While committing issue bpo-24129, I noticed the following in the execution model documentation:

==================
If a variable is referenced in an enclosing scope, it is illegal to delete the name. An error will be reported at compile time.
==================

I'm not sure what that means, as both of the following compiled fine for me under 3.4.2:

>>> def f():
...     x = 1
...     def g():
...         nonlocal x
...         del x
... 
>>> def f():
...     x = 1
...     del x
...     def g():
...         print(x)
...

Note that I haven't attempted to resolve this myself, as I'm not sure if we should just delete the paragraph, or if we accidentally dropped a compile time error check that didn't have any tests somewhere along the line.

Probably a good one to raise on python-dev...

I wonder if it is a left-over from the behaviour prior to 3.2? In 3.1, I
get this syntax error:

py> def outer():
... spam = 1
... def inner():
... nonlocal spam
... del spam
... inner()
...
SyntaxError: can not delete variable 'spam' referenced in nested scope

See also the "Changed in 3.2" comment here:

https://docs.python.org/3/reference/simple_stmts.html#the-del-statement

It looks like it is safe to just remove this line from docs. This code

>>> x = 1
>>> def f():
...     global x
...     del x
... 
>>> f()
>>> x

Works as expected, i.e. raises NameError. (The same happens for nonlocal but with UnboundLocalError.)

Thanks for the PR, Ivan. Merged and backported to 3.5 and 3.6.