What causes "the branch to compare '%s' is the same as --base" in mislav/hub?

Pass a different branch as the compare target than the one given to --base.

the branch to compare '%s' is the same as --base

Error message

the branch to compare '%s' is the same as --base

What it means

In commands/compare.go compare, after resolving the target branch r (possibly namespaced as owner:branch), it checks whether r equals the --base value. Identical base and compare branches would produce an empty range, so the command fails with "the branch to compare '%s' is the same as --base".

Source

Thrown at commands/compare.go:108

		if err != nil {
			if remoteProject, err = deducePushTarget(currentBranch, host.User); err == nil {
				remoteBranch = currentBranch
			} else {
				utils.Check(fmt.Errorf("the current branch '%s' doesn't seem pushed to a remote", currentBranch.ShortName()))
			}
		}

		r = remoteBranch.ShortName()
		if remoteProject.SameAs(mainProject) {
			if flagCompareBase == "" && remoteBranch.IsMaster() {
				utils.Check(fmt.Errorf("the branch to compare '%s' is the default branch", remoteBranch.ShortName()))
			}
		} else {
			r = fmt.Sprintf("%s:%s", remoteProject.Owner, r)
		}

		if flagCompareBase == r {
			utils.Check(fmt.Errorf("the branch to compare '%s' is the same as --base", r))
		} else if flagCompareBase != "" {
			r = fmt.Sprintf("%s...%s", flagCompareBase, r)
		}
	} else {
		if flagCompareBase != "" {
			utils.Check(command.UsageError(""))
		} else {
			r = parseCompareRange(args.RemoveParam(args.ParamsSize() - 1))
			if !args.IsParamsEmpty() {
				owner := args.RemoveParam(args.ParamsSize() - 1)
				mainProject = github.NewProject(owner, mainProject.Name, mainProject.Host)
			}
		}
	}

	url := mainProject.WebURL("", "", "compare/"+rangeQueryEscape(r))

	args.NoForward()

View on GitHub (pinned to 5c547ed804)

Solutions

Pass a different branch as the compare target than the one given to --base.
Remove `--base` if you intended the default comparison against the default branch.
If you meant the three-dot form, choose a distinct base (e.g. --base master with target feature).

Example fix

// before
hub compare --base feature-x feature-x   // same as --base
// after
hub compare --base master feature-x

Defensive patterns

Strategy: validation

Validate before calling

// ensure base and target differ before invoking
if flagCompareBase != "" && flagCompareBase == targetBranch {
    return fmt.Errorf("--base must differ from the branch to compare")
}

Try / catch

if flagCompareBase == r {
    return fmt.Errorf("base (%s) equals compare target; pick a different base", r)
}

Prevention

In scripts, assert the two branch variables are not equal
Remember namespaced targets (owner:branch) compare as full strings
Review generated hub compare commands in CI logs

When it happens

Trigger: Running `hub compare --base X X` (or a branch that resolves to the same owner:branch string as --base, e.g. same branch name in the same project).

Common situations: Scripting the command with a variable holding the branch name that also got assigned to --base; passing the branch twice by habit; forgetting that bare names on the same repo resolve identically to the --base value.

Related errors

AI-assisted analysis of mislav/hub@5c547ed804 (2026-09-01). Data as JSON: /api/errors/f337e57bcb85c591. Report an issue: GitHub.