Duplication on null conversion

[BillWagner]

We repeat ourselves, and classify an expression such as object o = null in two different ways:

10.2.7 Null literal conversions

An implicit conversion exists from the null literal to any reference type or nullable value type.

10.2.8 Implicit reference conversions includes:

• From the null literal (§6.4.5.7) to any reference-type.

We should classify it as one or the other.

[BillWagner]

/cc @jcouv

[Nigel-Ecma]

This is a leftover over from wiping the null type. Back in v1 §9.4.4.6 defined the null-literal to have the null type, and §13.1.4 (now §10.2.8) said “From the null type to any reference-type”. So no double naming.

I expect the term “null literal conversion” is too well used now to be dropped, and also that the conversion should be mentioned along with other implicit reference conversions.

We could alternatively view null literal conversions as a subset of implicit reference conversions. Maybe start §10.2.8:

The implicit reference conversions include the null literal conversion (§10.2.7) and the following:

or better wordsmithing.