| > Did it drop the idea of assembly-wide opt-ins to stricter behaviour, meaning all NRTs can be reasoned about in the same way without considering a configuration flag somewhere like PHP? That does sound like an improvement. There's three levels of opt-in/out: * Source directives, for opting in/out a single scope (typically a whole file, but it can in be as small as a single method) * Project file directive via MSBuild property, for opting in/out a single project/assembly * The MSBuild property can be set in a Directory.build.props file, opting in/out all projects in a directory and its children In the long term, this property will likely be implicitly set to true for new projects (and perhaps all projects in the very long term), but for now everything is opt-in. Personally, I think that one of the biggest areas for tooling improvement is to better recognize when you're in a nullable-enabled context. It's pretty obvious when you look at source code, but when you've got a million LoC codebase and only a subset uses it, making developers aware of that is certainly a challenge. The other interesting thing to consider here is that even if the C# compiler freezes all future improvements to NRT analysis, there is a level of breaking changes that will occur over time as packages and frameworks adopt the feature and rev their versions. This transformation won't be without pain for existing codebases, and some may never adopt the feature (especially if they're the kind of codebase that doesn't really modernize). Interesting times ahead. |