Swift: MAke TypeDecl.getFullName robust to when there's an ExtensionDecl extending more than one thing.

Author: geoffw0

swift/ql/lib/codeql/swift/elements/decl/TypeDecl.qll

@@ -109,13 +109,13 @@ class TypeDecl extends Generated::TypeDecl {
   cached
   string getFullName() {
     not this.getEnclosingDecl() instanceof TypeDecl and
-    not this.getEnclosingDecl() instanceof ExtensionDecl and
+    not count(this.getEnclosingDecl().(ExtensionDecl).getExtendedTypeDecl()) = 1 and
     result = this.getName()
     or
     result = this.getEnclosingDecl().(TypeDecl).getFullName() + "." + this.getName()
     or
     result =
-      this.getEnclosingDecl().(ExtensionDecl).getExtendedTypeDecl().getFullName() + "." +
-        this.getName()
+      unique(NominalTypeDecl td | td = this.getEnclosingDecl().(ExtensionDecl).getExtendedTypeDecl())
+            .getFullName() + "." + this.getName()
   }
 }