struct S
{
    int bug()
    {
        bool b;

        void toggle()
        {
            if (b)
                b = false;
        }

        void trigger()
        {
            toggle();
        }

        trigger();
        return 0;
    }
}

enum interpret = S().bug();

----

When compiling with -inline this gives the following error.
bug.d(9): Error: integral constant must be scalar type, not void.

This happens because the IfStatement gets rewritten to an
AndAndExp during inlining. The AndAndExp is given the type void
which seems reasonable as it is a statement.
Later during interpretation the condition evaluates to true and
an IntegerExp with AndAndExp's type (void) is created, which causes the error.

I can't think of any && expression that doesn't have a bool result,
so using bool for the Integer could be a fix.

One thing that seems a little strange is that it is
the interpretation that actually triggers inlining (through calling semantic3 on the nested function). This inverts the usual order and could possibly
expose more bugs.