Show what experimental features are turned on at the start of interactive sessions

Summary of the new feature/enhancement

For an interactive PowerShell user it is important to know if and what experimental features are currently enabled - if any.

• In a stable / LTS version, the expectation may be that NONE are enabled, so if any are, it’s helpful to be notified.

  • Experimental features may inadvertently be enabled, namely if, in a previously installed or side-by-side preview version features were ever selectively enabled or disabled with -Scope CurrentUser - which is the default scope. The resulting "$(Split-Path $PROFILE.CurrentUserAllHosts)/powershell.config.json" file takes effect for all installed versions, and overrides "PSHOME/powershell.config.json"

• In preview versions - which by default come with all experimental features enabled - it is additionally important to know which ones are not enabled in a given session, since, after using selective disabling, newly introduced features may end up DISABLED in preview versions installed later (as explained above).

  • Additionally, showing in effect all experimental features helps with discovering new ones.

Proposed technical implementation details (optional)

Update: See the alternative, less verbose proposal below.

On entering an interactive session, show something like the following:

For PREVIEW versions:

Show both the enabled and disabled experimental features, grouped by state:

@"
PowerShell 7.2.0-preview.3
Copyright (c) Microsoft Corporation.

https://aka.ms/powershell
Type 'help' to get help.

ENABLED experimental features:
  $((Get-ExperimentalFeature | Where-Object -not Enabled).Name)
DISABLED experimental features:
  $((Get-ExperimentalFeature | Where-Object Enabled).Name)
"@

It would additionally be helpful if features added since the previous stable release could be highlighted.

For STABLE / LTS versions:

Show only enabled experimental features (if any - see @rkeithhill’s more sophisticated version).

@"
PowerShell 7.2.0-preview.3
Copyright (c) Microsoft Corporation.

https://aka.ms/powershell
Type 'help' to get help.

Enabled experimental features (type 'help about_experimental_features' for help):
  $((Get-ExperimentalFeature | Where-Object -not Enabled).Name)
"@

---

As @DHowett notes, all this extra text should be considered part of the “logo” and should therefore be suppressed if -NoLogo is passed to the CLI.

[DHowett]

If we commit to this, I’d really hope that it’s suppressed by -NoLogo.

[daxian-dbw]

Although I see that users rather prefer not to have a logo. So we are left to consider only the option of a one-time display of information on the first startup. That’s what VS Code does after an upgrade, for example.

@iSazonov Can you please open a new issue describing this idea? Comparing with changing the startup logo, I think it’s a better way to improve the user awareness of the changes in the shell. Please mark it to be reviewed by the “interactive-console” WG.