bench/test: clarify merkle bench and witness test intent #34376

1. 
   l0rinc commented at 10:31 pm on January 21, 2026: contributor

   Follow-up to #32497.

   Clarify why the witness merkle test uses an odd leaf count (it exercises leaf duplication in ComputeMerkleRoot()), and make the coinbase witness hash initialization explicit.

   Also simplify the leaf-copy loop in the MerkleRoot benchmark for readability.

   No production code is changed in this follow-up, for simplicity and safety.

2. bench/test: clarify merkle bench and witness test intent

   Follow-up to bitcoin/bitcoin#32497.
   
   Clarify why the witness merkle test uses an odd leaf count (it exercises leaf duplication in `ComputeMerkleRoot()`), and make the coinbase witness hash initialization explicit.
   
   Also simplify the leaf-copy loop in the MerkleRoot benchmark for readability.
   
   No production code is changed in this follow-up, for simplicity and safety.
   
   Co-authored-by: w0xlt <94266259+w0xlt@users.noreply.github.com>

   8b9d30e3fa
3. 
   DrahtBot commented at 10:31 pm on January 21, 2026: contributor

   The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

   Code Coverage & Benchmarks

   For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/34376.

   Reviews

   See the guideline for information on the review process.

   Type	Reviewers
   ACK	w0xlt, optout21, danielabrozzoni, maflcko, achow101

   If your review is incorrectly listed, please copy-paste <!–meta-tag:bot-skip–> into the comment that the bot should ignore.

4. 
   w0xlt commented at 11:43 pm on January 21, 2026: contributor

   ACK https://github.com/bitcoin/bitcoin/pull/34376/commits/8b9d30e3facff0cd132dc3faf6282d75b1f9b532
5. 
   optout21 commented at 5:10 am on January 22, 2026: contributor

   ACK 8b9d30e3facff0cd132dc3faf6282d75b1f9b532

   • only minor changes
   • test code only
   • a followup
6. danielabrozzoni approved
7. 
   danielabrozzoni commented at 1:35 pm on January 22, 2026: member

   tACK 8b9d30e3facff0cd132dc3faf6282d75b1f9b532
8. 
   maflcko commented at 5:49 pm on January 22, 2026: member

   lgtm ACK 8b9d30e3facff0cd132dc3faf6282d75b1f9b532
9. 
   achow101 commented at 9:34 pm on January 22, 2026: member

   ACK 8b9d30e3facff0cd132dc3faf6282d75b1f9b532
10. achow101 merged this on Jan 22, 2026
11. achow101 closed this on Jan 22, 2026

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Contributors
l0rinc DrahtBot w0xlt optout21 danielabrozzoni maflcko achow101