Dispose cache only once

[mrinaldi]

This PR is an attempt to fix #240.

[smoothdeveloper]

Bump, can we get this merged and released in a new beta?

[dsevastianov]

I'm still unable to reproduce it, can you please provide step by step instructions with relevant code, minimal test would be ideal.

[smoothdeveloper]

Can we get a beta released with this merged in? this is really making the library unusable and has been open for quite a while.

Seeing how the cache is used, I doubt a test can be added without refactoring internal class, we can create a separate ticket about testing usage of the cache.

[dsevastianov]

I went through steps in VS ticket and still couldn't reproduce it. Are you guys absolutely sure you don't have something like F# power tools installed as well?

That notwithstanding, I'm not sure I like what proposed change is achieving. First of all, disposeCache function needs to be renamed as it doesn't actually dispose cache anymore. Second, I think it should be clearing cache rather then disposing it as it makes SingleRootTypeProvider unstable, which apparently results in the issue you are experiencing. I guess if 'Invalidate' replaces types in cache it will work close to what is expected, but explicitly clearing it would address all kinds of dirty state stuck after invalidation. Does it make sense?

[smoothdeveloper]

Good call @dsevastianov, I'll try without VFPT, and I'll also try to confirm the bug doesn't happen with this merged in and report back.

I agree the fix might not be ideal, but if it does remove the issue, it will definitely be an improvement to the end-user.

[smoothdeveloper]

@dsevastianov the issue also happens with VFPT uninstalled. I'm going to try a fix following your instructions (clearing cache instead of disposing).