如果将同一个文件包含到两个项目中而忽略CS0436“类型X与导入的类型X冲突”，会发生什么可怕的事情？

Question

I have a setup similar to this one - the same .cs file is included into more than one project (technically it resides in on project and a shortcut is added to the other so there's one copy of the file at all times) and then one of those projects is referenced from another one and I get type X conflicts with the imported type X warning. I know that I can fix this by crafting a class library referenced from both projects , but it's extra work that I'd rather avoid right now.

Is it safe to ignore the warning in this scenario? What bad things can happen?

Answer 1

The two types will not be interchangeable. You can have both declared separately, but they will be completely separate types. Type resolution can be really awkward - especially if an extern alias isn't possible. If they never leave the calling scope, that might be fine. However, in the general case it isn't a good idea and should be avoided. Type mismatch at runtime would be very likely, as could be type resolution failures at compile-time.

Another option in the future might be assembly neutral types ; this doesn't apply unless the compiler framework handles it - and it might be limited to the asp.net mvc stack for all I know, but in theory :

[AssemblyNeutral, AttributeUsage(AttributeTargets.Class
    | AttributeTargets.Interface | AttributeTargets.Struct,
    AllowMultiple = false, Inherited = false)]
internal sealed class AssemblyNeutralAttribute : Attribute { }

then whack [AssemblyNeutral] on your type.

Answer 2

Found this:

You have added a reference to the output of the project.

In other words, when trying to compile your project, AriaLibrary, to produce AriaLibrary.exe, the compiler imports the assembly AriaLibrary.exe. On disk, this file exists from a previous build.

As such, the compiler finds two of that class, one that it tries to compile now, and one from that previous build, and thus you get the warning.

Since there is no valid reason for having the output a project being imported as a reference to itself, you can safely remove that reference.

here: The type 'x' in 'x.cs' conflicts with the imported type 'x'

But in answer to your actual question, I'm (guessing) you could have issues from collisions/etc and form run time errors due to this?