Use single value from pipeline parameter

[liamjpeters]

PR Summary

New rule to flag when multiple parameters in the same parameter set have ValueFromPipeline set to true.

When running something like:

function Test-ValueFromPipeline {
    [CmdletBinding()]
    param (
        [Parameter(ValueFromPipeline)]
        [string]
        $Parameter1,
        [Parameter(ValueFromPipeline)]
        [string]
        $Parameter2
    )
    process {
        "Parameter1: $Parameter1!"
        "Parameter2: $Parameter2!"
    }
}

"Value1" | Test-ValueFromPipeline

I don't get any kind of error or warning, which I was surprised by.

Consistent behaviour across both 5.1 and 7.4.11.

Multiple parameters accepting pipeline input by value doesn't make sense (to me at least - maybe I'm missing a use-case?).

The above outputs:

Parameter1: Value1!
Parameter2: Value1!

Both parameters get the pipeline input bound.

Parameter [Parameter2] PIPELINE INPUT ValueFromPipeline NO COERCION
BIND arg [Value1] to parameter [Parameter2]
    Executing DATA GENERATION metadata: [System.Management.Automation.ArgumentTypeConverterAttribute]
        result returned from DATA GENERATION: Value1
    BIND arg [Value1] to param [Parameter2] SUCCESSFUL
Parameter [Parameter1] PIPELINE INPUT ValueFromPipeline NO COERCION
BIND arg [Value1] to parameter [Parameter1]
    Executing DATA GENERATION metadata: [System.Management.Automation.ArgumentTypeConverterAttribute]
        result returned from DATA GENERATION: Value1
    BIND arg [Value1] to param [Parameter1] SUCCESSFUL

PR Checklist

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• Summarized changes
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