Coverity complained about the call to warnNullCallable() being dead
code for most instantiations of the create() function template. It's
right, of course, even though warning in a template that clearly has
instantations where it's not dead code isn't exactly helpful.
Nonetheless, take the opportinity to avoid the dead code warning at
the expense of a bit or un-DRY-ing:
- because we now use them more than once, cache the result of
is_*function_* predicates in constexpr variables
- then scope the is_null variable such that its use is not subject to
dead-code removal anymore (at instantiation time; it may still be
removed by the optimizer)
As drive-bys, add a comment about the reinterpret_cast, and make the
custom template predicates variable- instead of class templates.
Coverity-Id: 407640
Change-Id: I272223042c2aae9d814e82c466e1d29e1c42bfa1
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
6da9662143