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Looks like this is ready to review. I half expected worms to come out of this can but the CI looks reasonable.

Will this also affect the behaviour of cctors without beforefieldinit?

newFoo().X=1;// this should print "1" as the cctor of Foo is not beforefieldinitclassFoo{staticFoo(){}// opt-out beforefieldinitpublicstaticBarbar=new();publicintX;}classBar{publicBar(){Console.WriteLine(1);}}

I believe some applications rely on this behavior to do initialization.

The instance constructor is responsible for triggering the cctor in your example. The instance field access (on non-null this pointer) assumes that the cctor was triggered when the instance was created.