Allow later var variable type detection

[wanton7]

Later type detection for variable defined with var should be allowed. Following should work

var value;
lock (_obj)
{
   value = GetValue();
}

and

var value = null;
if (condition)
{
  value = GetValue();
}

[HaloFour]

I think it would make the code a lot less readable to have to scan through the code to find an eventual initialization to determine the type of the variable.

Given that value is mutable when would you suggest the compiler determine the type given multiple assignments? What about if there are assignments in different branches of different types? For example, what if GetValue() returns int in your second case?

[wanton7]

@HaloFour for second case compiler error if GetValue returns int or something that isn't nullable.

For multiple assingments it would work like ? : does now. Meaning types would have to be compatible.

Visual Studio already shows var variables type if put mouse pointer top of it. So no need to scan through code.

[DavidArno]

You first example would be addressed with lock and using expressions:

var value = lock(_obj) GetValue();

Your second example is already handled with a ternary expression:

var value = condition ? GetValue() : null;

[jcouv]

Relates to #520 (allow var x; with inference from later usage)