Test:
---
module main;

import core.checkedint;
import std.stdio;

// This yields "internal compiler error: in expand_intrinsic_arith", etc.
auto test(ref bool overflow) {
    return adds(1, 1, overflow);
}

void main(string[] args)
{
    bool overflow = false;
    writeln(test(overflow));
    writeln(overflow);
    stdin.readln();
}
---

Causes:
---
main.d: In function ‘test’:
main.d:8:5: internal compiler error: in expand_intrinsic_arith, at
d/d-codegen.cc:2422
     return adds(1, 1, overflow);
     ^