C#•4y ago

Is there any reason why comparing struct types with null does not result in compile error?

When comparing struct types with null, it is always false. So, why doesn't the compiler throw compilation error?
When and where do we want to compare struct types with null?! never because it is a logical bug

Thinker•12/5/22, 8:35 PM

Because afaik

==

==

is by default comparing an object to an object, so it boxes the struct and then compares it to

null

null

Thinker•12/5/22, 8:35 PM

And yes you're right, for a struct will never return true.

GladiatorOP•12/5/22, 8:36 PM

Thanks

GladiatorOP•12/5/22, 8:37 PM

my wrong
It says

GladiatorOP•12/5/22, 8:37 PM

So, it is compile time error

mtreit•12/5/22, 8:37 PM

Turn on warning level 6 and it should flag it.

GladiatorOP•12/5/22, 8:38 PM

==

==

has been overloaded, it says it returns false always. OK, prefect

mtreit•12/5/22, 8:38 PM

I'm fixing like a zillion places in my codebase where we compare DateTime to null right as we speak, because we increased the warning level and now that's being flagged all over the place.

GladiatorOP•12/5/22, 8:39 PM

Because my class Node was class

GladiatorOP•12/5/22, 8:39 PM

but now it is struct, I should check null conditions in all places

and replace it

Original message was deleted

mtreit•12/5/22, 8:40 PM

What do you mean?

GladiatorOP•12/5/22, 8:40 PM

Also, I do not know about warning flags. My env is Unity + Rider

mtreit•12/5/22, 8:40 PM

I don't know what you mean by latest.

mtreit•12/5/22, 8:41 PM

AnalysisLevel is something different

mtreit•12/5/22, 8:41 PM

I'm talking about this:
<WarningLevel>6</WarningLevel>

mtreit•12/5/22, 8:43 PM

Good question.

mtreit•12/5/22, 8:43 PM

I don't know.

mtreit•12/5/22, 8:46 PM

I only actually found out about level 6 because our official build system somehow enabled that recently and it started flagging a bunch of issues that did not reproduce when building locally. So I cranked up the warning level to 6 for local builds and now I've been spending hours fixing flagged issues.

mtreit•12/5/22, 8:48 PM

If you want the maximum possible analysis level, set it to "preview"

mtreit•12/5/22, 8:49 PM

I'm not sure what "latest" includes.

Original message was deleted

333fred•12/5/22, 11:20 PM

This is the documentation page, yes

333fred•12/5/22, 11:20 PM

So, why doesn't the compiler throw compilation error?

This is what we called a load-bearing bug

333fred•12/5/22, 11:20 PM

The native compiler didn't error for this code. When we created roslyn, we tried to fix it

333fred•12/5/22, 11:20 PM

Then we found we couldn't compile VS or Office

333fred•12/5/22, 11:21 PM

It, and the other warning wave warnings on that page, are the native compiler bugs that are so pervasive we had to make an entire new feature to fix them