The correct answer is "none."
Smoking, parking, and evacuation routes have nothing to do with the Second Amendment and so would not be impacted by that provision of the U.S. Constitution.
As for the designation of schools as "gun-free zones," a law like that would be constitutional if adopted by a state or local government.
If adopted by Congress as a federal law, it runs into a constitutional problem that is also distinct from the Second Amendment: the Interstate Commerce Clause. In a case called United States v. Lopez, the U.S. Supreme Court decided in 1995 that the federal Gun-Free Zones Act of 1990 was beyond Congress' authority to enact under the Interstate Commerce Clause. The Court did not decide whether the law would conflict with the Second Amendment.
In 1997 Congress approved, and President William J. Clinton signed, a bill that amended the Gun-Free Zones Act to make clear that it applies only to firearms that have "moved in or otherwise affect[] interstate commerce." Several federal appeals courts have upheld the amended version of the federal Gun-Free Zones Act as consistent with the Interstate Commerce Clause.
The reach of the Second Amendment appears to be quite limited. In a 2008 decision in District of Columbia v. Heller, the Supreme Court ruled that it a District of Columbia ordinance that forbade a homeowner from possessing a handgun in the home violated the Second Amendment. Justice Antonin Scalia wrote for the majority that
Like most rights, the Second Amendment right is not unlimited. It is not a right to keep and carry any weapon whatsoever in any manner whatsoever and for whatever purpose: For example, concealed weapons prohibitions have been upheld under the Amendment or state analogues. The Court's opinion should not be taken to cast doubt on longstanding prohibitions on the possession of firearms by felons and the mentally ill, or laws forbidding the carrying of firearms in sensitive places such as schools and government buildings, or laws imposing conditions and qualifications on the commercial sale of arms.
(Emphasis added).
In 2010, the Supreme Court ruled in McDonald v. City of Chicago that the Second Amendment applies to state and local ordinances, regulations, and statutes as well as to the federal government.
Some federal appeals courts have held that the Second Amendment gives an individual the right to carry a personal firearm for self-defense while in public. However, there is a split of authority on that question.
No court has held that the Gun-Free Zones Act of 1990 violates the Second Amendment. Nor has any court held that local or state laws that restrict or forbid possession of firearms in schools violate the Second Amendment. Only Hawaii, New Hampshire, and Wyoming do not generally prohibit people from bringing guns onto the property of K–12 schools.
