scripted-diff: Use the C++11 keyword nullptr to denote the pointer literal instead of the macro NULL #10483

1. 
   practicalswift commented at 8:03 am on May 31, 2017: contributor

   Since C++11 the macro NULL may be:

   • an integer literal with value zero, or
   • a prvalue of type std::nullptr_t

   By using the C++11 keyword nullptr we are guaranteed a prvalue of type std::nullptr_t.

   For a more thorough discussion, see “A name for the null pointer: nullptr” (Sutter & Stroustrup), http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2431.pdf

   With this patch applied there are no NULL macro usages left in the repo:

   0$ git grep NULL -- "*.cpp" "*.h" | egrep -v '(/univalue/|/secp256k1/|/leveldb/|_NULL|NULLDUMMY|torcontrol.*NULL|NULL cert)' | wc -l
   10
   

   The road towards nullptr (C++11) is split into two PRs:

   • NULL → nullptr is handled in PR #10483 (scripted, this PR)
   • 0 → nullptr is handled in PR #10645 (manual)
2. fanquake added the label Refactoring on May 31, 2017
3. 
   jonasschnelli commented at 8:37 am on May 31, 2017: contributor

   Concept ACK
4. dcousens approved
5. 
   dcousens commented at 8:53 am on May 31, 2017: contributor

   utACK
6. 
   laanwj commented at 8:27 am on June 1, 2017: member

   Concept ACK. I think we can all agree that this needs to be done at some point, though we’ll have to discuss when to do this with the least impact. This change probably means every single PR needs to be rebased.
7. practicalswift force-pushed on Jun 4, 2017
8. 
   practicalswift commented at 4:53 pm on June 4, 2017: contributor

   Rebased!
9. 
   sipa commented at 6:20 pm on June 4, 2017: member

   Can you rewrite this as a series of scripted diffs (possibly mixed with a few manual commits to fix things up)? See #10189 #10193 #10502 #10321 for examples.

   As for timing, possibly immediately after the feature freeze?

10. practicalswift force-pushed on Jun 8, 2017
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20. 
    practicalswift commented at 2:29 pm on June 8, 2017: contributor

    @sipa Great idea! Now re-implemented as a scripted-diff. Looks good? :-)
21. practicalswift renamed this:
    Use the C++11 keyword nullptr to denote the pointer literal instead of the macro NULL
    scripted-diff: Use the C++11 keyword nullptr to denote the pointer literal instead of the macro NULL
    on Jun 8, 2017
22. 
    sipa commented at 8:12 pm on June 8, 2017: member

    @practicalswift You can use sed -i 's/\<NULL\>/nullptr/g' for the main operation. \< and \> denote begin and end of word.
23. practicalswift force-pushed on Jun 9, 2017
24. 
    practicalswift commented at 3:26 pm on June 9, 2017: contributor

    @sipa Good point! Now using s/\<NULL\>/nullptr/g. Looks good? :-)
25. practicalswift force-pushed on Jun 11, 2017
26. practicalswift force-pushed on Jun 11, 2017
27. 
    practicalswift commented at 1:53 pm on June 11, 2017: contributor

    Merge conflicts resolved!
28. 
    practicalswift commented at 9:23 am on June 13, 2017: contributor

    What is the correct protocol to follow w.r.t. rebasing a large scripted-diff PR such as this one?

    Should I rebase periodically myself to keep it mergeable, or should I wait until I’m asked to rebase prior to the suggested time for merge (@sipa suggested: “possibly immediately after the feature freeze”).

29. 
    MarcoFalke commented at 10:20 am on June 13, 2017: member

    @practicalswift It is sufficient to rebase only once. Please refer to #9961#issue-212976673 for the preliminary date of feature freeze.
30. 
    practicalswift commented at 10:36 am on June 13, 2017: contributor

    @MarcoFalke Great! Thanks for clarifying!
31. 
    theuni commented at 8:54 pm on June 13, 2017: member

    Concept ACK. It’d be helpful to compare before/after binaries.
32. practicalswift force-pushed on Jun 14, 2017
33. practicalswift force-pushed on Jun 18, 2017
34. 
    jtimon commented at 1:24 am on June 22, 2017: contributor

    utACK But after revieweing the code, the script seems to be more complicated than it needs to be, wouldn’t the following do the same?

    0sed -i 's/NULL/nullptr/g' ./src/*.h ./src/*.cpp ./src/*/*.h ./src/*/*.cpp ./src/*/*/*.h ./src/*/*/*.cpp ;
    

35. 
    practicalswift commented at 2:17 am on June 22, 2017: contributor

    @jtimon Unfortunately that command is a bit too broad which leads to the following problems:

    • It would match dependencies such as src/leveldb/, src/secp256k1/, src/univalue/, etc.
    • It would match unrelated constants such as TX_NULL_DATA, SCRIPT_VERIFY_NULLDUMMY, SCRIPT_VERIFY_NULLFAIL, bitcoinconsensus_SCRIPT_FLAGS_VERIFY_NULLDUMMY, SCRIPT_ERR_SIG_NULLDUMMY, SCRIPT_ERR_SIG_NULLFAIL, etc.
36. practicalswift force-pushed on Jun 22, 2017
37. 
    jtimon commented at 9:04 pm on June 23, 2017: contributor

    What about ?

    0sed -i 's/ NULL/ nullptr/g' ./src/*.h ./src/*.cpp ./src/*/*.h ./src/*/*.cpp ./src/*/*/*.h ./src/*/*/*.cpp ;
    1sed -i 's/ nullptr/ NULL/g' ./src/leveldb/*.*  ./src/secp256k1/.*.*;
    

    Anyway, no big deal, probably not worth it to change it. I looked at the changes and they do what I expect.

38. 
    practicalswift commented at 7:30 am on June 26, 2017: contributor

    @jtimon Unfortunately that one is too broad – it will replace NULLDUMMY with nullptrDUMMY, etc. 's/\<NULL\>/nullptr/g' is the narrowest replacement I can think of :-)
39. 
    jtimon commented at 1:59 am on June 27, 2017: contributor

    No worries, what you have seems to work. Needs rebase.
40. practicalswift force-pushed on Jun 27, 2017
41. 
    practicalswift commented at 5:17 am on June 27, 2017: contributor

    Rebased! :-)
42. practicalswift force-pushed on Jun 28, 2017
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44. practicalswift force-pushed on Jul 15, 2017
45. 
    practicalswift commented at 1:00 pm on July 15, 2017: contributor

    Rebased!
46. 
    TheBlueMatt commented at 7:44 pm on July 16, 2017: member

    utACK 2f2ac6fc76c966b6174d9df647648d0573d2ac41. I read through the diff but not thoroughly, the script looks good :).
47. practicalswift force-pushed on Jul 17, 2017
48. 
    practicalswift commented at 8:00 am on July 17, 2017: contributor

    Rebased! :-)
49. 
    jtimon commented at 1:23 am on July 18, 2017: contributor

    Fast scroll-down re-review ACK. Didn’t checked the rebase.
50. practicalswift force-pushed on Jul 24, 2017
51. laanwj added this to the milestone 0.15.0 on Jul 28, 2017
52. practicalswift force-pushed on Aug 1, 2017
53. 
    practicalswift commented at 5:05 pm on August 1, 2017: contributor

    Rebased! :-)
54. 
    promag commented at 3:17 pm on August 6, 2017: member

    utACK 2f2ac6f.

    Nit, while rebasing, reword to something short, like scripted-diff: Replace NULL macro with C++11 nullptr keyword.

55. 
    sipa commented at 10:08 pm on August 6, 2017: member

    Let’s try to merge this right before branching off 0.15.
56. scripted-diff: Use the C++11 keyword nullptr to denote the pointer literal instead of the macro NULL

    -BEGIN VERIFY SCRIPT-
    sed -i 's/\<NULL\>/nullptr/g' src/*.cpp src/*.h src/*/*.cpp src/*/*.h src/qt/*/*.cpp src/qt/*/*.h src/wallet/*/*.cpp src/wallet/*/*.h src/support/allocators/*.h
    sed -i 's/Prefer nullptr, otherwise SAFECOOKIE./Prefer NULL, otherwise SAFECOOKIE./g' src/torcontrol.cpp
    sed -i 's/tor: Using nullptr authentication/tor: Using NULL authentication/g' src/torcontrol.cpp
    sed -i 's/METHODS=nullptr/METHODS=NULL/g' src/test/torcontrol_tests.cpp src/torcontrol.cpp
    sed -i 's/nullptr certificates/NULL certificates/g' src/qt/paymentserver.cpp
    sed -i 's/"nullptr"/"NULL"/g' src/torcontrol.cpp src/test/torcontrol_tests.cpp
    -END VERIFY SCRIPT-

    90d4d89230
57. practicalswift force-pushed on Aug 7, 2017
58. 
    practicalswift commented at 5:38 am on August 7, 2017: contributor

    Rebased! @sipa That’s great! When is that expected to happen? I’ll keep this PR rebased :-)
59. 
    practicalswift commented at 5:42 am on August 7, 2017: contributor

    What about merging the related PR #10645 (“Use nullptr (C++11) instead of zero (0) as the null pointer constant “) at the same time? :-)
60. 
    MarcoFalke commented at 1:03 pm on August 8, 2017: member

    90d4d89 conflicts with #10882, which is tagged for 0.15.
61. 
    practicalswift commented at 1:42 pm on August 8, 2017: contributor

    @MarcoFalke Thanks for the notification! Should I wait until #10882 is merged and then rebase on master or what is the preferred way to handle it?
62. laanwj merged this on Aug 14, 2017
63. laanwj closed this on Aug 14, 2017

    ---

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65. 
    practicalswift commented at 2:35 pm on August 14, 2017: contributor

    @laanwj Excellent! Thanks for merging! :-)
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Contributors
practicalswift jonasschnelli dcousens laanwj sipa MarcoFalke theuni jtimon TheBlueMatt promag

Labels
Refactoring

Milestone
0.15.0