build: install shell completions via cmake #34721

1. 
   willcl-ark commented at 2:33 pm on March 3, 2026: member

   Fixes: #34714

   Packagers currently need to manually copy shell completion scripts from contrib/completions/ into the appropriate system directories.

   Install bash and fish completions alongside their corresponding binaries as part of install_binary_component(), following the same pattern used for man pages. Completion files are automatically detected per component and installed to the standard locations:

   • bash: ${datadir}/bash-completion/completions/
   • fish: ${datadir}/fish/vendor_completions.d/

   Enabled by default. Can be disabled with -DINSTALL_COMPLETIONS=OFF. (This matches INSTALL_MAN default)

2. build: install shell completions via cmake

   Packagers currently need to manually copy shell completion scripts
   from contrib/completions/ into the appropriate system directories.
   
   Install bash and fish completions alongside their corresponding
   binaries as part of install_binary_component(), following the same
   pattern used for man pages. Completion files are automatically
   detected per component and installed to the standard locations:
   - bash: ${datadir}/bash-completion/completions/
   - fish: ${datadir}/fish/vendor_completions.d/
   
   Enabled by default. Can be disabled with -DINSTALL_COMPLETIONS=OFF.

   0a2d2cd116
3. DrahtBot added the label Build system on Mar 3, 2026
4. 
   DrahtBot commented at 2:33 pm on March 3, 2026: contributor

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

   Reviews

   See the guideline for information on the review process.

   Type	Reviewers
   Concept ACK	w0xlt, hebasto, caesrcd, BrandonOdiwuor

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

5. 
   kpcyrd commented at 3:28 pm on March 3, 2026: none

   I tested this patch and it works well for me :smiley_cat:
6. DrahtBot added the label CI failed on Mar 3, 2026
7. 
   w0xlt commented at 3:52 pm on March 3, 2026: contributor

   Concept ACK
8. 
   hebasto commented at 3:57 pm on March 3, 2026: member

   Concept ACK.
9. 
   fanquake commented at 4:08 pm on March 3, 2026: member

   Will we start maintaining these, if we plan on installing them? #33747, #33402, #33385. There doesn’t seem to be any interest historically from contributors.
10. DrahtBot removed the label CI failed on Mar 3, 2026
11. 
    willcl-ark commented at 11:45 am on March 4, 2026: member

    Will we start maintaining these, if we plan on installing them?

    Fair shout. The alternative is to not maintain them and but to then also not ship them at all. My preference would be to maintain and install them.

    I have reviewed #33385 as I think this looks in the best shape to move forward, barring author response time.

12. 
    caesrcd commented at 6:30 pm on March 4, 2026: none

    Concept ACK
13. in CMakeLists.txt:180 in 0a2d2cd116

    176@@ -177,6 +177,7 @@ option(BUILD_FUZZ_BINARY "Build fuzz binary." OFF)
    177 option(BUILD_FOR_FUZZING "Build for fuzzing. Enabling this will disable all other targets and override BUILD_FUZZ_BINARY." OFF)
    178 
    179 option(INSTALL_MAN "Install man pages." ON)
    180+option(INSTALL_COMPLETIONS "Install shell completion scripts." ON)
    

    ---

    ---

    

    luke-jr commented at 7:09 am on March 10, 2026:

    Users are at least somewhat unlikely to use multiple shells, so it probably makes sense to have a separate option for each one
14. 
    purpleKarrot commented at 9:45 am on March 10, 2026: contributor

    I don’t like the direction the install_binary_component command is evolving. My concerns are:

    • if(EXISTS ${...}): The problem is that adding a file may change the behavior of install, but only after cmake was manually rerun. Adding the file will not trigger the reconfiguration by itself. This leads to flakiness (similar to file(GLOB)). CMakeLists.txt files should always explicitly describe the source tree. Things like if(EXISTS) and file(GLOB) should be reserved for cmake -P scripts.

    • option(INSTALL_COMPLETIONS): This is a build option, that does not affect the build, hence the wrong tool for the job (so is INSTALL_MAN). Better: Use fine grained install components, to let the user decide at install time what to install. The 1:1 relationship of target and component is not helpful.

    The whole install_binary_component command should be inlined at the call sites and then removed. This makes the CMakeLists.txt much more declarative:

    • For targets that are installed to the default location, don’t specify the location but use the default.
    • For targets that have manpages and shell completions, install them. For targets that don’t, just don’t.

    Any “convenience” wrapper should be killed before it attracts more and more responsibilities.

15. 
    BrandonOdiwuor commented at 8:23 am on March 11, 2026: contributor

    Concept ACK

    Installing shell completions automatically with cmake --install is more convenient. Tested on Ubuntu 24.04 with bash.

    –prefix and –component install

Contributors
willcl-ark DrahtBot kpcyrd w0xlt hebasto fanquake caesrcd luke-jr purpleKarrot BrandonOdiwuor

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