Composed target-typed inference for switch expression and deconstruction

[huoyaoyuan]

Currently, this code compiles:

MemberInfo info = null;
Action<object> getValue = null;

getValue = info switch
{
    PropertyInfo pi => () => pi.GetValue(d),
    FieldInfo fi => () => fi.GetValue(d)
};

This code also compiles:

PropertyInfo pi = null;
(type, getValue) = (pi.PropertyType, () => pi.GetValue(d));

However, when combing switch expression and tuple together, this code cannot compile:

MemberInfo info = null;
Action<object> getValue = null;
Type type = null;

(type, getValue) = info switch
{
    PropertyInfo pi => (pi.PropertyType, () => pi.GetValue(d)),
    FieldInfo fi => (fi.FieldType, () => fi.GetValue(d))
};

The compiler cannot infer type of lambda.
I'm not sure whether this belongs to target-typed expressions or common types. Maybe related to #2823.

[alrz]

This is a part of #1394. Per #1394 (comment) it includes switch expressions as well.

[gafter]

/cc @jcouv