My current bugbear: the C# 4.0 spec. Obviously, with a new toy like VS2010 the first thing you do is read all the documentation, yes? yes? anyone? Oh, just me then…
Now call me crazy, but I’m of the opinion that the spec is quite important in something like a programming language, yet at the moment the new shiny compiler is (by definition) not a compliant C# 4.0 compiler; it generates the wrong IL (according to the spec) for locks and field-like events.
I’m also still very unclear whether any other subtle changes have sneaked in (excluding the obvious changes for things like dynamic, variance, named arguments, optional parameters, etc).
I should stress: my aim here is in part to say “don’t bother re-reading the spec yet”, and in part to add one more grain of sand to the nagging I’ve been doing behind the scenes for ages on this topic. The right people already know about this – I just really want them to get it done and publish the darned spec! And ideally a change log, if they are feeling generous.
You know it is the right thing!