How to deal with "object is not null here" warning in Visual Studio 2022 and .NET Core?-CodePudding

I am developing a .NET Core 6 application.

In one part of the code I have this:

catch (Exception ex)
{
    _logger.LogError(ex.GetMessage());
    string error = "Por favor, contáctese con soporte técnico.";
    if (ex.InnerException != null)
        error = string.Concat("\n\n", ex.InnerException.Message);
    return Json($"ERROR: Existió un error al iniciar sesión. {error}");
}

when I pass the mouse over ex in ex.GetMessage(), this warning appears:

that means "ex is not NULL here". What is that? How can I deal with this?

CodePudding user response：

CA2254 indicates that log messages shouldn't vary per call, but that parameters should.

So instead of logging ex.Message, you log something like:

_logger.LogError("Something went wrong while fooing the bar: {message}", ex.Message);

But actually don't, because you don't just want to log the exception message, but the whole thing, depending on your logging configuration; let the logging framework handle exception logging.

So:

_logger.LogError("Something went wrong while fooing the bar", ex);

CodePudding user response：

This is Rosyln's Flowstate or NullableFlowState. The message is purely informative (it just somewhat looks like an error/warning because of the CA2254 message as well - if it weren't for that, ex probably wouldn't even have those dots under it).

When the nullable feature is enabled, the compiler will track the flow state of expressions throughout a method, regardless of what the variable was declared as.

You can read some more information about this here.

I think the actual source for this can be found here.