer(it.into());
+                }
             });
         });
         assert!(format!("{events:?}").matches("infer").count() == 1, "{events:#?}")