pass struct fields to chalk

Author: Austaras

crates/hir-ty/src/chalk_db.rs

@@ -768,8 +768,9 @@ pub(crate) fn adt_datum_query(
         phantom_data,
     };
 
-    // this slows down rust-analyzer by quite a bit unfortunately, so enabling this is currently not worth it
-    let _variant_id_to_fields = |id: VariantId| {
+    // this slows down rust-analyzer by quite a bit unfortunately
+    // but it's needed to trick chalk into impl Unsize
+    let variant_id_to_fields = |id: VariantId| {
         let variant_data = &id.variant_data(db.upcast());
         let fields = if variant_data.fields().is_empty() {
             vec![]
@@ -778,13 +779,13 @@ pub(crate) fn adt_datum_query(
             variant_data
                 .fields()
                 .iter()
+                .rev()
+                .take(1)
                 .map(|(idx, _)| field_types[idx].clone().substitute(Interner, &bound_vars_subst))
-                .filter(|it| !it.contains_unknown())
                 .collect()
         };
         rust_ir::AdtVariantDatum { fields }
     };
-    let variant_id_to_fields = |_: VariantId| rust_ir::AdtVariantDatum { fields: vec![] };
 
     let (kind, variants) = match adt_id {
         hir_def::AdtId::StructId(id) => {

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

@@ -536,17 +536,15 @@ fn test() {
 
 #[test]
 fn coerce_unsize_generic() {
-    check(
+    check_no_mismatches(
         r#"
 //- minicore: coerce_unsized
 struct Foo<T> { t: T };
 struct Bar<T>(Foo<T>);
 
 fn test() {
     let _: &Foo<[usize]> = &Foo { t: [1, 2, 3] };
-                         //^^^^^^^^^^^^^^^^^^^^^ expected &'? Foo<[usize]>, got &'? Foo<[i32; 3]>
     let _: &Bar<[usize]> = &Bar(Foo { t: [1, 2, 3] });
-                         //^^^^^^^^^^^^^^^^^^^^^^^^^^ expected &'? Bar<[usize]>, got &'? Bar<[i32; 3]>
 }
 "#,
     );
@@ -958,3 +956,24 @@ fn f() {
     "#,
     );
 }
+
+#[test]
+fn coerce_nested_unsized_struct() {
+    check_types(
+        r#"
+//- minicore: fn, coerce_unsized, dispatch_from_dyn, sized
+use core::marker::Unsize;
+
+struct Foo<T: ?Sized>(T);
+
+fn need(_: &Foo<dyn Fn(i32) -> i32>) {
+}
+
+fn test() {
+    let callback = |x| x;
+                  //^ i32
+    need(&Foo(callback));
+}
+"#,
+    )
+}

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

@@ -4694,21 +4694,21 @@ fn f<T: Send, U>() {
     Struct::<T>::IS_SEND;
   //^^^^^^^^^^^^^^^^^^^^Yes
     Struct::<U>::IS_SEND;
-  //^^^^^^^^^^^^^^^^^^^^Yes
+  //^^^^^^^^^^^^^^^^^^^^{unknown}
     Struct::<*const T>::IS_SEND;
-  //^^^^^^^^^^^^^^^^^^^^^^^^^^^Yes
+  //^^^^^^^^^^^^^^^^^^^^^^^^^^^{unknown}
     Enum::<T>::IS_SEND;
   //^^^^^^^^^^^^^^^^^^Yes
     Enum::<U>::IS_SEND;
-  //^^^^^^^^^^^^^^^^^^Yes
+  //^^^^^^^^^^^^^^^^^^{unknown}
     Enum::<*const T>::IS_SEND;
-  //^^^^^^^^^^^^^^^^^^^^^^^^^Yes
+  //^^^^^^^^^^^^^^^^^^^^^^^^^{unknown}
     Union::<T>::IS_SEND;
   //^^^^^^^^^^^^^^^^^^^Yes
     Union::<U>::IS_SEND;
-  //^^^^^^^^^^^^^^^^^^^Yes
+  //^^^^^^^^^^^^^^^^^^^{unknown}
     Union::<*const T>::IS_SEND;
-  //^^^^^^^^^^^^^^^^^^^^^^^^^^Yes
+  //^^^^^^^^^^^^^^^^^^^^^^^^^^{unknown}
     PhantomData::<T>::IS_SEND;
   //^^^^^^^^^^^^^^^^^^^^^^^^^Yes
     PhantomData::<U>::IS_SEND;