c: ClosureData, GoClosure

spec:

package c

func ClosureData[ClosureT any](closure ClosureT) Pointer
func GoClosure[ClosureT any](data Pointer) (closure ClosureT)

example:

// VisitChildren visits the children of a particular cursor, invoking the given
// visitor function for each child cursor. The traversal may be recursive,
// depending on the return value of the visitor function.
func VisitChildren(root Cursor, fn func(cur, parent Cursor) ChildVisitResult) uint {
	return uint(clang.VisitChildren(
		root, func(cur, parent Cursor, param clang.ClientData) ChildVisitResult {
			return c.GoClosure[func(cur, parent Cursor) ChildVisitResult](param)(cur, parent)
		}, c.ClosureData(fn)))
}

The issue specifies new ClosureData and GoClosure APIs in the c package, with a VisitChildren example showing the intended callback flow. Start by locating the c package and existing Pointer-related APIs; done means the two generic functions support the shown callback usage and the example can pass a Go closure through ClientData.