We once again saw a few reports of folks running into the CS1668 warning every time they used the C# compiler when we released Beta 2. For those who use the /warnaserror+ compiler option, it blocks compilation as it gets promoted to an error.

To some users, this diagnostic comes as a surprise. We added it very early in the Whidbey (C# 2.0/VS 8.0) product cycle to help those who made a simple typo when modifying their LIB environment variable (or when using the /lib compiler option) but it's still a new thing to deal with for those trying out Whidbey for the first time. Tons of custo