16.4.10 Highlight differences with static constructors?

[jskeet]

Static constructors for structs follow most of the same rules as for classes.

That makes one wonder what rules it doesn't follow. I think we should elaborate.

Additionally:

• It would be good to reference 15.12 at the end of the above sentence
• This subsection isn't referenced from 16.4.1, unlike almost all other subsections.

[Nigel-Ecma]

Agreed in principle. Someone should determine in what way the differ, if they do, and wordsmith a suitable §16.4.10; and add it to the list in §16.4.1 - I expect the latter is just an oversight; and make this a Proposal.

[jonpryor]

The entirety of §16.4.10 is weird. It begins:

Static constructors for structs follow most of the same rules as for classes.

Should this not provide a link to §15.12?

Ignoring that, the section then proceeds:

The execution of a static constructor for a struct type is triggered by the first of the following events to occur within an application domain:

• An explicitly declared constructor of the struct type is called.

This sounds like it's providing an exhaustive list, but it's at minimum missing use of a static member; cribbing from §15.12:

• Any of the static members of the class type are referenced.

I also don't understand why this bullet point was removed:

An instance member of the struct is referenced.

The static constructor appears to be executed before an instance member is referenced, at least in this example:

using System;
struct Point {
    static Point ()
    {
        Console.WriteLine ("# Point..cctor");
    }

    int x;
    public int X {
        get {return x;}
        set {x = value;}
    }
    public Point(int x, int y) {
        this.x = x;
    }
}

class App {
    public static void Main ()
    {
        Console.WriteLine ("Start.");
        var p = new Point ();
        Console.WriteLine ("p.X={0}", p.X);
        Console.WriteLine ("Done.");
    }
}

Program output with mono 4.3.2:

Start.
# Point..cctor
p.X=0
Done.

Removing the access to p.X also removes the execution of the static constructor.

[jskeet]

All comments prior to this one were before we removed section 7. I've updated the title only.

[Nigel-Ecma]

Clause numbers in all comments above updated, it was getting confusing!

[Nigel-Ecma]

What the semantics are here needs to be resolved, it shouldn't be punted again. I have a vague recollection that this was a discussion area for the CLI and it's semantics may have changed as a result – which I expect impacts the C# compilers, and in turn this Standard... Labelling appropriately

[jskeet]

Related: #125