pcottle/learnGitBranching · warning · GitError

hg-error-log-no-follow

Error message

hg-error-log-no-follow

What it means

In mercurial mode, `hg log` is only implemented as a delegation to the git log machinery after rewriting '.' to HEAD, and that delegation requires the -f (follow) option. Without -f the command throws a GitError with 'hg-error-log-no-follow'.

Source

Thrown at src/js/mercurial/commands.js:80

      return {
        vcs: 'git',
        name: 'cherrypick'
      };
    }
  },

  log: {
    regex: /^hg +log($|\s)/,
    options: [
      '-f'
    ],
    dontCountForGolf: true,
    delegate: function(engine, command) {
      var options = command.getOptionsMap();
      command.acceptNoGeneralArgs();

      if (!options['-f']) {
        throw new GitError({
          msg: intl.str('hg-error-log-no-follow')
        });
      }
      command.mapDotToHead();
      return {
        vcs: 'git',
        name: 'log'
      };
    }
  },

  bookmark: {
    regex: /^hg (bookmarks|bookmark|book)($|\s)/,
    options: [
      '-r',
      '-f',
      '-d'
    ],

View on GitHub (pinned to 5b09d0ff96)

Solutions

1. Run `hg log -f` instead of bare `hg log`
2. Check your level's expected solution commands if a scripted flow fails here
3. Remember this is a simulation limitation, not real hg behavior

Example fix

// before
hg log
// after
hg log -f

const m = cmd.match(/^hg +log(.*)$/);
if (m && !/(^|\s)-f(\s|$)/.test(m[1])) { inform('use hg log -f'); }

try { run('hg log'); } catch (e) { if (e instanceof GitError) { suggest('hg log -f'); } else throw e; }

When it happens

Trigger: Running `hg log` without the `-f` flag in hg mode. `command.getOptionsMap()` is inspected; if options['-f'] is falsy the error is raised before `mapDotToHead()` and delegation occur.

Common situations: Users habitually typing `hg log` bare as in real Mercurial; porting git-mode lesson flows (`git log`) to hg mode where follow is mandatory in this simulation.

Related errors

• hg-error-no-status
• -m and -d are incompatible
• -r is incompatible with -d
• -r is incompatible with -m
• git-error-options

AI-assisted analysis of pcottle/learnGitBranching@5b09d0ff96 (2026-08-27). Data as JSON: /api/errors/397469b951ba4175. Report an issue: GitHub.