Get-Command with aliases: .Parameters collection does not include dynamic parameters

[mklement0]

Prerequisites

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• Refer to Differences between Windows PowerShell 5.1 and PowerShell.

Steps to reproduce

# To avoid an unrelated bug (#18715), make sure that Get-ChildItem was referenced at least once in this session.
$null = Get-ChildItem -? 

# Compare the parameter name reported via Get-ChildItem vs. via alias gci
# Be sure to call this from a *file-system* location.
Compare-Object @((Get-Command Get-ChildItem).Parameters.Keys) @((Get-Command gci).Parameters.Keys)

See also:

• Get-Command with aliases: if the command targeted by an alias has never been referenced in the session, the .Parameters collection is empty #18715

Expected behavior

No output (the same set of parameters should be reported by both Get-Command calls).

Actual behavior

InputObject   SideIndicator
-----------   -------------
Attributes    <=
FollowSymlink <=
Directory     <=
File          <=
Hidden        <=
ReadOnly      <=
System        <=

That is, all dynamic parameters are missing from what Get-Command gci).Parameters reported.

Error details

No response

Environment data

PowerShell Core 7.3.0

Visuals

No response

[kilasuit]

I get the following output in 2 different sessions (regardless of calling GCI or not) on a machine where I have previously used 7.3.0 & think these issues are due to the module command cache perhaps not having been built yet. This is also not from sessions run with no profile either

[mklement0]

Thanks, @kilasuit, the way I constructed my sample command serendipitously bypassed #18715, but if you reverse the Compare-Object operands you'll run into it:

# !! ERROR: "Cannot bind argument to parameter 'ReferenceObject' because it is null."
pwsh -nop { Compare-Object @((Get-Command gci).Parameters.Keys) @((Get-Command Get-ChildItem).Parameters.Keys) }

Adding a delay doesn't make a difference:

# !! DITTO
pwsh -nop { 1..10 | % { Start-Sleep 1}; Compare-Object @((Get-Command gci).Parameters.Keys) @((Get-Command Get-ChildItem).Parameters.Keys) }

Therefore, it doesn't appear to be a matter of timing: having referenced Get-ChildItem explicitly in a session is a prerequisite, and is enough to instantly make (Get-Command gci).Parameters return (the buggy) results.

[kilasuit]

I don't think you are right here as technically an alias has no parameters so you are getting the benefit of the engine knowing that you want to be lazy and use the alias in place of the full command name to give you access to it's parameters.

therefore the more that I think on this I think that this all works as it should

[mklement0]

An alias is just that: another name for an existing command, it stands to reason that it reports the latter's parameters, which it mostly does:

There is no justification either for the behavior reported here nor for the one in #18715. - both are unequivocally bugs.

[kilasuit]

Question really becomes

Should we expose parameters of aliased commands in this way so that (Get-Command gci).Parameters acts like (Get-Command Get-ChildItem).Parameters

To which I think yes we should but should also place reminders that aliases can be overridden (as can commands) and that if you want to be certain you should be using the fully qualified command name. I also don't think this goes far enough and would like to be able to version pin as well. As I raised in this issue ages ago

[microsoft-github-policy-service]

This issue has not had any activity in 6 months, if this is a bug please try to reproduce on the latest version of PowerShell and reopen a new issue and reference this issue if this is still a blocker for you.

[microsoft-github-policy-service]

This issue has not had any activity in 6 months, if this is a bug please try to reproduce on the latest version of PowerShell and reopen a new issue and reference this issue if this is still a blocker for you.

[microsoft-github-policy-service]

This issue has not had any activity in 6 months, if this is a bug please try to reproduce on the latest version of PowerShell and reopen a new issue and reference this issue if this is still a blocker for you.

[microsoft-github-policy-service]

This issue has been marked as "No Activity" as there has been no activity for 6 months. It has been closed for housekeeping purposes.