Detailed diff for set element changes shows more additions/removals than present

[VenelinMartinov]

What happened?

changing "setProps": []interface{}{"val2", "val3"} to "setProps": []interface{}{"val1", "val2", "val3"} produces:

  ~ prov:index/test:Test: (update)
      [id=newid]
      [urn=urn:pulumi:test::test::prov:index/test:Test::mainRes]
    ~ setProps: [
        + [0]: "val1"
        ~ [1]: "val3" => "val2"
        + [2]: "val3"
      ]

The detailed diff shows 2 elements added and 1 changed but only 1 element was added.

Similarly:

Changing "setProps": []interface{}{"val1", "val2", "val3"} to "setProps": []interface{}{"val1", "val3"} produces:

  ~ prov:index/test:Test: (update)
      [id=newid]
      [urn=urn:pulumi:test::test::prov:index/test:Test::mainRes]
    ~ setProps: [
          [0]: "val1"
        - [1]: "val2"
        - [2]: "val3"
      ]

Which shows 2 elements being removed but only 1 was removed

Example

https://github.com/pulumi/pulumi-terraform-bridge/pull/2159/files

set element removed middle and set element added front

Output of pulumi about

.

Additional context

No response

Contributing

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[t0yv0]

Here's an AWS example to illustrate:

import * as pulumi from "@pulumi/pulumi";
import * as aws from "@pulumi/aws";

const cfg = new pulumi.Config();
const step = cfg.requireNumber("step");

console.log("step", step);

const current = aws.s3.getCanonicalUserId({});

const example = new aws.s3.BucketV2("example");

const exampleBucketOwnershipControls = new aws.s3.BucketOwnershipControls("example", {
    bucket: example.id,
    rule: {
        objectOwnership: "BucketOwnerPreferred",
    },
});

const exampleBucketAclV2 = new aws.s3.BucketAclV2("example-bucket", {
    bucket: example.id,
    accessControlPolicy: {
        grants: (step === 0) ? [
            {
                grantee: {
                    id: current.then(current => current.id),
                    type: "CanonicalUser",
                },
                permission: "READ_ACP",
            },
            {
                grantee: {
                    type: "Group",
                    uri: "http://acs.amazonaws.com/groups/s3/LogDelivery",
                },
                permission: "READ_ACP",
            },
        ] : [
            {
                grantee: {
                    id: current.then(current => current.id),
                    type: "CanonicalUser",
                },
                permission: "READ_ACP",
            },
            {
                grantee: {
                    type: "Group",
                    uri: "http://acs.amazonaws.com/groups/s3/LogDelivery2",
                },
                permission: "READ",
            },
            {
                grantee: {
                    type: "Group",
                    uri: "http://acs.amazonaws.com/groups/s3/LogDelivery",
                },
                permission: "READ_ACP",
            },
        ],
        owner: {
            id: current.then(current => current.id),
        },
    },
}, {
    dependsOn: [exampleBucketOwnershipControls],
    // ignoreChanges: step === 0 ? [] : ["accessControlPolicy.grants[0].permission"]
});

export const bucketId = exampleBucketAclV2.id;

Repro:

#!/usr/bin/env bash

set -euo pipefail

pulumi destroy --yes
pulumi config set step 0
pulumi up --yes --skip-preview
pulumi config set step 1
rm "$PWD/preview.json"
rm "$PWD/up.json"
PULUMI_DEBUG_GRPC="$PWD/preview.json" pulumi preview --diff
PULUMI_DEBUG_GRPC="$PWD/up.json" pulumi up --yes --skip-preview

Shows this diff:

    ~ aws:s3/bucketAclV2:BucketAclV2: (update)
        [id=example-a331d64]
        [urn=urn:pulumi:dev::e1::aws:s3/bucketAclV2:BucketAclV2::example-bucket]
        [provider=urn:pulumi:dev::e1::pulumi:providers:aws::default_6_45_0::153e26c0-d2dc-484a-b5c2-15b17d914601]
      ~ accessControlPolicy: {
          ~ grants: [
              ~ [0]: {
                      + __defaults: []
                      ~ grantee   : {
                          + __defaults  : []
                          - displayName : ""
                          - emailAddress: ""
                          + id          : "e07865a5679c7977370948f1f1e51c21b12d8cfdd396a7e3172275d9164e01b8"
                          ~ type        : "Group" => "CanonicalUser"
                          - uri         : "http://acs.amazonaws.com/groups/s3/LogDelivery"
                        }
                        permission: "READ_ACP"
                    }
              ~ [1]: {
                      + __defaults: []
                      ~ grantee   : {
                          + __defaults  : []
                          - displayName : "aws-contact+dev-sandbox"
                          - emailAddress: ""
                          - id          : "e07865a5679c7977370948f1f1e51c21b12d8cfdd396a7e3172275d9164e01b8"
                          ~ type        : "CanonicalUser" => "Group"
                          + uri         : "http://acs.amazonaws.com/groups/s3/LogDelivery2"
                        }
                      ~ permission: "READ_ACP" => "READ"
                    }
              + [2]: {
                      + grantee   : {
                          + type      : "Group"
                          + uri       : "http://acs.amazonaws.com/groups/s3/LogDelivery"
                        }
                      + permission: "READ_ACP"
                    }
            ]
        }

[t0yv0]

The desired diff would simply show that this element got added:

  {
                grantee: {
                    type: "Group",
                    uri: "http://acs.amazonaws.com/groups/s3/LogDelivery2",
                },
                permission: "READ",
            },

[t0yv0]

This is excellent to track in addition to #186 that talks about in-place changes to set elements. The issue tracked here is an addition or removal of elements and not an in-place change.

I think we should be able to address both classes of issues along the lines outlined in #2200