fix(gem): Windows support for gem backend by my1e5 · Pull Request #8031 · jdx/mise

my1e5 · 2026-02-06T14:04:20Z

This PR provides fixes for Windows support for the gem backend.

Minimal example

$ mise --version
2026.2.5 windows-x64 (2026-02-06)

$ mise use ruby@3.4.8
ruby@3.4.8             3.6.9
mise C:\Users\my1e5\Projects\mise-project\mise.toml tools: ruby@3.4.8

$ mise use gem:ceedling@1.0.1
gem:ceedling@1.0.1     install                                                         ◜
mise ERROR Failed to install gem:ceedling@1.0.1: failed to execute command: gem install ceedling --version 1.0.1 --install-dir C:\Users\my1e5\AppData\Local\mise\installs\gem-ceedling\1.0.1\libexec: program not found
mise ERROR Run with --verbose or MISE_VERBOSE=1 for more information

See previous discussion:

Basic gem usage on Windows does not work #6338

Fixes

A fix for the Failed to install error is possible by using gem.cmd on Windows:

const GEM_PROGRAM: &str = if cfg!(windows) { "gem.cmd" } else { "gem" };

Using this patch enables the gem to be installed without error:

$ ./mise.exe --version
2026.2.5-DEBUG windows-x64 (2026-02-06)

$ ./mise.exe use gem:ceedling@1.0.1
gem:ceedling@1.0.1 
mise C:\Users\my1e5\Projects\mise-project\mise.toml tools: gem:ceedling@1.0.1

But then another error presented itself:

$ ./mise.exe x -- ceedling --version

C:\Users\my1e5\Projects\mise-project>#!/usr/bin/env bash 
'#!' is not recognized as an internal or external command,
operable program or batch file.

C:\Users\my1e5\Projects\mise-project>GEM_HOME="C:\Users\my1e5\AppData\Local\mise\installs\gem-ceedling\1.0.1\libexec" exec C:\Users\my1e5\AppData\Local\mise\installs\gem-ceedling\1.0.1\libexec/bin\ceedling.bat "$@"
'GEM_HOME' is not recognized as an internal or external command,
operable program or batch file.

A fix for this was to use Windows-compatible wrapper scripts. Create .cmd batch files instead of bash scripts on Windows:

@echo off
set "GEM_HOME=C:\path\to\libexec"
"C:\path\to\libexec\bin\ceedling.bat" %*

Now it is working normally:

$ ./mise.exe x -- ceedling --version
Welcome to Ceedling!

  Ceedling => 1.0.1-fb1ce6c
  ----------------------
  C:/Users/my1e5/AppData/Local/mise/installs/gem-ceedling/1.0.1/libexec/gems/ceedling-1.0.1/

  Build Frameworks
  ----------------------
       CMock => 2.6.0
       Unity => 2.6.1
  CException => 1.3.4

AI Disclosure

This PR was co-authored by Copilot, but I have reviewed the changes and tested them myself on my own Windows PC.

Co-authored-by: my1e5 <10064103+my1e5@users.noreply.github.com>

gemini-code-assist · 2026-02-06T14:04:37Z

Summary of Changes

Hello @my1e5, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances the mise tool's gem backend by introducing robust Windows compatibility. It addresses critical issues that prevented Ruby gems from being installed and executed correctly on Windows, thereby expanding the utility of mise for Ruby developers working in a Windows environment.

Highlights

Windows Compatibility for Gem Backend: Implemented support for the gem backend on Windows, resolving issues with gem installation and execution.
Conditional gem Command Usage: The gem command is now conditionally set to gem.cmd on Windows to ensure proper execution of RubyGems commands.
Windows-Specific Wrapper Scripts: Introduced the creation of .cmd batch files as wrapper scripts for gem executables on Windows, replacing bash scripts to correctly handle environment variables and command execution.
Platform-Specific Code Paths: Refactored the code to use #[cfg(windows)] and #[cfg(unix)] attributes, ensuring that shebang rewriting and Ruby symlink creation logic are only applied on Unix-like systems, while Windows-specific wrapper script generation is handled separately.

Changelog

src/backend/gem.rs
- Added GEM_PROGRAM constant to dynamically select 'gem' or 'gem.cmd' based on the operating system.
- Updated CmdLineRunner calls to use the new GEM_PROGRAM constant for gem commands.
- Encapsulated Unix-specific shebang rewriting and Ruby symlink creation logic within #[cfg(unix)] blocks.
- Implemented a #[cfg(windows)] version of env_script_all_bin_files to generate .cmd wrapper scripts for gem executables, correctly setting GEM_HOME and executing the gem.
- Improved error handling for path conversions (UTF-8) in env_script_all_bin_files.
- Applied #[cfg(unix)] to create_ruby_symlink, rewrite_gem_shebangs, find_ruby_shebang, is_mise_ruby_path, and to_minor_version_shebang functions.
- Applied #[cfg(any(unix, test))] to extract_minor_version.

Activity

The author, my1e5, identified and provided solutions for two distinct issues preventing gem backend functionality on Windows.
The initial problem involved gem install failing due to the gem command not being found, which was resolved by using gem.cmd.
A subsequent issue with executing installed gems, caused by bash-specific scripts, was fixed by generating Windows-compatible .cmd wrapper files.
The author confirmed that the changes were co-authored by Copilot but personally reviewed and tested on a Windows PC.
This PR follows up on previous discussions regarding Windows support for mise's gem backend, specifically referencing GitHub discussion Basic gem usage on Windows does not work #6338.

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gemini-code-assist

Code Review

This pull request effectively adds Windows support for the gem backend by introducing platform-specific logic for executable names and wrapper script generation. The changes are well-implemented, using conditional compilation to separate Unix and Windows code paths. Additionally, error handling has been improved by replacing panicking .unwrap() calls with proper error propagation. I have one suggestion to refactor some duplicated code between the platform-specific functions to improve maintainability.

gemini-code-assist · 2026-02-06T14:06:44Z

src/backend/gem.rs

+#[cfg(unix)]
 fn env_script_all_bin_files(install_path: &Path) -> eyre::Result<bool> {
    let install_bin_path = install_path.join("bin");
    let install_libexec_path = install_path.join("libexec");

    file::create_dir_all(&install_bin_path)?;

-    get_gem_executables(install_path)?
-        .into_iter()
-        .for_each(|path| {
-            let exec_path = install_bin_path.join(path.file_name().unwrap());
-            file::write(
-                &exec_path,
-                formatdoc!(
-                    r#"
-                    #!/usr/bin/env bash
-                    GEM_HOME="{gem_home}" exec {gem_exec_path} "$@"
-                    "#,
-                    gem_home = install_libexec_path.to_str().unwrap(),
-                    gem_exec_path = path.to_str().unwrap(),
-                ),
+    for path in get_gem_executables(install_path)? {
+        let file_name = path
+            .file_name()
+            .ok_or_else(|| eyre::eyre!("invalid gem executable path: {}", path.display()))?;
+        let exec_path = install_bin_path.join(file_name);
+        let gem_exec_path = path.to_str().ok_or_else(|| {
+            eyre::eyre!(
+                "gem executable path contains invalid UTF-8: {}",
+                path.display()
+            )
+        })?;
+        let gem_home = install_libexec_path.to_str().ok_or_else(|| {
+            eyre::eyre!(
+                "libexec path contains invalid UTF-8: {}",
+                install_libexec_path.display()
            )
-            .unwrap();
-            file::make_executable(&exec_path).unwrap();
-        });
+        })?;
+        file::write(
+            &exec_path,
+            formatdoc!(
+                r#"
+                #!/usr/bin/env bash
+                GEM_HOME="{gem_home}" exec {gem_exec_path} "$@"
+                "#,
+                gem_home = gem_home,
+                gem_exec_path = gem_exec_path,
+            ),
+        )?;
+        file::make_executable(&exec_path)?;
+    }
+
+    Ok(true)
+}
+
+#[cfg(windows)]
+fn env_script_all_bin_files(install_path: &Path) -> eyre::Result<bool> {
+    let install_bin_path = install_path.join("bin");
+    let install_libexec_path = install_path.join("libexec");
+
+    file::create_dir_all(&install_bin_path)?;
+
+    for path in get_gem_executables(install_path)? {
+        // On Windows, create .cmd wrapper scripts
+        let file_stem = path
+            .file_stem()
+            .ok_or_else(|| eyre::eyre!("invalid gem executable path: {}", path.display()))?
+            .to_string_lossy();
+        let exec_path = install_bin_path.join(format!("{}.cmd", file_stem));
+        let gem_exec_path = path.to_str().ok_or_else(|| {
+            eyre::eyre!(
+                "gem executable path contains invalid UTF-8: {}",
+                path.display()
+            )
+        })?;
+        let gem_home = install_libexec_path.to_str().ok_or_else(|| {
+            eyre::eyre!(
+                "libexec path contains invalid UTF-8: {}",
+                install_libexec_path.display()
+            )
+        })?;
+        file::write(
+            &exec_path,
+            formatdoc!(
+                r#"@echo off
+                set "GEM_HOME={gem_home}"
+                "{gem_exec_path}" %*
+                "#,
+                gem_home = gem_home,
+                gem_exec_path = gem_exec_path,
+            ),
+        )?;
+    }

    Ok(true)
 }


These two platform-specific env_script_all_bin_files functions share some duplicated logic (e.g., path setup, looping, and error handling). To improve maintainability, consider refactoring this into a single function that calls a platform-specific helper for creating the wrapper script. This would centralize the common logic and reduce redundancy.

Copilot

Pull request overview

This PR adds Windows support for the gem backend by addressing two main issues: using gem.cmd instead of gem on Windows, and creating Windows-compatible wrapper scripts for installed gem executables. The changes follow similar patterns already established in the codebase for the npm backend.

Changes:

Introduces a platform-specific GEM_PROGRAM constant that resolves to gem.cmd on Windows and gem on Unix
Adds a Windows-specific implementation of env_script_all_bin_files that creates .cmd batch wrapper scripts instead of bash scripts
Wraps Unix-specific gem setup functions (shebang rewriting, Ruby symlink creation) with #[cfg(unix)] attributes to prevent compilation on Windows

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src/backend/gem.rs

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

jdx · 2026-02-06T14:54:03Z

src/backend/gem.rs

+        file::write(
+            &exec_path,
+            formatdoc!(
+                r#"\n


typo? or intentional?

This change was suggested by the Copilot PR review - #8031 (comment)

fair enough

Sorry, I should have checked that suggestion (#8031 (comment)) by Copilot more carefully. The newline it suggested should be added causes `'\n' is not recognized as an internal or external command, operable program or batch file.`: ``` $ ./mise.exe x -- ceedling --version C:\Users\my1e5\Projects\mise-project>\n '\n' is not recognized as an internal or external command, operable program or batch file. Welcome to Ceedling! Ceedling => 1.0.1-fb1ce6c ---------------------- C:/Users/my1e5/AppData/Local/mise/installs/gem-ceedling/1.0.1/libexec/gems/ceedling-1.0.1/ Build Frameworks ---------------------- CMock => 2.6.0 Unity => 2.6.1 CException => 1.3.4 ``` This PR reverts that change.

@jdx

### 🚀 Features - **(env)** add shell-style variable expansion in env values by @jdx in [#8029](#8029) - **(list)** add --all-sources flag to list command by @TylerHillery in [#8019](#8019) ### 🐛 Bug Fixes - **(gem)** Windows support for gem backend by @my1e5 in [#8031](#8031) - **(gem)** revert gem.rs script newline change by @my1e5 in [#8034](#8034) - **(lock)** write tools to lockfile matching their source config by @jdx in [#8012](#8012) - **(ls)** sort sources deterministically in --all-sources output by @jdx in [#8037](#8037) - **(task)** auto-install tools from mise.toml for file tasks by @jdx in [#8030](#8030) ### 📚 Documentation - fix wrong positions of `mise run` flags by @muzimuzhi in [#8036](#8036) ### 📦️ Dependency Updates - update ghcr.io/jdx/mise:copr docker digest to 3e00d7d by @renovate[bot] in [#8023](#8023) - update ghcr.io/jdx/mise:alpine docker digest to 0ced1b3 by @renovate[bot] in [#8022](#8022) ### 📦 Registry - add tirith ([github:sheeki03/tirith](https://github.com/sheeki03/tirith)) by @sheeki03 in [#8024](#8024) - add mas by @TyceHerrman in [#8032](#8032) ### Security - **(deps)** update time crate to 0.3.47 to fix RUSTSEC-2026-0009 by @jdx in [#8026](#8026) ### New Contributors - @sheeki03 made their first contribution in [#8024](#8024) - @TylerHillery made their first contribution in [#8019](#8019) ## 📦 Aqua Registry Updates #### New Packages (1) - [`kubernetes-sigs/kubectl-validate`](https://github.com/kubernetes-sigs/kubectl-validate) #### Updated Packages (6) - [`flux-iac/tofu-controller/tfctl`](https://github.com/flux-iac/tofu-controller/tfctl) - [`gogs/gogs`](https://github.com/gogs/gogs) - [`j178/prek`](https://github.com/j178/prek) - [`syncthing/syncthing`](https://github.com/syncthing/syncthing) - [`tuist/tuist`](https://github.com/tuist/tuist) - [`yaml/yamlscript`](https://github.com/yaml/yamlscript)

@echo

This PR provides fixes for Windows support for the gem backend. ## Minimal example ``` $ mise --version 2026.2.5 windows-x64 (2026-02-06) $ mise use ruby@3.4.8 ruby@3.4.8 3.6.9 mise C:\Users\my1e5\Projects\mise-project\mise.toml tools: ruby@3.4.8 $ mise use gem:ceedling@1.0.1 gem:ceedling@1.0.1 install ◜ mise ERROR Failed to install gem:ceedling@1.0.1: failed to execute command: gem install ceedling --version 1.0.1 --install-dir C:\Users\my1e5\AppData\Local\mise\installs\gem-ceedling\1.0.1\libexec: program not found mise ERROR Run with --verbose or MISE_VERBOSE=1 for more information ``` See previous discussion: - jdx#6338 ## Fixes A fix for the `Failed to install` error is possible by using `gem.cmd` on Windows: ``` const GEM_PROGRAM: &str = if cfg!(windows) { "gem.cmd" } else { "gem" }; ``` Using this patch enables the gem to be installed without error: ``` $ ./mise.exe --version 2026.2.5-DEBUG windows-x64 (2026-02-06) $ ./mise.exe use gem:ceedling@1.0.1 gem:ceedling@1.0.1 mise C:\Users\my1e5\Projects\mise-project\mise.toml tools: gem:ceedling@1.0.1 ``` But then another error presented itself: ``` $ ./mise.exe x -- ceedling --version C:\Users\my1e5\Projects\mise-project>#!/usr/bin/env bash '#!' is not recognized as an internal or external command, operable program or batch file. C:\Users\my1e5\Projects\mise-project>GEM_HOME="C:\Users\my1e5\AppData\Local\mise\installs\gem-ceedling\1.0.1\libexec" exec C:\Users\my1e5\AppData\Local\mise\installs\gem-ceedling\1.0.1\libexec/bin\ceedling.bat "$@" 'GEM_HOME' is not recognized as an internal or external command, operable program or batch file. ``` A fix for this was to use Windows-compatible wrapper scripts. Create .cmd batch files instead of bash scripts on Windows: ``` @echo off set "GEM_HOME=C:\path\to\libexec" "C:\path\to\libexec\bin\ceedling.bat" %* ``` Now it is working normally: ``` $ ./mise.exe x -- ceedling --version Welcome to Ceedling! Ceedling => 1.0.1-fb1ce6c ---------------------- C:/Users/my1e5/AppData/Local/mise/installs/gem-ceedling/1.0.1/libexec/gems/ceedling-1.0.1/ Build Frameworks ---------------------- CMock => 2.6.0 Unity => 2.6.1 CException => 1.3.4 ``` ### AI Disclosure This PR was co-authored by Copilot, but I have reviewed the changes and tested them myself on my own Windows PC. --------- Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Sorry, I should have checked that suggestion (jdx#8031 (comment)) by Copilot more carefully. The newline it suggested should be added causes `'\n' is not recognized as an internal or external command, operable program or batch file.`: ``` $ ./mise.exe x -- ceedling --version C:\Users\my1e5\Projects\mise-project>\n '\n' is not recognized as an internal or external command, operable program or batch file. Welcome to Ceedling! Ceedling => 1.0.1-fb1ce6c ---------------------- C:/Users/my1e5/AppData/Local/mise/installs/gem-ceedling/1.0.1/libexec/gems/ceedling-1.0.1/ Build Frameworks ---------------------- CMock => 2.6.0 Unity => 2.6.1 CException => 1.3.4 ``` This PR reverts that change.

@jdx

### 🚀 Features - **(env)** add shell-style variable expansion in env values by @jdx in [jdx#8029](jdx#8029) - **(list)** add --all-sources flag to list command by @TylerHillery in [jdx#8019](jdx#8019) ### 🐛 Bug Fixes - **(gem)** Windows support for gem backend by @my1e5 in [jdx#8031](jdx#8031) - **(gem)** revert gem.rs script newline change by @my1e5 in [jdx#8034](jdx#8034) - **(lock)** write tools to lockfile matching their source config by @jdx in [jdx#8012](jdx#8012) - **(ls)** sort sources deterministically in --all-sources output by @jdx in [jdx#8037](jdx#8037) - **(task)** auto-install tools from mise.toml for file tasks by @jdx in [jdx#8030](jdx#8030) ### 📚 Documentation - fix wrong positions of `mise run` flags by @muzimuzhi in [jdx#8036](jdx#8036) ### 📦️ Dependency Updates - update ghcr.io/jdx/mise:copr docker digest to 3e00d7d by @renovate[bot] in [jdx#8023](jdx#8023) - update ghcr.io/jdx/mise:alpine docker digest to 0ced1b3 by @renovate[bot] in [jdx#8022](jdx#8022) ### 📦 Registry - add tirith ([github:sheeki03/tirith](https://github.com/sheeki03/tirith)) by @sheeki03 in [jdx#8024](jdx#8024) - add mas by @TyceHerrman in [jdx#8032](jdx#8032) ### Security - **(deps)** update time crate to 0.3.47 to fix RUSTSEC-2026-0009 by @jdx in [jdx#8026](jdx#8026) ### New Contributors - @sheeki03 made their first contribution in [jdx#8024](jdx#8024) - @TylerHillery made their first contribution in [jdx#8019](jdx#8019) ## 📦 Aqua Registry Updates #### New Packages (1) - [`kubernetes-sigs/kubectl-validate`](https://github.com/kubernetes-sigs/kubectl-validate) #### Updated Packages (6) - [`flux-iac/tofu-controller/tfctl`](https://github.com/flux-iac/tofu-controller/tfctl) - [`gogs/gogs`](https://github.com/gogs/gogs) - [`j178/prek`](https://github.com/j178/prek) - [`syncthing/syncthing`](https://github.com/syncthing/syncthing) - [`tuist/tuist`](https://github.com/tuist/tuist) - [`yaml/yamlscript`](https://github.com/yaml/yamlscript)

Copilot AI and others added 4 commits February 6, 2026 10:58

Initial plan

936f166

fix(gem): use gem.cmd on Windows

fa4dd9d

Co-authored-by: my1e5 <10064103+my1e5@users.noreply.github.com>

fix(gem): create Windows-compatible .cmd wrapper scripts

5fea7f8

Co-authored-by: my1e5 <10064103+my1e5@users.noreply.github.com>

fix(gem): improve error handling in wrapper script generation

65b77ce

Co-authored-by: my1e5 <10064103+my1e5@users.noreply.github.com>

Copilot AI review requested due to automatic review settings February 6, 2026 14:04

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my1e5 and others added 2 commits February 6, 2026 14:12

Update src/backend/gem.rs

79fcc85

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Merge branch 'main' into copilot/fix-gem-installation-error

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jdx merged commit a054199 into jdx:main Feb 6, 2026
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mise-en-dev mentioned this pull request Feb 6, 2026

chore: release 2026.2.6 #8027

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fix(gem): revert gem.rs script newline change #8034

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mise 2026.2.6 Homebrew/homebrew-core#266311

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fix(gem): Windows support for gem backend#8031

fix(gem): Windows support for gem backend#8031
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my1e5 commented Feb 6, 2026

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