CODEWITHSUNDEEP
c#unity-game-enginewarningspragma
Bilal Akil
Bilal Akil

Reputation: 4755

Pragma to disable warning causing another warning (CS1692)

I've the following snippet of code in one of my C# classes:

    public override int GetHashCode()
    {
        // Thanks: https://stackoverflow.com/a/5910237

        if (set == null) return 0;

        int h = 0x14345843;

        foreach (T elem in set)
        {
            h = unchecked(h + set.Comparer.GetHashCode(elem));
        }

        return h;
    }

With this code, I'll receive a warning: "Non-readonly field referenced in 'GetHashCode()'".

As that is intended in this case, I added the following pragma to dismiss that warning: #pragma warning disable RECS0025.

However, after adding that pragma, I received a new warning only in the Unity Editor - not when building the code in Visual Studio:

warning CS1692: Invalid number

Double-clicking it would take me straight to that #pragma warning disable RECS0025 line.

What am I doing wrong here? The goal is to suppress the RECS0025 warning, of course without causing another warning.

Extra: I tried disabling the CS1692 warning around the RECS0025 pragmas, but that didn't work either; the CS1692 error continued occurring.

Extra extra: I've some code elsewhere as follows:

#pragma warning disable RECS0108
    static SharedPool<Tuple<HierarchyMember, string>, ReactiveProperty<T>> _sharedPool;
#pragma warning restore RECS0108

This does not cause the CS1692 error to occur. That is, if I remove the #pragma warning disable RECS0025 from around the GetHashCode function, but leave the above RECS0108 pragma in, there will be no CS1692 warning.

Not sure how this adds up with the two provided answers.

Upvotes: 3

Views: 2604

Answers (2)

Zer0
Zer0

Reputation: 7354

That's due to the non-numeric prefix. I'm guessing Unity is using an old compiler or not the most recent spec of C#? I'm not familiar with the Unity compiler at all, but this should fix it.

Be aware this disables all warnings, so I'd limit it in scope as much as possible.

public override int GetHashCode()
{
    // Thanks: https://stackoverflow.com/a/5910237
#pragma warning disable
    if (set == null) return 0;

    int h = 0x14345843;

    foreach (T elem in set)
    {
        h = unchecked(h + set.Comparer.GetHashCode(elem));
    }

    return h;
#pragma warning restore
}

Upvotes: 3

Marc Gravell
Marc Gravell

Reputation: 1062502

Before C# 6, you aren't allowed to use prefixes on pragma instructions - everything is assumed to be intended for the C# compiler.

So to take your C# example:

#pragma warning CS1692

and

#pragma warning 1692

are equivalent, but the first one is not valid until C# 6. Unfortunately, Unity uses an older compiler. There is no way of specifying RECS0025 in source code without that. Options:

  • fix the error - presumably by calculating the hashcode at construction and asserting that the set contents cannot ever change (it should be a read-only set anyway to be used in this way)
  • ignore the error visually
  • find another way to suppress that warning
  • disable the tool that is raising the warning

I'd go with the first one.

Upvotes: 3

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