PowerShell alias calling non-existent command returns 0 exit code

[brycegbrazen]

Running an alias using the Powershell shell plugin with rez-env doesn't return a failure exit code when attempting to run a non-existent aliased command in-line.

Environment

• Windows 10
• Rez 2.112.0
• Rez python version 3.7.9

To Reproduce

1. Create a package.py for a test_invalid_alias package with the following definition:

   
   name = "test_invalid_alias"

version = "1.0.0"

build_command = ""

def commands(): alias('my_alias', 'a_non_existent_executable')

2. Install the package to your package repository.
3. Run `rez-env -- a_non_existent_executable`
4. Observe the following error message:

& : The term 'a_non_existent_executable' is not recognized as the name of a cmdlet, function, script file, or operable program. Check the spelling of the name, or if a path was included, verify that the path is correct and try again. At C:\Users\bryce.gattis\AppData\Local\Temp\rez_context_2bfjto0k\rez-shell.ps1:4 char:3

• & a_non_existent_executable

• 
  + CategoryInfo          : ObjectNotFound: (a_non_existent_executable:String) [], CommandNotFoundException
  + FullyQualifiedErrorId : CommandNotFoundException
  ```
  5. Run `rez-env test_invalid_alias -- my_alias`
  6. Observe $LASTEXITCODE as being 0 instead of a non-zero exit code.

Use Case This is currently happening and causing issues on our render farm. With Rez, we are creating aliases for python that map to whatever the DCC's version of python is. For example, the python alias for Houdini maps to hython.

The behavior observed via this issue is problematic when a specific machine doesn't have the correct version of Houdini installed on their machine. Rez will still use the alias (and expect that the corresponding software is installed where the Rez package is looking for it), but will not correctly return a non-zero exit code if the executable is not found.

This causes false positives on our render farm.

Related Issues/PRs

• Added failing test in #1801

Expected behavior A non-zero exit code is returned.

Actual behavior A 0 exit code is returned.

[dbr]

I had similar problem exposing commands like nuke as an alias for Nuke15.0 etc

The aliases don't seem to propagate any error codes (so even if the command starts, but say it fails mid-render - then farm monitoring software doesn't notice the job failed)

I ended up replacing all aliases with .bat scripts, e.g our nuke.bat contains:

@echo off
"%~dp0\nuke\Nuke15.0.exe" %*

and so on, and these get added to $PATH instead of using Rez's alias(...)

Wrapper scripts like this are slightly less convenient to setup, but they seem a lot more robust - e.g even in bash, aliases have some weird properties which makes them a flaky solution for this problem (mainly they don't get inherited into child shells - so if you did rez env mypackagewithanalias -- my_alias would work but rez env mypackagewithanalias -- bash -c 'myalias' would fail)