refactor: add LIFETIMEBOUND to blockfilter where needed #25967

1. 
   stickies-v commented at 1:56 pm on August 31, 2022: contributor

   Noticed from #25637 (comment) that BlockFilter::GetFilter() returns a reference to a member variable. Added LIFETIMEBOUND to all blockfilter-related code to ensure that the return values do not have a lifetime that exceeds the lifetime of what it is bound to. See https://github.com/bitcoin/bitcoin/blob/master/doc/developer-notes.md#lifetimebound or #25060 for a similar example.

   I used grep -E '[a-zA-Z>0-9][&*] ([a-zA-Z]*)\((.*)\)' src/**/blockfilter* to grep all possible occurrences (not all of them require LIFETIMEBOUND)

2. in src/index/blockfilterindex.h:55 in 60063f1564 outdated

   49@@ -49,9 +50,9 @@ class BlockFilterIndex final : public BaseIndex
   50 
   51     bool Rewind(const CBlockIndex* current_tip, const CBlockIndex* new_tip) override;
   52 
   53-    BaseIndex::DB& GetDB() const override { return *m_db; }
   54+    BaseIndex::DB& GetDB() const LIFETIMEBOUND override { return *m_db; }
   55 
   56-    const char* GetName() const override { return m_name.c_str(); }
   57+    const char* GetName() const LIFETIMEBOUND override { return m_name.c_str(); }
   

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   MarcoFalke commented at 2:10 pm on August 31, 2022:

   unrelated, as it requires a ton of changes, but it would be nice to change this to return a const std::string&

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   stickies-v commented at 3:54 pm on August 31, 2022:

   Agreed, I did a quick draft and it doesn’t seem like a big lift actually. Will follow up with PR shortly.

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   stickies-v commented at 11:27 am on September 1, 2022:

   Follow up in https://github.com/bitcoin/bitcoin/pull/25971
3. MarcoFalke approved
4. 
   MarcoFalke commented at 2:11 pm on August 31, 2022: member

   ACK. Seems unlikely that this would ever be used in a way to violate lifetimes, but adding the attribute can’t hurt.
5. DrahtBot added the label Refactoring on Aug 31, 2022
6. refactor: add LIFETIMEBOUND to blockfilter where needed

   Ensure that the return values do not have a lifetime that exceeds
   the lifetime of what it is bound to.
   See https://github.com/bitcoin/bitcoin/blob/master/doc/developer-notes.md#lifetimebound

   89576ccc57
7. stickies-v force-pushed on Aug 31, 2022
8. 
   stickies-v commented at 3:53 pm on August 31, 2022: contributor

   Rebase to fix CI failure - no other changes.
9. brunoerg approved
10. 
    brunoerg commented at 4:35 pm on August 31, 2022: contributor

    crACK 89576ccc572fcaf9fb7117ad6124482cc95fbd9f

    Coincidentally I was studying about LIFETIMEBOUND this morning. Nice catch!

11. MarcoFalke merged this on Sep 1, 2022
12. MarcoFalke closed this on Sep 1, 2022

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13. stickies-v deleted the branch on Sep 1, 2022
14. sidhujag referenced this in commit 502389d546 on Sep 1, 2022
15. MarcoFalke referenced this in commit 5eb9781763 on Sep 16, 2022
16. bitcoin locked this on Sep 1, 2023

Contributors
stickies-v MarcoFalke brunoerg

Labels
Refactoring