On Sun, Dec 22, 2019 at 11:48 AM Jon Kalb via SG20 <sg20@lists.isocpp.org> wrote:

There are two cases, what Herb calls “tracking” and “making the type stick.” I think I’d call them “tracking” and “fixing.” I think they should be spelled:

auto x{expr}; // tracking - we want x to be whatever expr returns, even if it is changed by maintenance

The callee decides the type.
auto x{type{expr}}; // fixing - we want x to be type regardless of what expr returns.

The caller decides the type.

I don’t see any other case.

The case that isn't here is the no surprises case when you want the caller type and the callee type to match an explicitly mentioned type.
 Nevin ":-)" Liber  <mailto:nevin@cplusplusguy.com>  +1-847-691-1404