No, they don’t. They did in Python 2—list comps were introduced in 2.0, genexps in 2.4, and set/dict comps in 3.0 but also included in the later 2.7 release—but that’s been non-current for more than a decade, and conpletely out of support for two years. Let it go.

> But, backwards compatibility aside, the language could change to make for-loops behave like sequence comprehensions wrt scoping.

Sure in Python 4, but after 2->3, not sure many people are looking forward to that.

   Python 3.10.5 (tags/v3.10.5:f377153, Jun  6 2022, 16:14:13) [MSC v.1929 64 bit (AMD64)] on win32
   Type "help", "copyright", "credits" or "license" for more information.
   >>> [f() for f in [lambda: i for i in range(0, 10)]]
   [9, 9, 9, 9, 9, 9, 9, 9, 9, 9]
   >>> [f() for f in (lambda: i for i in range(0, 10))]
   [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

If you instead fully evaluate the generator expression before calling any of the functions (for example, by passing it to the list constructor), you get the same behavior as the list comprehension case:

    >>> [f() for f in list(lambda: i for i in range(0, 10))]
    [9, 9, 9, 9, 9, 9, 9, 9, 9, 9]

Side note: I think that commenters above didn't quite understand what I meant by "leaking", because there's more than one scope boundary here. Roughly speaking, any comprehension or loop can be desugared into something that looks like a C-style for-loop:

   /* scope 1 */
   for (/* scope 2 */) {
      /* scope 3 */
   }