static using doesn't recognize method name, saying the name does not exist in the current context

Question

PLEASE NOTE: I am aware that a similar question has already been answered . It took me a while to find that question/answer because it assumes I recognized that it specifically involves extension methods, which I didn't at first. I was under the incorrect assumption that the static using feature could only be used with extension methods, so because of its perceived superfluity I didn't include that when searching.

The purpose of this post is to help people who don't recognize that.

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I have some code with the using static directive that introduced in C# 6:

using static MyNs.MyExtensionMethods;

I am trying to use an extension method defined in MyNs.MyExtensionMethods , and this works (as it always has):

foo.MyExtensionMethod();

But this does not:

MyExtensionMethod(foo);

I'm getting a compiler error "The name 'MyExtensionMethod' does not exist in the current context". What is going on?

Answer 1

As indicated by this answer , you cannot use the using static directive to allow unqualified access to extension methods , only to regular static methods (ie without the this keyword on the first argument). The reason is clearly stated in that answer, so I won't duplicate it here.