unified: Document bug for qualified type access

Author: asgerf

unified/ql/lib/codeql/unified/internal/mad/LegacyMaD.qll

@@ -156,6 +156,9 @@ private class Selector extends TSelector {
     // - The name "init" is too common to match on anyway. It is more precise to match on the type name in this case.
     //
     // So to wire up "init" calls correctly, we just use the type name as the method name.
+    //
+    // TODO: does not work for compound access like `String.Index(...)` where the type is `String.Index` but the
+    // call selector only uses `Index`.
     this = MkSelector(name, _, "init", argLabels, _)
   }
 

unified/ql/test/library-tests/mad/test.swift

@@ -56,3 +56,41 @@ func testProperties(
     configuration.tlsMaximumSupportedProtocolVersion = 0  // $ MISSING: isSink=tls-protocol-version
     configuration.tlsMinimumSupportedProtocolVersion = 0  // $ MISSING: isSink=tls-protocol-version
 }
+
+class Realm {
+    struct Configuration {}
+}
+
+func testQualifiedConstructors(
+    encodedOffset: Int,
+    encryptionKey: String,
+    fileURL: String,
+    seedFilePath: String
+) {
+    _ = String.Index(encodedOffset: encodedOffset)  // $ MISSING: isSink=string-length
+
+    _ = Realm.Configuration(
+        deleteRealmIfMigrationNeeded: false,
+        encryptionKey: encryptionKey,  // $ MISSING: isSink=encryption-key
+        fileURL: fileURL,  // $ MISSING: isSink=path-injection
+        inMemoryIdentifier: nil,
+        migrationBlock: nil,
+        objectTypes: nil,
+        readOnly: false,
+        schemaVersion: 0,
+        shouldCompactOnLaunch: nil,
+        syncConfiguration: nil)
+
+    _ = Realm.Configuration(
+        deleteRealmIfMigrationNeeded: false,
+        encryptionKey: encryptionKey,  // $ MISSING: isSink=encryption-key
+        fileURL: fileURL,  // $ MISSING: isSink=path-injection
+        inMemoryIdentifier: nil,
+        migrationBlock: nil,
+        objectTypes: nil,
+        readOnly: false,
+        schemaVersion: 0,
+        seedFilePath: seedFilePath,  // $ MISSING: isSink=path-injection
+        shouldCompactOnLaunch: nil,
+        syncConfiguration: nil)
+}