[tor-bugs] #29537 [Core Tor/Tor]: verify intptr_t round-trip through void *

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#29537: verify intptr_t round-trip through void *
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 Reporter:  catalyst                    |          Owner:  (none)
     Type:  defect                      |         Status:  needs_revision
 Priority:  Medium                      |      Milestone:  Tor:
                                        |  0.4.1.x-final
Component:  Core Tor/Tor                |        Version:
 Severity:  Normal                      |     Resolution:
 Keywords:  portability technical-debt  |  Actual Points:
Parent ID:                              |         Points:
 Reviewer:  catalyst, teor              |        Sponsor:
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Comment (by teor):

 Replying to [comment:17 rl1987]:
 > Are we doing the right thing here though? Intuitively, if we're writing
 code that a compiler might very reasonably optimize away, aren't we on a
 wrong path?

 Some of our existing code relies on behaviour that's not guaranteed by the
 standard. This ticket is about writing tests to make sure that our
 supported architectures do what we expect with this existing code. (Rather
 than changing pointer values in other ways.)

 See the ticket description for details.

 But these tests won't be any good to us if the casts are optimised away by
 the compiler. Much of our existing code avoids this optimisation by doing
 the casts in different functions in different modules. So the tests need
 to do the casts in different functions in a different module.

 > Perhaps we should create tickets to fix parts of tor codebase that rely
 on putting integers into `void *` one by one?

 We already have #23714 to fix these issues. But we want to add a test now,
 and do the fixes later.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/29537#comment:18>
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