Don't specialize function templates

Reason

You can't partially specialize a function template per language rules. You can fully specialize a function template but you almost certainly want to overload instead -- because function template specializations don't participate in overloading, they don't act as you probably wanted. Rarely, you should actually specialize by delegating to a class template that you can specialize properly.

Example

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Exceptions: If you do have a valid reason to specialize a function template, just write a single function template that delegates to a class template, then specialize the class template (including the ability to write partial specializations).

Enforcement

• Flag all specializations of a function template. Overload instead.