项目的目标 .NET 框架取决于 Visual Studio 版本？

Question

I have a funny situation where the C# project targets version of .NET framework depending on Visual Studio version rather than depending on selected .NET target version in Application tab of project's properties.
I had VS2013 premium, update 4, installed and the given project targets .NET 3.5.
Afterwards I've installed VS2015 Enterprise edition and opened solution with the given project with VS2015. Resharper suggested use of nameof() operator (which is .NET 6.0 feature) and this compiled, but when I open given solution in VS2013 it doesn't compile anymore.

Here's the screenshot of Application tab for the given project:

Here's the code snippet from the project when I open it in VS2015:
Which compiles successfully.

And here's the code snippet from the project when I open it in VS20103:

Which doesn't compile.

Any clues about this?

UPDATE:
To rephrase my question. Why does the given project (that targets .NET 3.5) compile at all in VS2015 even though I've used .NET 6.0 feature (nameof() operator)?

Answer 1

This is normal behaviour. If you try to compile something .NET 4.0 specific in VS 2005, you will get the same result. Using a certain VS version you can only develop using up to a certain .NET version.

If I remember correctly:

VS 2005 - .NET 2.0
VS 2008 - .NET 3.5
VS 2010 - .NET 4.0
VS 2013 - .NET 4.5

Update: The .NET version is indeed not relevant in this case, as the nameof operator is a feature of the Roslyn compiler. Nothing more, nothing less. The VS 2013 definitely uses a different one (at least a compiler which does not cover up with C# 6), therefore it does not compile.