Comment 0 for bug 396095

Here is a little program that makes the compiler crash with an internal error. It involves assigning to the time derivative of a user defined class. The error happens in the code generator.

I can't spontaneously understand the error to fix it, so I file a bug.

This is the program that crashes the compiler. When the alternative, commented out, code is used, the program compiles.
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class Vec2:
    data x: Float role_unknown
    data y: Float role_unknown

    func __assign__(this, other):
        x = other.x
        y = other.y

    func __diff__(this):
        data res: Vec2
        replace_attr(res.x, $x)
        replace_attr(res.y, $y)
        return res

data vg: Vec2
vg.x = 0
vg.y = -9.81

class Throw:
    data v: Vec2

    func dynamic(this):
        #$v.x = 0 #This code
        #$v.y = -9.81 #works
        $v = vg #This code crashes the compiler

compile Throw
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