Powershell: `?.` operator treats `DBNull` as null causing the methods to not execute

Created on 15 Nov 2019 · 4Comments · Source: PowerShell/PowerShell

Since the implementation of ?. operator treats DBNull, NullString and AutomationNull as null, we cannot call any method on them using ?. operator. The concern is only for DBNull as for other types we truly consider them as null.

Steps to reproduce

[System.DBNull]::Value?.GetTypeCode()

Expected behavior

DBNull

Actual behavior

null

Environment data

Build after PR https://github.com/PowerShell/PowerShell/pull/10960 is merged

Issue-Question

Source

adityapatwardhan

Most helpful comment

I feel we've already crossed this bridge once we decided awhile back that [System.DBNull]::Value -eq $null so usage expects it to act like it was $null (current design) otherwise it'll confuse users with the inconsistency. They can always workaround this by not using this operator.

SteveL-MSFT on 16 Nov 2019

👍5

All 4 comments

This will also affect NullString.Value -- if you are referencing LanguagePrimitives.IsNullLike() anywhere in the implementation of ?. or ?[] you probably want to switch to LanguagePrimitives.IsNull()

vexx32 on 15 Nov 2019

Yes I think we either agree that ?. uses IsNullLike(), in which case I think this is by design, or we use IsNull(), in which case there's a change to make.