Use static foreach for correct scope inference

[dkorpel]

Part of #8113

Turns foreach over an AliasSeq into static foreach because of issue 21209 - scope attribute inference with does not work well with foreach. Without this, text and chain are not scope compatible.

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[thewilsonator]

can you add a test for this?

[dkorpel]

I added a test for text. I tried to add one for chain, but I was unable with the current compiler behavior. Because of issue 20150 (-dip1000 defeated by pure), I have to force chain to be impure somehow, which I can only do by using an impure copy constructor. But then scope inference fails even after this patch, and I don't know why.

// Test `scope` inference on `chain` parameters
version(unittest) private struct ImpureCopyCtor
{
    // not pure, for https://issues.dlang.org/show_bug.cgi?id=20150
    this(ref ImpureCopyCtor r) scope @nogc nothrow {}
    bool empty = true;
    void popFront() {}
    int* front;
}

@safe unittest
{
    auto chain1(ref ImpureCopyCtor r)
    {
        return chain(r, r);
    }
    scope ImpureCopyCtor r;
    chain1(r);
}

[thewilsonator]

CI seems stuck, can you please rebase or force push?

[RazvanN7]

The autotester seems to be stuck. Rebase this to restart it.

[thewilsonator]

Still stuck.