feat: add lint rule for Bash nounset empty array expansions (#57)#62
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olavostauros wants to merge 3 commits into
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feat: add lint rule for Bash nounset empty array expansions (#57)#62olavostauros wants to merge 3 commits into
olavostauros wants to merge 3 commits into
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Adds bash-empty-array-expansions lint rule that flags ${array[@]}
and ${array[*]} under set -u (nounset), suggesting the Bash-3-safe
alternate-value form ${arr[@]+"${arr[@]}"}.
Shares nounset detection pattern with bash-empty-argv-forwarding (KnickKnackLabs#48):
- has_nounset() - detect set -u / set -eu / set -euo pipefail
- is_safe_context() - exclude for loops and local array assignments
- has_safe_form() - exclude already-safe alternate-value forms
Standard text-based ripgrep approach with 11 fixture scenarios and
15 BATS tests. ShellCheck-clean.
Implements KnickKnackLabs#57 (KnickKnackLabs/codebase)
This was referenced Jun 26, 2026
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Summary
Adds
bash-empty-array-expansionslint rule that flags"${array[@]}"and"${array[*]}"under nounset (set -u), suggesting the Bash-3-safe alternate-value form${arr[@]+"${arr[@]}"}. macOS Bash 3.2 treats these as unbound variables when the array is empty; Linux Bash 5+ and Homebrew Bash handle them gracefully, creating a silent cross-platform gotcha. ShellCheck does not catch this.Also collapses decorative 3-line section comment blocks (
# ============ Section ============) to single-line headers (# Section) across 9.batstest files, per KKL convention (AGENTS.md rule #4).Files changed
.mise/tasks/lint/bash-empty-array-expansionstest/lint/bash-empty-array-expansions/bash-empty-array-expansions.batstest/lint/bash-empty-array-expansions/fixtures/.mise/tasks/lint/shellcheckcodebase:ignore(guarded usage).mise/tasks/lint/github-actionscodebase:ignore(guarded usage).mise/tasks/lint/mise-settingscodebase:ignore(guarded usage)test/lint/bats-test-task/fixtures/clean/mise.tomltest/lib/shell-files.batstest/lint/bats-test-helper/bats-test-helper.batstest/lint/bats-test-task/bats-test-task.batstest/lint/gum-table/gum-table.batstest/lint/mcr-scope/mcr-scope.batstest/lint/mise-settings/mise-settings.batstest/lint/or-true/or-true.batstest/lint/shellcheck/shellcheck.batstest/migrations/task-pattern/task-pattern.batstest/pre-commit/pre-commit.batstest/scan/scan.batsValidation
mise run test— 233/233 pass (15 new tests at indices 7–21, zero regressions)mise run lint:bash-empty-array-expansions .— self-hosting clean (only test fixtures flagged)mise run lint:shellcheck .mise/tasks/lint/bash-empty-array-expansions— ShellCheck-cleangit diff --check— no whitespace errorsSister issue
This is the array sibling of #48 (bash-empty-argv-forwarding, PR #59). Both share nounset detection logic and the safe-context exclusion pattern.
Closes #57