2 files changed, 38 insertions, 1 deletions

diff --git a/crates/hir_ty/src/infer/pat.rs b/crates/hir_ty/src/infer/pat.rs
index dde38bc39..cde2ab82b 100644
--- a/crates/hir_ty/src/infer/pat.rs
+++ b/crates/hir_ty/src/infer/pat.rs
@@ -209,6 +209,18 @@ impl<'a> InferenceContext<'a> {
                 end_ty
             }
             Pat::Lit(expr) => self.infer_expr(*expr, &Expectation::has_type(expected.clone())),
+            Pat::Box { inner } => match self.resolve_boxed_box() {
+                Some(box_adt) => {
+                    let inner_expected = match expected.as_adt() {
+                        Some((adt, substs)) if adt == box_adt => substs.as_single(),
+                        _ => &Ty::Unknown,
+                    };
+
+                    let inner_ty = self.infer_pat(*inner, inner_expected, default_bm);
+                    Ty::apply_one(TypeCtor::Adt(box_adt), inner_ty)
+                }
+                None => Ty::Unknown,
+            },
             Pat::Missing => Ty::Unknown,
         };
         // use a new type variable if we got Ty::Unknown here
@@ -236,6 +248,6 @@ fn is_non_ref_pat(body: &hir_def::body::Body, pat: PatId) -> bool {
             Expr::Literal(Literal::String(..)) => false,
             _ => true,
         },
-        Pat::Wild | Pat::Bind { .. } | Pat::Ref { .. } | Pat::Missing => false,
+        Pat::Wild | Pat::Bind { .. } | Pat::Ref { .. } | Pat::Box { .. } | Pat::Missing => false,
     }
 }
diff --git a/crates/hir_ty/src/tests/patterns.rs b/crates/hir_ty/src/tests/patterns.rs
index aeb191c79..6a965ac4f 100644
--- a/crates/hir_ty/src/tests/patterns.rs
+++ b/crates/hir_ty/src/tests/patterns.rs
@@ -654,3 +654,28 @@ fn slice_tail_pattern() {
         "#]],
     );
 }
+
+#[test]
+fn box_pattern() {
+    check_infer(
+        r#"
+        #[lang = "owned_box"]
+        pub struct Box<T>(T);
+
+        fn foo(params: Box<i32>) {
+            match params {
+                box integer => {}
+            }
+        }
+        "#,
+        expect![[r#"
+            52..58 'params': Box<i32>
+            70..124 '{     ...   } }': ()
+            76..122 'match ...     }': ()
+            82..88 'params': Box<i32>
+            99..110 'box integer': Box<i32>
+            103..110 'integer': i32
+            114..116 '{}': ()
+        "#]],
+    );
+}