This change assigns the type of the rhs expression to the variable that
will become a reference, as well as preventing clobbering of the rhs if
it is an already-typed variable.
Fixes: #2077
This change makes it possible to assign mixed expressions to variables
if an annotation is explicitly added to the variable. This allows the
use of `call_user_func` without needing to suppress issues.
Fixes: #1374
* Rewriting and streamlining every unit test with data providers.
All unit tests have been rewritten into PHPUnit data providers
to reduce the amount of unnecessary code-reuse through out the
test suite.
