Conversion [-T, +U]
extends Object with Function1A class for implicit values that can serve as implicit conversions The implicit resolution algorithm will act as if there existed the additional implicit definition:
def $implicitConversion[T, U](x: T)(c: Conversion[T, U]): U = c(x)
However, the presence of this definition would slow down implicit search since
its outermost type matches any pair of types. Therefore, implicit search
contains a special case in Implicits#discardForView which emulates the
conversion in a more efficient way.
Note that this is a SAM class - function literals are automatically converted
to the Conversion values.
Also note that in bootstrapped dotty, Predef.<:< should inherit from
Conversion. This would cut the number of special cases in discardForView
from two to one.