Feature: Adhere to ContractVerification attribute

[Youssef1313]

I found ContractVerification attribute by chance 😄

The description says:

Instructs analysis tools to assume the correctness of an assembly, type, or member without performing static verification.

So I believe we should adhere to it, or at least, have an option to that.

This should be applied to most (all?) analyzers.

[Youssef1313]

This could even be a Roslyn feature, that is all analyzers (first-party and third-party) are configurable to whether to adhere to the attribute or not.

[Youssef1313]

Tagging @terrajobst @stephentoub since this is related to .NET API usage.

[stephentoub]

This attribute is specific to the System.Diagnostics.Contract system and rewriter. It is not related to Roslyn analyzers.

[Youssef1313]

@stephentoub Should Pure attribute be the same? It's currently checked by CA1806.

[stephentoub]

Personally, I don't think CA1806 should be paying attention to it.
dotnet/runtime#34098 (comment)
Or, rather, in and of itself, there's little technical harm in its doing so, except that it encourages further use of the attribute, which in my opinion is misguided.

[Youssef1313]

it encourages further use of the attribute, which in my opinion is misguided.

Yes, I'm one of those who wanted to add the attribute anywhere it could benefit from CA1806.

@mavasani Are you okay with dropping Pure from CA1806? (Probably only after a new runtime attribute is introduced because some customers may be relying on the existing attribute)

Tagging @sharwell @333fred as well (#1164 #1171)

@stephentoub I think it also makes sense for the API docs of Pure to be clear about the actual intent of the attribute

[mavasani]

We are not going to add support for ContractVerification.