ABI for static arrays

[Andrej Mitrovic]

This compiles:

void foo(int* ptr) { }
void main()
{
    int[2] arr;
    test(arr);
}

What was the use-case for making static arrays implicitly convert to a
pointer to the first element? Was this done to ease C compatibility?

It seems like it could cause trouble since static arrays lay on the
stack. A somewhat elaborate example:

import std.stdio;

void foo(int* ptr)
{
    static int* val;
    if (!val) val = ptr;
    writeln(*val);
}

void test()
{
    int[2] x = 1;
    foo(x);
}

void main()
{
    test();
    foo(null);
}

Writes:

$ 1
$ 1245036

It even works with @safe, and one of the safe rules are: "No casting
from any non-pointer type to a pointer type.". Maybe that only applies
to the function body, but I think it should probably apply to the
arguments as well.

Anyway I don't see why we need it, we can easily use arr.ptr to pass
the pointer to the first element. Unless there are good benefits, I'd
ask if any code in the wild would break if it were changed? I've
certainly never seen it used.