Struct's default constructor does not get called implicitly

[TriEdgeAIDeprecated]

C# Code:

Vector3 vector;
vector.x = m00 * v.x + m10 * v.y + m20 * v.z + m30;

Generated JavaScript code:

var vector;
vector.x = this.m00 * v.x + this.m10 * v.y + this.m20 * v.z + this.m30;

Which results in an error, when running it. Instead it should be like so:

var vector = new $Vector3();
vector.x = this.m00 * v.x + this.m10 * v.y + this.m20 * v.z + this.m30;

[erik-kallen]

When I try to compile a minimal sample using VS2012 I get a compilation error. Which setup are you using? If you're not using Visual Studio it's mono's responsibility to report this error, and perhaps it does not support that.

[TriEdgeAIDeprecated]

I am using Visual Studio 2015 Preview. Try this code:

using System;
using System.Runtime.CompilerServices;

namespace Test
{
    [Mutable]
    struct Vector3
    {
        public float x;
        public float y;
    }

    class Program
    {
        static Vector3 GetIt()
        {
            Vector3 vector;
            vector.x = 5.0f;
            vector.y = 10.0f;
            return vector;
        }

        static void Main()
        {
            Vector3 vector = GetIt();
            Console.WriteLine(vector.x + ", " + vector.y);
        }
    }
}

As long as you initialize all fields of the returned struct within every possible code path in the function, it is OK not to explicitly call the constructor.

[erik-kallen]

Ah, thank you!

[TriEdgeAIDeprecated]

Another case:

Vector3[] arr = new Vector3[5];
arr[0].x = 0.0f; // error, arr[0] is undefined and has no member 'x', but that isn't how it should be

[erik-kallen]

@TriEdgeAI That case is going to be very hard (impossible?) to fix. At least I have no idea of how to do it.

[TriEdgeAIDeprecated]

I am not aware how the compiler works internally, but can't you generate an additional for-loop which initializes all elements to default(T), whenever new T[] is performed, such that T is value type?