Which among the following countries has accepted the policy of Dual Citizenship?

Dual citizenships has been in much of the debate over the years. Much of the developed countries such as US, UK, Australia, Switzerland have no restrictions on holding dual nationality, whereas countries such as Singapore, Austria, India, Saudi Arabia do not “recognize” or “restrict” dual citizenships, leading to automatic loss of citizenship upon acquiring other. Some countries such as Austria, Spain may still grant dual citizenships upon certain special conditions under exceptional cases like celebrities.