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.NET 4.6 Optimizer Bug Causes Methods To Get Wrong Parameters
tobiasly writes: A serious bug in the just-released .NET 4.6 runtime causes the JIT compiler to generate incorrectly-optimized code which results in methods getting called with different parameters than what were passed in. Nick Craver of Stack Exchange has an excellent write-up of the technical details and temporary workarounds; Microsoft has acknowledged the problem and submitted an as-yet unreleased patch.
This problem is compounded by Microsoft's policy of replacing the existing .NET runtime, as opposed to the side-by-side runtimes which were possible until .NET 2.0. This means that even if your project targets .NET 4.5, it will get the 4.6 runtime if it was installed on that machine. Since it's not possible to install the just-released Visual Studio 2015 without .NET 4.6, this means developers must make the difficult choice between using the latest tools or risking crippling bugs such as this one.
This problem is compounded by Microsoft's policy of replacing the existing .NET runtime, as opposed to the side-by-side runtimes which were possible until .NET 2.0. This means that even if your project targets .NET 4.5, it will get the 4.6 runtime if it was installed on that machine. Since it's not possible to install the just-released Visual Studio 2015 without .NET 4.6, this means developers must make the difficult choice between using the latest tools or risking crippling bugs such as this one.
Since it's not possible to install the just-released Visual Studio 2015 without .NET 4.6, this means developers must make the difficult choice between using the latest tools or risking crippling bugs such as this one.
If you're a dev, you shouldn't be chasing versions. Find a stable version, stick with it through your project. SE already has enough of that "stuff changing out from under me" feel without adding to the issue.
You don't need to stick to it forever, just long enough for it to become stable and reasonably well accepted. You don't need to be the early adopter in the middle of active development. When you've got some breathing room (your stuff is relatively stable) and aren't going to waste a weeks worth of your team's money, then you can think about moving to newer versions of tools, libraries, etc..