Allow git config to append a comment after a newly-added/-set/-replaced value

[dscho]

It is all nice and good to be able to call git config this.that something to configure something programmatically, but there is no way to leave a comment right now. It would be nice to say something like git config --comment="I added this. -- banksy" this.that something and end up with a config containing this:

[this]
  that = something # I added this. -- banksy

To accomplish this, one would need to:

• modify the write_pair() function, adding another function parameter (const char *comment?) that is then also appended to &sb, if non-NULL
• modify the function signature of git_config_set_multivar_in_file_gently() to accept the same parameter, adjusting all its callers to simply pass NULL
• pass this parameter in the two callers of write_pair() in the git_config_set_multivar_in_file_gently() function (#1, #2
• append a new file-local variable to builtin/config.c's list of file-local variables and add a command-line option to git config's, then ensuring that cmd_config() verifies that this option is only used in conjunction with ACTION_SET_ALL, ACTION_ADD or ACTION_REPLACE_ALL, otherwise error out with an error message
• modify cmd_config() to pass the comment to git_config_set_multivar_in_file_gently() when setting/adding/replacing (#1, #2, #3; there are two more callers, but they are unsetters)
• document the option in Documentation/git-config.txt
• add a test case to t/t1300-config.sh.

See also https://discord.com/channels/1042895022950994071/1213052410281467906/1213052410281467906

[rseichter]

Thank you for taking the time to write up this issue. I didn't expect my question in Discord and our subsequent brief discussion to lead us here, but surprises do happen. 😉

[rseichter]

@dscho I took my first baby steps in #1681. Your hints were very useful, and I only made modifications in a small number of additional places the compiler complained about. My manual tests worked, but before I invest more time in updating docs and the Git test suite, I'd like to hear your take on the changes I made so far. Cheers.

[LemmingAvalanche]

PR closed since this is in master 3256584 (Merge branch 'rs/config-comment', 2024-04-05)

I guess this can be closed?