C# Compiler Warning 1685

Question

So, (seemingly) out of the blue, my project starts getting compiler warning 1685:

The predefined type \'System.Runtime.CompilerServices.ExtensionAtt

Answer 1

LINQBridge makes me immediately suspicious. The entire intent of this is to provide extension attribute/methods etc for 2.0 users. If you have 3.5 (System.Core.dll), don't use LINQBridge. If you do need LINQBridge in 3.5 for some obscure reason (and I can't think of one), then you might have to use an extern alias. But I really doubt you need it!