fix(activate): handle empty __MISE_FLAGS array with set -u on bash 3.2 by jdx · Pull Request #8988 · jdx/mise

jdx · 2026-04-10T01:59:13Z

Summary

Use ${arr[@]+"${arr[@]}"} pattern to safely expand the __MISE_FLAGS array when empty
Bash < 4.4 (including macOS's default bash 3.2) treats "${arr[@]}" on an empty array as an unbound variable under set -u (nounset)
This causes scripts that source .bashrc (which contains eval "$(mise activate bash)") to fail with: __MISE_FLAGS[@]: unbound variable

Test plan

Verified the bug reproduces on bash 3.2 (via docker run bash:3.2) with set -u and empty __MISE_FLAGS=()
Verified the fix works on bash 3.2 with set -u and empty flags
Verified non-empty flags still pass through correctly (--status)
Snapshot tests updated and passing

🤖 Generated with Claude Code

Note

Low Risk
Low risk: small change to Bash activation script argument expansion, mainly affecting older Bash with set -u; behavior should be unchanged when flags are present.

Overview
Fixes Bash activation hooks to safely expand __MISE_FLAGS even when the array is empty under set -u (notably on Bash 3.2), by switching to the ${arr[@]+"${arr[@]}"} expansion pattern.

Updates the corresponding snapshot (mise__shell__bash__tests__activate.snap) to match the new generated activation script output.

^{Reviewed by Cursor Bugbot for commit 15c7af0. Bugbot is set up for automated code reviews on this repo. Configure here.}

Use ${arr[@]+"${arr[@]}"} pattern to safely expand the __MISE_FLAGS array when it is empty. Bash < 4.4 (including macOS's default bash 3.2) treats "${arr[@]}" on an empty array as an unbound variable under set -u (nounset), causing scripts that source .bashrc to fail with: __MISE_FLAGS[@]: unbound variable Fixes #8987 Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

greptile-apps · 2026-04-10T02:00:41Z

Greptile Summary

Fixes a bash 3.2 / set -u compatibility bug where "${__MISE_FLAGS[@]}" on an empty array was treated as an unbound variable under nounset, crashing scripts that source .bashrc after eval "$(mise activate bash)". The fix replaces all three occurrences with the standard ${__MISE_FLAGS[@]+"${__MISE_FLAGS[@]}"} safe-expansion idiom, and the snapshot is updated to match.

Confidence Score: 5/5

Safe to merge — minimal, well-understood shell quoting fix with no regressions.

The ${arr[@]+"${arr[@]}"} idiom is the canonical solution for this exact bash 3.2 nounset/empty-array issue, applied consistently at all three call sites. The non-empty path is covered by the snapshot test (which passes), and the empty-array path was manually verified on bash 3.2 per the PR description. No logic changes outside the expansion syntax.

No files require special attention.

Important Files Changed

Filename	Overview
src/assets/bash/activate.sh	Replaces `"${__MISE_FLAGS[@]}"` with the safe `${arr[@]+"${arr[@]}"}` idiom in all three `hook-env` call sites, correctly fixing the bash 3.2 nounset crash.
src/shell/snapshots/mise__shell__bash__tests__activate.snap	Snapshot updated to reflect the new safe array expansion syntax; consistent with the source change.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A["Hook function called"] --> B{"__MISE_FLAGS empty?"}
    B -- "Yes" --> C["Safe expansion produces nothing\nNo nounset error on bash 3.2"]
    B -- "No" --> D["Flags expanded correctly\ne.g. --status"]
    C --> E["mise hook-env -s bash"]
    D --> E
    E --> F["eval output"]

_{Reviews (2): Last reviewed commit: "fix(activate): handle empty __MISE_FLAGS..." | Re-trigger Greptile}

gemini-code-assist

Code Review

This pull request updates the Bash activation script and its snapshots to use a conditional array expansion for __MISE_FLAGS, which avoids 'unbound variable' errors when set -u is active. The review feedback correctly identifies that the new expansion is unquoted, which will cause word splitting issues if any array elements contain spaces.

gemini-code-assist · 2026-04-10T02:02:35Z

 _mise_hook() {
 	local previous_exit_status=$?
-	eval "$(mise hook-env "${__MISE_FLAGS[@]}" -s bash)"
+	eval "$(mise hook-env ${__MISE_FLAGS[@]+"${__MISE_FLAGS[@]}"} -s bash)"


The expansion ${__MISE_FLAGS[@]+"${__MISE_FLAGS[@]}"} is unquoted, which makes it subject to word splitting by the shell (using IFS). If any element in __MISE_FLAGS contains spaces (for example, a path provided via a flag), it will be incorrectly split into multiple arguments before being passed to the mise function. While this pattern is a standard workaround for the set -u issue in Bash versions prior to 4.4, it is only fully safe if the array elements are guaranteed not to contain IFS characters or if IFS is temporarily cleared.

gemini-code-assist · 2026-04-10T02:02:35Z

 			return $previous_exit_status
 		fi
-		eval "$(mise hook-env "${__MISE_FLAGS[@]}" -s bash --reason precmd)"
+		eval "$(mise hook-env ${__MISE_FLAGS[@]+"${__MISE_FLAGS[@]}"} -s bash --reason precmd)"


This expansion is unquoted and subject to word splitting, which may cause issues if __MISE_FLAGS contains elements with spaces.

gemini-code-assist · 2026-04-10T02:02:35Z

 		local previous_exit_status=$?
 		__MISE_BASH_CHPWD_RAN=1
-		eval "$(mise hook-env "${__MISE_FLAGS[@]}" -s bash --reason chpwd)"
+		eval "$(mise hook-env ${__MISE_FLAGS[@]+"${__MISE_FLAGS[@]}"} -s bash --reason chpwd)"


This expansion is unquoted and subject to word splitting, which may cause issues if __MISE_FLAGS contains elements with spaces.

github-actions · 2026-04-10T02:19:31Z

Hyperfine Performance

`mise x -- echo`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`mise-2026.4.7 x -- echo`	21.7 ± 0.4	21.2	25.1	1.00
`mise x -- echo`	22.2 ± 0.4	21.5	26.0	1.02 ± 0.03

`mise env`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`mise-2026.4.7 env`	21.4 ± 0.7	20.6	27.2	1.00
`mise env`	21.7 ± 0.3	21.0	23.1	1.02 ± 0.04

`mise hook-env`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`mise-2026.4.7 hook-env`	21.9 ± 0.4	21.2	23.6	1.00
`mise hook-env`	22.3 ± 0.4	21.6	26.3	1.02 ± 0.03

`mise ls`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`mise-2026.4.7 ls`	19.3 ± 0.4	18.7	24.0	1.00
`mise ls`	19.8 ± 0.5	19.1	21.6	1.02 ± 0.03

`xtasks/test/perf`

Command	mise-2026.4.7	mise	Variance
install (cached)	146ms	147ms	+0%
ls (cached)	76ms	76ms	+0%
bin-paths (cached)	80ms	81ms	-1%
task-ls (cached)	821ms	803ms	+2%

@cameronbrill

### 🚀 Features - **(config)** add lockfile_platforms setting to restrict lockfile platforms by @cameronbrill in [#8966](#8966) - **(sandbox)** support wildcard patterns in allow_env by @jdx in [#8974](#8974) - bump usage-lib v2 → v3 to render examples in task --help by @baby-joel in [#8890](#8890) ### 🐛 Bug Fixes - **(activate)** handle empty __MISE_FLAGS array with set -u on bash 3.2 by @jdx in [#8988](#8988) - **(env)** add trace logging for module hook PATH diagnostics by @jdx in [#8981](#8981) - **(go)** Query module proxy directly for version resolution by @c22 in [#8968](#8968) - **(install)** render tera templates in tool postinstall hooks by @jdx in [#8978](#8978) - **(install)** add missing env vars to tool postinstall hooks by @jdx in [#8977](#8977) - **(task)** prevent hang when skipped task has dependents by @jdx in [#8937](#8937) - **(task)** invalidate dependent task sources when dependency runs by @jdx in [#8975](#8975) - **(task)** prevent deadlock when MISE_JOBS=1 with sub-task references by @jdx in [#8976](#8976) - **(task)** fetch remote task files before parsing usage specs by @jdx in [#8979](#8979) - **(task)** prevent panic when running parallel sub-tasks with replacing output by @jdx in [#8986](#8986) - **(upgrade)** update lockfile and config when upgrading to specific version by @jdx in [#8983](#8983) ### 📚 Documentation - **(node)** remove "recommended for teams" from pin example by @jdx in [b334363](b334363) ### 📦️ Dependency Updates - update ghcr.io/jdx/mise:alpine docker digest to 17a29f2 by @renovate[bot] in [#8995](#8995) - update docker/dockerfile:1 docker digest to 2780b5c by @renovate[bot] in [#8994](#8994) ### New Contributors - @baby-joel made their first contribution in [#8890](#8890) - @cameronbrill made their first contribution in [#8966](#8966) - @c22 made their first contribution in [#8968](#8968)

jdx force-pushed the fix/bash-activate-nounset branch from b4c7f99 to 15c7af0 Compare April 10, 2026 02:00

gemini-code-assist Bot reviewed Apr 10, 2026

View reviewed changes

jdx enabled auto-merge (squash) April 10, 2026 02:05

jdx merged commit e3d374e into main Apr 10, 2026
36 checks passed

jdx deleted the fix/bash-activate-nounset branch April 10, 2026 02:15

mise-en-dev mentioned this pull request Apr 10, 2026

chore: release 2026.4.8 #8972

Merged

BrewTestBot mentioned this pull request Apr 10, 2026

mise 2026.4.8 Homebrew/homebrew-core#276976

Merged

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

fix(activate): handle empty __MISE_FLAGS array with set -u on bash 3.2#8988

fix(activate): handle empty __MISE_FLAGS array with set -u on bash 3.2#8988
jdx merged 1 commit intomainfrom
fix/bash-activate-nounset

jdx commented Apr 10, 2026 •

edited by cursor Bot

Loading

Uh oh!

greptile-apps Bot commented Apr 10, 2026 •

edited

Loading

Uh oh!

gemini-code-assist Bot left a comment

Uh oh!

gemini-code-assist Bot Apr 10, 2026

Uh oh!

gemini-code-assist Bot Apr 10, 2026

Uh oh!

gemini-code-assist Bot Apr 10, 2026

Uh oh!

Uh oh!

github-actions Bot commented Apr 10, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

1 participant

Uh oh!

Conversation

jdx commented Apr 10, 2026 • edited by cursor Bot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Summary

Test plan

Uh oh!

greptile-apps Bot commented Apr 10, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Greptile Summary

Confidence Score: 5/5

Important Files Changed

Flowchart

Uh oh!

gemini-code-assist Bot left a comment

Choose a reason for hiding this comment

Code Review

Uh oh!

gemini-code-assist Bot Apr 10, 2026

Choose a reason for hiding this comment

Uh oh!

gemini-code-assist Bot Apr 10, 2026

Choose a reason for hiding this comment

Uh oh!

gemini-code-assist Bot Apr 10, 2026

Choose a reason for hiding this comment

Uh oh!

Uh oh!

github-actions Bot commented Apr 10, 2026

Hyperfine Performance

mise x -- echo

mise env

mise hook-env

mise ls

xtasks/test/perf

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

1 participant

jdx commented Apr 10, 2026 •

edited by cursor Bot

Loading

greptile-apps Bot commented Apr 10, 2026 •

edited

Loading

`mise x -- echo`

`mise env`

`mise hook-env`

`mise ls`

`xtasks/test/perf`