hir_ty: Expand macros at type position

3 files changed, 181 insertions, 2 deletions

diff --git a/crates/hir_ty/src/display.rs b/crates/hir_ty/src/display.rs
index e7c9dabc2..63bcb0640 100644
--- a/crates/hir_ty/src/display.rs
+++ b/crates/hir_ty/src/display.rs
@@ -997,7 +997,7 @@ impl HirDisplay for TypeRef {
                 write!(f, "dyn ")?;
                 f.write_joined(bounds, " + ")?;
             }
-            TypeRef::Error => write!(f, "{{error}}")?,
+            TypeRef::Error | TypeRef::Macro(_) => write!(f, "{{error}}")?,
         }
         Ok(())
     }
diff --git a/crates/hir_ty/src/lower.rs b/crates/hir_ty/src/lower.rs
index a035686bc..95ca5bdb0 100644
--- a/crates/hir_ty/src/lower.rs
+++ b/crates/hir_ty/src/lower.rs
@@ -15,7 +15,7 @@ use hir_def::{
     generics::{TypeParamProvenance, WherePredicate, WherePredicateTypeTarget},
     path::{GenericArg, Path, PathSegment, PathSegments},
     resolver::{HasResolver, Resolver, TypeNs},
-    type_ref::{TraitRef as HirTraitRef, TypeBound, TypeRef},
+    type_ref::{expand_type_ref, TraitRef as HirTraitRef, TypeBound, TypeRef},
     AdtId, AssocContainerId, AssocItemId, ConstId, ConstParamId, EnumId, EnumVariantId, FunctionId,
     GenericDefId, HasModule, ImplId, LocalFieldId, Lookup, StaticId, StructId, TraitId,
     TypeAliasId, TypeParamId, UnionId, VariantId,
@@ -287,6 +287,16 @@ impl<'a> TyLoweringContext<'a> {
                     }
                 }
             }
+            mt @ TypeRef::Macro(_) => {
+                if let Some(module_id) = self.resolver.module() {
+                    match expand_type_ref(self.db.upcast(), module_id, mt) {
+                        Some(type_ref) => self.lower_ty(type_ref.as_ref()),
+                        None => TyKind::Error.intern(&Interner),
+                    }
+                } else {
+                    TyKind::Error.intern(&Interner)
+                }
+            }
             TypeRef::Error => TyKind::Error.intern(&Interner),
         };
         (ty, res)
diff --git a/crates/hir_ty/src/tests/macros.rs b/crates/hir_ty/src/tests/macros.rs
index b8e373ed8..cbe05a5c1 100644
--- a/crates/hir_ty/src/tests/macros.rs
+++ b/crates/hir_ty/src/tests/macros.rs
@@ -1074,3 +1074,172 @@ fn macro_in_arm() {
         "#]],
     );
 }
+
+#[test]
+fn macro_in_type_alias_position() {
+    check_infer(
+        r#"
+        macro_rules! U32 {
+            () => { u32 };
+        }
+
+        trait Foo {
+            type Ty;
+        }
+
+        impl<T> Foo for T {
+            type Ty = U32!();
+        }
+
+        type TayTo = U32!();
+
+        fn testy() {
+            let a: <() as Foo>::Ty;
+            let b: TayTo;
+        }
+        "#,
+        expect![[r#"
+            147..196 '{     ...yTo; }': ()
+            157..158 'a': u32
+            185..186 'b': u32
+        "#]],
+    );
+}
+
+#[test]
+fn nested_macro_in_type_alias_position() {
+    check_infer(
+        r#"
+        macro_rules! U32Inner2 {
+            () => { u32 };
+        }
+
+        macro_rules! U32Inner1 {
+            () => { U32Inner2!() };
+        }
+
+        macro_rules! U32 {
+            () => { U32Inner1!() };
+        }
+
+        trait Foo {
+            type Ty;
+        }
+
+        impl<T> Foo for T {
+            type Ty = U32!();
+        }
+
+        type TayTo = U32!();
+
+        fn testy() {
+            let a: <() as Foo>::Ty;
+            let b: TayTo;
+        }
+        "#,
+        expect![[r#"
+            259..308 '{     ...yTo; }': ()
+            269..270 'a': u32
+            297..298 'b': u32
+        "#]],
+    );
+}
+
+#[test]
+fn macros_in_type_alias_position_generics() {
+    check_infer(
+        r#"
+        struct Foo<A, B>(A, B);
+
+        macro_rules! U32 {
+            () => { u32 };
+        }
+
+        macro_rules! Bar {
+            () => { Foo<U32!(), U32!()> };
+        }
+
+        trait Moo {
+            type Ty;
+        }
+
+        impl<T> Moo for T {
+            type Ty = Bar!();
+        }
+
+        type TayTo = Bar!();
+
+        fn main() {
+            let a: <() as Moo>::Ty;
+            let b: TayTo;
+        }
+        "#,
+        expect![[r#"
+            228..277 '{     ...yTo; }': ()
+            238..239 'a': Foo<u32, u32>
+            266..267 'b': Foo<u32, u32>
+        "#]],
+    );
+}
+
+#[test]
+fn macros_in_type_position() {
+    check_infer(
+        r#"
+        struct Foo<A, B>(A, B);
+
+        macro_rules! U32 {
+            () => { u32 };
+        }
+
+        macro_rules! Bar {
+            () => { Foo<U32!(), U32!()> };
+        }
+
+        fn main() {
+            let a: Bar!();
+        }
+        "#,
+        expect![[r#"
+            133..155 '{     ...!(); }': ()
+            143..144 'a': Foo<u32, u32>
+        "#]],
+    );
+}
+
+#[test]
+fn macros_in_type_generics() {
+    check_infer(
+        r#"
+        struct Foo<A, B>(A, B);
+
+        macro_rules! U32 {
+            () => { u32 };
+        }
+
+        macro_rules! Bar {
+            () => { Foo<U32!(), U32!()> };
+        }
+
+        trait Moo {
+            type Ty;
+        }
+
+        impl<T> Moo for T {
+            type Ty = Foo<Bar!(), Bar!()>;
+        }
+
+        type TayTo = Foo<Bar!(), U32!()>;
+
+        fn main() {
+            let a: <() as Moo>::Ty;
+            let b: TayTo;
+        }
+        "#,
+        expect![[r#"
+            254..303 '{     ...yTo; }': ()
+            264..265 'a': Foo<Foo<u32, u32>, Foo<u32, u32>>
+            292..293 'b': Foo<Foo<u32, u32>, u32>
+        "#]],
+    );
+}