Error message change for type not found is not correct

[leppie]

using A = List<Bar>;

Reports in Roslyn:

Error CS0246: The type or namespace name 'List<Bar>' could not be found (are you missing a using directive or an assembly reference?)

In legacy compiler:

Error CS0246: The type or namespace name 'List' could not be found (are you missing a using directive or an assembly reference?)

To me, this is possibly confusing. In this case it is List<T> that could not be found. Not List<Bar>. And especially when going into some silly variations, eg List<"moo">.

I can understand it was a possible enhancement, but it would be better to say no generic type 'List' taking 1 argument.

Unfortunately, the Git history does not go back far enough to say why this change was done.

The point of interest is the whereText parameter in Binder.NotFound(...). See: https://github.com/dotnet/roslyn/blob/master/src%2FCompilers%2FCSharp%2FPortable%2FBinder%2FBinder_Symbols.cs#L1742

Related: #7387

[AdamMaras]

I agree, this is kind of strange. It may not be completely obvious to everybody that, in your example, it's List that can't be found, not Bar. Perhaps we can split the difference between the two?

The type or namespace name 'List' taking 1 generic argument could not be found (are you missing a using directive or an assembly reference?)

[YuvalItzchakov]

+1 for @AdamMaras suggestion. LGTM.

[leppie]

@AdamMaras The or namespace name bit should be dropped from the error message else it stays nonsensical :)

[leppie]

It might even be a good idea to try separate that error message completely to have a proper distinction between namespaces and types.