Please annotate SchemaRepository.TryLookupByType

[bkoelman]

I was reviewing some code and noticed a hidden bug: null could be returned, but there was no compiler warning. This is because TryLookupByType lacks the [NotNullWhen(true)] annotation, which is used, for example, in IPAddress.TryParse.

It would be helpful if SchemaRepository.TryLookupByType were annotated for nullability, similar to my workaround below:

#nullable enable
public static bool TryLookupByTypeSafe(this SchemaRepository schemaRepository,
    Type type, [NotNullWhen(true)] out OpenApiSchemaReference? referenceSchema)
{
    bool result = schemaRepository.TryLookupByType(type,
        out OpenApiSchemaReference? obliviousReferenceSchema);
    referenceSchema = result ? obliviousReferenceSchema : null;
    return result;
}
#nullable restore

And then the hidden bug becomes a compiler warning:

[aykutkaann]

Hi, I'd like to take this on. The fix looks straightforward — adding the [NotNullWhen(true)] annotation to the out parameter of TryLookupByType. I'll submit a PR shortly.

[aykutkaann]

It looks like this has already been addressed — TryLookupByType already has the [NotNullWhen(true)] annotation in the current codebase. This issue might be ready to close.

[bkoelman]

It was reopened because #nullable is still missing.