Not that it is a huge deal either way, but I'd think it is harder for the
compiler to optimize across a function call boundary like memset() vs. a
struct initialization in the same function where it can see that all but
a few of the fields are being overwritten immediately before they are used.
I don't think the designated initializer is any less clear to the reader
that the struct is zeroed out compared to using memset(). Possibly the
best compromise is to use a designated initializer that specifies all of
the known fields, and leaves it to the compiler to initialize unset fields