Change argument null exceptions to use ArgumentNullException.ThrowIfNull

[JamesNK]

ASP.NET Core checks and throws for null all over the place. e.g.

aspnetcore/src/HttpClientFactory/Polly/src/DependencyInjection/PollyHttpClientBuilderExtensions.cs

Lines 33 to 41 in a450cb6

	if (builder == null)
	{
	throw new ArgumentNullException(nameof(builder));
	}
	if (policy == null)
	{
	throw new ArgumentNullException(nameof(policy));
	}

ArgumentNullException.ThrowIfNull is used in modern code, but we should go through existing code to use ArgumentNullException.ThrowIfNull.

Pros: less code, small potential perf gains from inlining (exception moved into another method), consistency.

[JamesNK]

@stephentoub You're the author of many of the PRs in dotnet/runtime that switch code to use ArgumentNullException.ThrowIfNull. Is there a way to automate this, or did you update it manually?

[stephentoub]

When !! was a thing, there was an auto-fixer in VS that would use it. I employed that to roll out !! throughout dotnet/runtime. Then !! went away, and I primarily used regexes and other simple console-based tools to rewrite those !! into ThrowIfNull calls.

[JamesNK]

@stephentoub Do you know what happened to the fixer when !! was removed?

A fixer that converts from if (x == null) throw new ArgumentNullException(nameof(x)) to ArgumentNullException.ThrowIfNull seems like it would still be valuable.

[stephentoub]

A fixer that converts from if (x == null) throw new ArgumentNullException(nameof(x)) to ArgumentNullException.ThrowIfNull seems like it would still be valuable.

It would be. dotnet/runtime#68326 tracks it. @RikkiGibson wrote the initial analyzer/fixer and I believe was looking into revamping it for ThrowIfNull.

[JamesNK]

Ok!

FYI @rafikiassumani-msft @mkArtakMSFT @adityamandaleeka This has the area-runtime label, but changes apply in web frameworks and blazor areas as well.

Could delay doing anything here until an updated analyzer+fixer is ready and then change all null tests automatically.

[adityamandaleeka]

You mean I wrote a sweet regex for nothing? 😄

[adityamandaleeka]

src/Servers was done in #43502

[danmoseley]

We can use this analyzer dotnet/roslyn-analyzers#6293