cmake: Fail if `Libmultiprocess` is missing when `WITH_MULTIPROCESS=ON` #31709

1. 
   hebasto commented at 5:35 PM on January 22, 2025: member

   Fixes #31708:

   $ cmake -B build -DWITH_MULTIPROCESS=ON
   -- The CXX compiler identification is GNU 13.3.0
   -- Detecting CXX compiler ABI info
   -- Detecting CXX compiler ABI info - done
   -- Check for working CXX compiler: /usr/bin/c++ - skipped
   -- Detecting CXX compile features
   -- Detecting CXX compile features - done
   -- Found SQLite3: /usr/include (found suitable version "3.45.1", minimum required is "3.7.17") 
   CMake Error at CMakeLists.txt:146 (find_package):
     By not providing "FindLibmultiprocess.cmake" in CMAKE_MODULE_PATH this
     project has asked CMake to find a package configuration file provided by
     "Libmultiprocess", but CMake did not find one.
   
     Could not find a package configuration file provided by "Libmultiprocess"
     with any of the following names:
   
       LibmultiprocessConfig.cmake
       libmultiprocess-config.cmake
   
     Add the installation prefix of "Libmultiprocess" to CMAKE_PREFIX_PATH or
     set "Libmultiprocess_DIR" to a directory containing one of the above files.
     If "Libmultiprocess" provides a separate development package or SDK, be
     sure it has been installed.
   
   
   -- Configuring incomplete, errors occurred!
   

2. cmake: Fail if `Libmultiprocess` is missing when `WITH_MULTIPROCESS=ON` c31166ac77
3. 
   DrahtBot commented at 5:35 PM on January 22, 2025: contributor

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   Code Coverage & Benchmarks

   For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/31709.

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4. DrahtBot added the label Build system on Jan 22, 2025
5. hebasto added this to the milestone 29.0 on Jan 22, 2025
6. vasild approved
7. 
   vasild commented at 6:00 PM on January 22, 2025: contributor

   ACK c31166ac77af8fbdc9012999b345540fe88cc394

   I just encountered the current behavior in master today. It wasn't unmanageable because the error message is quite clear. Anyway I agree it is better to flag the library as required which turns the warning into an error:

   @@ -1,23 +1,18 @@
   -CMake Warning at CMakeLists.txt:146 (find_package):
   +CMake Error at CMakeLists.txt:146 (find_package):
      By not providing "FindLibmultiprocess.cmake" in CMAKE_MODULE_PATH this
      project has asked CMake to find a package configuration file provided by
      "Libmultiprocess", but CMake did not find one.
    
      Could not find a package configuration file provided by "Libmultiprocess"
      with any of the following names:
    
        LibmultiprocessConfig.cmake
        libmultiprocess-config.cmake
    
      Add the installation prefix of "Libmultiprocess" to CMAKE_PREFIX_PATH or
      set "Libmultiprocess_DIR" to a directory containing one of the above files.
      If "Libmultiprocess" provides a separate development package or SDK, be
      sure it has been installed.
   -
   -
   --- Could NOT find LibmultiprocessNative (missing: LibmultiprocessNative_DIR)
   -CMake Error at src/ipc/CMakeLists.txt:12 (target_capnp_sources):
   -  Unknown CMake command "target_capnp_sources".
    
    
    -- Configuring incomplete, errors occurred!
   

8. ryanofsky approved
9. 
   ryanofsky commented at 6:13 PM on January 22, 2025: contributor

   Code review ACK c31166ac77af8fbdc9012999b345540fe88cc394

10. sedited approved
11. 
    sedited commented at 7:44 AM on January 23, 2025: contributor

    ACK c31166ac77af8fbdc9012999b345540fe88cc394

12. fanquake merged this on Jan 23, 2025
13. fanquake closed this on Jan 23, 2025

    ---

14. hebasto deleted the branch on Jan 23, 2025
15. sedited referenced this in commit e1405325c9 on Feb 3, 2025
16. stickies-v referenced this in commit d760fd3dda on Mar 17, 2025
17. stickies-v referenced this in commit cc83553352 on Mar 17, 2025
18. stickies-v referenced this in commit 2614933f06 on Mar 17, 2025
19. stickies-v referenced this in commit b70418c5fc on Mar 17, 2025
20. stickies-v referenced this in commit 69f8a1fe50 on Mar 17, 2025
21. bug-castercv502 referenced this in commit bf2e6853b0 on Sep 28, 2025
22. bitcoin locked this on Jan 23, 2026

Milestone
29.0