• epriestley's avatar
    Set "history.immutable" to "false" explicitly in .arcconfig · 182a1462
    epriestley authored
    Summary:
    If contributors use "history.immutable" by default (for example, in user/global config) and then try to contribute to Phabricator, they might land in a way that creates merge commits, which we'd prefer to avoid.
    
    To make this a bit harder to do unintentionally, set "history.immutable" to "false" explicitly in `.arcconfig`. This will override any user or system setting and keep `land` in squash mode in this project.
    
    This might also be a problem in general, and maybe in the long term we need something like one of these warnings:
    
    > (when arc landing) You haven't landed changes to this project before, are you sure you want to create a merge commit / are you sure you want to squash?
    
    ...or:
    
    > (when doing anything) This project doesn't have a history.immutable setting; you should probably set one so user settings don't win out.
    
    ...or just not let this be set at the user/system level, although that's annoying in some cases. Also maybe this:
    
    > (when arc landing) You're about to create a merge commit, but the last Differential change in history squashed instead. Merge anyway?
    
    However, we haven't seen this as a widespread issue outside of this project yet (and even in this project I think it has only happened 2-3 times), so just put up a guard rail in our own configuration for now.
    
    Test Plan:
      - Ran `arc set-config history.immutable true` to set the flag in my user settings.
      - Ran `arc get-config` to verify that the setting overrode system/user settings:
    
    ```
    epriestley@orbital ~/dev/phabricator $ arc get-config history.immutable --verbose
    history.immutable
    
        If true, arc will never change repository history (e.g., through amending
        or rebasing). Defaults to true in Mercurial and false in Git. This
        setting has no effect in Subversion.
    
           Example Value: false
    
           Current Value: false
          Current Source: project
    
             local Value: -
           project Value: false
              user Value: true
            system Value: -
           default Value: -
    ```
    
    Reviewers: chad, fooishbar
    
    Reviewed By: fooishbar
    
    Differential Revision: https://secure.phabricator.com/D16364
    182a1462