doc: Fix missing cmake -B option in fuzzing quickstart guide #34876

1. 
   ekzyis commented at 9:49 am on March 20, 2026: none

   cmake --build assumes our build directory is build_fuzz, but cmake didn’t use -B build_fuzz, so simply copying and pasting the commands didn’t work.
2. doc: Fix missing cmake -B option in fuzzing quickstart guide c70bab28c7
3. DrahtBot added the label Docs on Mar 20, 2026
4. 
   DrahtBot commented at 9:50 am on March 20, 2026: contributor

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5. ekzyis renamed this:
   doc: Fix missing -B option for cmake in fuzzing quickstart guide
   doc: Fix missing cmake -B option in fuzzing quickstart guide
   on Mar 20, 2026
6. 
   maflcko commented at 10:36 am on March 20, 2026: member

   I don’t understand this. The preset literally has it set to that:

   0      "binaryDir": "${sourceDir}/build_fuzz",
   

7. 
   maflcko commented at 10:37 am on March 20, 2026: member

   What is the output before and after the changes here?
8. 
   hebasto commented at 12:00 pm on March 20, 2026: member

   cmake --build assumes our build directory is build_fuzz, but cmake didn’t use -B build_fuzz…

   It does:https://github.com/bitcoin/bitcoin/blob/6e295d8ad5fff4dc07519f570e9a04ac57ecb639/CMakePresets.json#L41

9. 
   ekzyis commented at 3:01 pm on March 20, 2026: none

   Oh, I just checked my bash history. I did not actually copy and paste the commands. :sweat_smile:

   I manually edited my cmake command for clean rebuilds to include --preset=libfuzzer and --build build_fuzz instead of --build build:

   0$ rm -rf build && cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=1 --preset=libfuzzer -B build && cmake --build build_fuzz -j8
   

   This obviously did not create build_fuzz, but build.

   When I run cmake --preset=libfuzzer, like in the documentation, it does create build_fuzz.

   Sorry! I was too quick to assume inconsistent documentation and push a fix. Should have looked into --preset first.

   I guess I’m too used to inconsistent documentation (in other projects) haha :sweat_smile:

10. ekzyis closed this on Mar 20, 2026

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11. ekzyis deleted the branch on Mar 20, 2026

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