Setting property values with the .ForEach() array method doesn't work with a single [pscustomobject] instance.

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Steps to reproduce

.ForEach() has an overload that allows setting property values by name and (array of) property values.

This works in general, but unexpectedly not with a single [pscustomobject] instance (as later discovered, it does work with arrays of [pscustomobject] instances).

($obj = [pscustomobject] @{ p = 1 }).ForEach('p', 42)

Expected behavior

No output, and $obj.p should report 42 afterwards.

Actual behavior

1 - the current property value - is output, and the attempt to assign a new value is ignored.

Error details

No response

Environment data

PowerShell Core 7.3.0-preview.1

Visuals

No response

[SeeminglyScience]

Aside from the second one (which appears to be a very bizarre but separate binding bug) that all looks right. Where and ForEach always return a Collection<> regardless of the input.

[SeeminglyScience]

Looks like the binder is calling InvokeAdaptedMember instead of EnumerableOps.ForEach.

Here’s the Bind result for a scalar int:

if (((target is int) && (_version == 0)) && ((member is string) && (value is string)))
{
    return EnumerableOps.ForEach(
        Fake.Dynamic<Func<CallSite, IEnumerator, IEnumerator>>(PSEnumerableBinder.Get())(
            Fake.Dynamic<Func<CallSite, object[], IEnumerator>>(PSEnumerableBinder.Get())(
                new object[] { target })),
        member,
        new object[] { value });
}

(side note, dunno what’s up with the double enumerate there)

And here it is for a pscustomobject:

if ((((_version == 0) && (target is PSObject)) && ((PSObject.Base(target) == target) && (member is string))) &&
    (value is string))
{
    return PSInvokeMemberBinder.InvokeAdaptedMember(PSObject.Base(target), "ForEach", new object[] { member, value });
}