PRC issue with detailed diff with unknown element in a set

[VenelinMartinov]

What happened?

Under PRC we fail to display a sensible detailed diff when a set contains an unknown element:

Previewing update (test):
  pulumi:pulumi:Stack: (same)
    [urn=urn:pulumi:test::test::pulumi:pulumi:Stack::test-test]
    + prov:index/aux:Aux: (create)
        [urn=urn:pulumi:test::test::prov:index/aux:Aux::auxRes]
    ~ prov:index/test:Test: (update)
        [id=newid]
        [urn=urn:pulumi:test::test::prov:index/test:Test::mainRes]
    --outputs:--
  + testOut: output<string>
Resources:
    + 1 to create
    ~ 1 to update
    2 changes. 1 unchanged

vs

Previewing update (test):
  pulumi:pulumi:Stack: (same)
    [urn=urn:pulumi:test::test::pulumi:pulumi:Stack::test-test]
    + prov:index/aux:Aux: (create)
        [urn=urn:pulumi:test::test::prov:index/aux:Aux::auxRes]
    ~ prov:index/test:Test: (update)
        [id=newid]
        [urn=urn:pulumi:test::test::prov:index/test:Test::mainRes]
      + tests: [
      +     [0]: output<string>
        ]
    --outputs:--
  + testOut: output<string>
Resources:
    + 1 to create
    ~ 1 to update
    2 changes. 1 unchanged

Example

TestUnknownSetElementDiff/PRC_enabled

Output of pulumi about

.

Additional context

No response

Contributing

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[t0yv0]

Looks like this regressed but feels mostly cosmetic. I wonder what the baseline TF behavior is for these cases. We can clean htis up as part of the accurate previews epic thank you.

[pulumi-bot]

This issue has been addressed in PR #2405 and shipped in release v3.92.0.