Why did the BeforeFieldInit behavior change in .NET 4?

Question

In C# 4, the behavior of types without the beforefieldinit flag was changed, so now a type initializer can call before first use of any static field of the class.

My questions are why has the C#/.NET team changed that behavior? What is the main reason? Can you show any practical example where this change makes any sense?

Answer 1

The behaviour has always been within the bounds of what's documented - it's just that it changed from being eager to lazy in .NET 4.

I suspect the JIT team managed to find a way to make it lazy without a performance penalty... or possibly it helps performance somewhere else. This is likely to only be one such change in behaviour within the .NET 4 CLR vs the .NET 2 CLR... it happens that I noticed it, but I doubt that many other people did. I think it's entirely reasonable for the JIT team to adjust things as they see fit, within the documented guarantees.

Ultimately, if this makes your code fail, you've got a bug already.