Add a test to see if tuple struct gets combined

tests/source/pattern.rs

@@ -48,3 +48,18 @@ fn issue_1874() {
 y
     }
 }
+
+fn combine_patterns() {
+    let x = match y {
+        Some(
+            Some(
+                Foo {
+                    z: Bar(..),
+                    a: Bar(..),
+                    b: Bar(..),
+                },
+            ),
+        ) => z,
+        _ => return,
+    };
+}

tests/target/pattern.rs

@@ -63,3 +63,14 @@ fn issue_1874() {
         y
     }
 }
+
+fn combine_patterns() {
+    let x = match y {
+        Some(Some(Foo {
+            z: Bar(..),
+            a: Bar(..),
+            b: Bar(..),
+        })) => z,
+        _ => return,
+    };
+}