//arrayTest.d
template I(T ...)
{
    alias I = T;
}

auto sumArrs(T0, T1)(T0[] a, T1[] b)
{
    a[] += b[]; //no ICE without this line
    return a;
}

pragma(msg, __traits(compiles, sumArrs(I!(string[], string).init)));



$dmd arrayTest.d
false
Statement::toCBuffer()

Internal error: s2ir.c 135



This is a very heavy reduced test-case from a much larger program. The original __traits(compiles, ...) was in a static if, not a pragma(msg, ...)