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Re: [PATCH 1/9] Define a structure for object IDs.

From
David Kastrup <dak@gnu.org>
Date
May 5, 2014, 05:19 UTC
Message-ID
<87lhugu7iw.fsf@fencepost.gnu.org>
In-Reply-To
<87ppjt6xjv.fsf@igel.home>
Andreas Schwab <schwab@linux-m68k.org> writes:
Show 8 quoted lines
> Johannes Sixt <j6t@kdbg.org> writes:
>
>> Isn't internal padding only allowed between members to achieve correct
>> alignment of later members, and at the end only sufficient padding so
>> that members are aligned correctly when the struct is part of an array?
>
> The standard allows arbitrary internal padding, it doesn't have to be
> minimal.

What the standard does guarantee is that a pointer to a struct can be cast to a pointer to its first member and vice versa. It does not as far as I can see guarantee that a pointer to something of the same type of its first member can be converted to a pointer to a struct even if the struct only contains a member of such type.

-- 
David Kastrup
Previous: Andreas SchwabNext: Andreas Schwab
Message 9 of 39 in “Use a structure for object IDs.”
  1. 0/9 Use a structure for object IDs.brian m. carlson, May 3, 2014
  2. 1/9 Define a structure for object IDs.brian m. carlson, May 3, 2014
  3. Michael HaggertyMay 4, 2014
  4. Johannes SixtMay 4, 2014
  5. David KastrupMay 4, 2014
  6. Andreas SchwabMay 4, 2014
  7. Johannes SixtMay 4, 2014
  8. Andreas SchwabMay 4, 2014
  9. David KastrupMay 5, 2014
  10. Andreas SchwabMay 5, 2014
  11. James DenholmMay 5, 2014
  12. David KastrupMay 5, 2014
  13. Michael HaggertyMay 5, 2014
  14. Andreas SchwabMay 5, 2014
  15. David KastrupMay 5, 2014
  16. Felipe ContrerasMay 5, 2014
  17. Duy NguyenMay 4, 2014
  18. brian m. carlsonMay 4, 2014
  19. Andreas SchwabMay 4, 2014
  20. David KastrupMay 4, 2014
  21. Andreas SchwabMay 4, 2014
  22. David KastrupMay 4, 2014
  23. Andreas SchwabMay 4, 2014
  24. 2/9 bisect.c: convert to use struct object_idbrian m. carlson, May 3, 2014
  25. 3/9 archive.c: convert to use struct object_idbrian m. carlson, May 3, 2014
  26. 4/9 zip: use GIT_OID_HEXSZ for trailersbrian m. carlson, May 3, 2014
  27. 5/9 branch.c: convert to use struct object_idbrian m. carlson, May 3, 2014
  28. 6/9 bulk-checkin.c: convert to use struct object_idbrian m. carlson, May 3, 2014
  29. 7/9 bundle.c: convert leaf functions to struct object_idbrian m. carlson, May 3, 2014
  30. Michael HaggertyMay 6, 2014
  31. 8/9 cache-tree: convert struct cache_tree to use object_idbrian m. carlson, May 3, 2014
  32. Michael HaggertyMay 6, 2014
  33. Michael HaggertyMay 6, 2014
  34. 9/9 diff: convert struct combine_diff_path to object_idbrian m. carlson, May 3, 2014
  35. Michael HaggertyMay 6, 2014
  36. brian m. carlsonMay 3, 2014
  37. Michael HaggertyMay 4, 2014
  38. Johannes SixtMay 4, 2014
  39. brian m. carlsonMay 4, 2014

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