Feature request:
Make it possible to tell mypy to treat the following as errors:

if None:
    pass
if 1:
    pass
if [1, 2, 3]:
    pass
if "asdf":
    pass

class A:
    def __bool__(self):
        return True
a = A()
if a:
    pass

(This list is based on the "Truth Value Testing" section in https://docs.python.org/3/library/stdtypes.html)

The goal is to force the developer to use explicit coercions like:

if x is not None:
    pass
if x != 0:
    pass
if len(x) > 0:
    pass
if bool(x):
    pass

Of course libraries and stubs should not be affected by this restriction.

The rationale is that while truth value testing is a valuable shortcut for many people, it also causes bugs, so some projects might want to force their developers to use explicit coercions.