Add manual implementation of the Hashable protocol

Sources/Identity/Identity.swift

@@ -77,10 +77,18 @@ extension Identifier: CustomStringConvertible {
     }
 }
 
+// MARK: - Hashable support
+
+extension Identifier: Hashable where Value.RawIdentifier: Hashable {
+    public func hash(into hasher: inout Hasher) {
+        hasher.combine(ObjectIdentifier(Value.self))
+        hasher.combine(rawValue)
+    }
+}
+
 // MARK: - Compiler-generated protocol support
 
 extension Identifier: Equatable where Value.RawIdentifier: Equatable {}
-extension Identifier: Hashable where Value.RawIdentifier: Hashable {}
 
 // MARK: - Codable support
 

Tests/IdentityTests/IdentityTests.swift

@@ -76,6 +76,21 @@ final class IdentityTests: XCTestCase {
         XCTAssertEqual(intID.description, "7")
     }
 
+    func testIdentifierHashValue() {
+        struct FirstModel: Identifiable {
+            let id: ID
+        }
+
+        struct SecondModel: Identifiable {
+            let id: ID
+        }
+
+        let first = FirstModel(id: "0")
+        let second = SecondModel(id: "0")
+
+        XCTAssertNotEqual(first.id.hashValue, second.id.hashValue)
+    }
+
     func testAllTestsRunOnLinux() {
         verifyAllTestsRunOnLinux()
     }
@@ -88,6 +103,7 @@ extension IdentityTests: LinuxTestable {
         ("testCodableIdentifier", testCodableIdentifier),
         ("testIdentifierEncodedAsSingleValue", testIdentifierEncodedAsSingleValue),
         ("testExpressingIdentifierUsingStringInterpolation", testExpressingIdentifierUsingStringInterpolation),
-        ("testIdentifierDescription", testIdentifierDescription)
+        ("testIdentifierDescription", testIdentifierDescription),
+        ("testIdentifierHashValue", testIdentifierHashValue),
     ]
 }