Visual studio 2010 compilation issue - visual-studio-2010

Question

I have a project in Visual Studio 2010 with target to framework 3.5 with some code like this:
public class Test {
private object _field;
private Action defaultAction = null;
public Test(Action a)
{
defaultAction = a;
}
public Test()
: this(() => { _field = new object(); })
{
}
}
When I compile the project from the VS reports a compile error at line 11.
When I compile the project from the command line with "C:\Windows\Microsoft.NET\Framework\v3.5\msbuild.exe Test.sln" compiles successfully.
In fact this code compiles in VS2008 but in VS2010 with target to framework 3.5, doesn't.
Any idea about what is happend?
Update
To fix the code in V2010 I changed as follows (this is equivalent to origian code):
public class Test {
private object _field;
private Action defaultAction = null;
public Test(Action a)
{
defaultAction = a;
}
public Test()
{
defaultAction = () => {_field = new object();}
}
}
But what worries me is that Visual Studio is compiling my code with framework 4.0 and this may cause other errors when deploying my application in the customer's environment (framework 3.5).

Answer 1

I don't have access to VS2008 or .NET 3.5 at the moment so I can't investigate why it's compiling for you. There might be an explanation linked from What's New in the .NET Framework 4
What I can offer however is a fix to get it compiling in VS2010. By declaring _field as static, an instance of it will be available in the constructor of the Test class.
Replace the second line of your posted code with this and the code should compile:
private static object _field;