Re: lily: fix some type conversion warnings (issue 557190043 by address@hidden)

[hanwenn]

There are two problems that are tangentially related, and I think the
discussion comes from us wanting to solve different problems. 

My problem is that it is very distracting to change the C++ code base if
there are compiler warnings about existing code. So, I want a code base
that compiles with zero warnings as a starting point.

There is a different problem, which that there are some dubious casts in
our source code. I think that you, ie. Dan and David, want to address
that problem.

Here is a proposal that can make both of us happy:

1) fix all warning provisorially, by adding the casts that the compiler
does today explicitly. We mark them with "TODO: investigate cast".
Result: the compile becomes warning-free

2) go over all the "investigate cast" warnings, changing return
types/signatures where necessary. Result: our casts are now all kosher.

I'm happy to contribute the work for 1).

How does that sound?

https://codereview.appspot.com/557190043/