Comment out of line A will suppress the error in line B.
----
template ConstOf(T)
{
    alias const(T) ConstOf;
}
void main()
{
    shared(ConstOf!(int[])) x;  // line A

    struct S3 { int[10] a; }
    shared(S3) sh3;
    shared(int[]) sh3sub = sh3.a[];
    assert(pointsTo(sh3sub));   // line B
        // Error: cast(shared(const(int[])))sh3sub is not an lvalue
}
bool pointsTo(S)(ref const S source) @trusted pure nothrow
{
    return true;
}