Powershell: ParentContainsErrorRecordException Invoking with shebang using -?

[TylerLeonhardt]

Steps to reproduce

First create a file with this in it (called foo.ps1):

#!/path/to/pwsh
[cmdletbinding()]
param($Foo, $Bar)
$Foo
$Bar

chmod the file so the shebang works: chmod +x foo.ps1

start bash and invoke the ps1 with the -? asking for help:

BASH > ./foo.ps1 -?

foo.ps1 [[-Foo] <Object>] [[-Bar] <Object>] [<CommonParameters>]

works fine... now rename the file to just foo: mv foo.ps1 foo

You'll notice invoking still works:

BASH >  foo 1234 "asdf"
1234
asdf

BUT Invoke the same command above:

BASH > ./foo -?

Expected behavior

foo.ps1 [[-Foo] <Object>] [[-Bar] <Object>] [<CommonParameters>]

Actual behavior

ParentContainsErrorRecordException: An error occurred while creating the pipeline.

Environment data

Name                           Value
----                           -----
PSVersion                      7.1.0-daily.20201028
PSEdition                      Core
GitCommitId                    7.1.0-daily.20201028
OS                             Darwin 19.6.0 Darwin Kernel Version 19.6.0: Mon Aug 31 22:12:52 PDT 2020; root:xnu-6153.141.2~1/RELEASE_X86_64
Platform                       Unix
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

[TylerLeonhardt]

Also interesting:

PS > Get-Help ./foo
Get-Help: Get-Help could not find ./foo in a help file in this session. To download updated help topics type: "Update-Help". To get help online, search for the help topic in the TechNet library at https://go.microsoft.com/fwlink/?LinkID=107116.
PS > mv foo foo.ps1
PS > Get-Help ./foo.ps1
foo.ps1 [[-Foo] <Object>] [[-Bar] <Object>] [<CommonParameters>]

cc @adityapatwardhan

[mklement0]

Possibly related to this longstanding bug: #4217

[iSazonov]

Dup?

[TylerLeonhardt]

maybe... but this issue is more scoped to help specifically.

[TylerLeonhardt]

I'm thinking this is because of how shebangs are handled... they're read into a string:
https://github.com/PowerShell/PowerShell/blob/af8558b065ac9e9c42d61efb6174bb485170618d/src/Microsoft.PowerShell.ConsoleHost/host/msh/ConsoleHost.cs#L1847-L1851

I'm wondering if help doesn't work on arbitrary script blocks.