You signed in with another tab or window. Reload to refresh your session.You signed out in another tab or window. Reload to refresh your session.You switched accounts on another tab or window. Reload to refresh your session.Dismiss alert
FS3261 : Nullness warning: The type 'IInterfaceFromExternalPackage' supports 'null' but a non-null type is expected.
Of course, there is no actual nullness issue here since I pass a non-null (singleton) instance of the type. However, I can find no way of silencing this warning apart from disabling it entirely for the file.
Choose one or more from the following categories of impact
Unexpected nullness warning (false positive in nullness checking, code uses --checknulls and langversion:preview).
Missing nullness warning in a case which can produce nulls (false negative, code uses --checknulls and langversion:preview).
Breaking change related to older null constructs in code not using the checknulls switch.
Breaking change related to generic code and explicit type constraints (null, not null).
Type inference issue (i.e. code worked without type annotations before, and applying the --checknulls enforces type annotations).
C#/F# interop issue related to nullness metadata.
Other (none of the categories above apply).
Operating System
Windows (Default)
What .NET runtime/SDK kind are you seeing the issue on
.NET SDK (.NET Core, .NET 5+)
.NET Runtime/SDK version
.NET SDK 9.0.100
Reproducible code snippet and actual behavior
No response
Possible workarounds
No response
The text was updated successfully, but these errors were encountered:
The interplay of [<AllowNullLiteral>] is not good here and the recommendation definitely is to migrate away from it towards nullable annotations.
However, I do understand the case of having a type defined elsewhere and not being able to change it.
If only the implementing type supports null but not the interface, you could do: let singleton:IInterfaceFromExternalPackage = ImplementorFromExternalPackage()
If the interface type itself supports null, the warning will still be raised for generic code with T:not null constraint.
For now, ignoring the warning will indeed remain the only option.
Issue description
Consider this code as a placeholder for a type defined in an external library:
Now consider the following:
This causes a compiler warning:
Of course, there is no actual nullness issue here since I pass a non-null (singleton) instance of the type. However, I can find no way of silencing this warning apart from disabling it entirely for the file.
Choose one or more from the following categories of impact
null
constructs in code not using the checknulls switch.null
,not null
).Operating System
Windows (Default)
What .NET runtime/SDK kind are you seeing the issue on
.NET SDK (.NET Core, .NET 5+)
.NET Runtime/SDK version
.NET SDK 9.0.100
Reproducible code snippet and actual behavior
No response
Possible workarounds
No response
The text was updated successfully, but these errors were encountered: