Remove experimental flag for SkipDetailedDiff (#1893)

Removes the flag option `XSkipDetailedDiffForChanges` and rolls out
behavior to all providers.

This change will break the next bridge release for pulumi-gcp and
pulumi-aws. When updating those providers to these changes, the
`XSkipDetailedDiffForChanges` provider info option must be removed.

Note that the maxItemsOne migration tests needed to be updated to show
that a change of `[]` to `""` reflects a diff on the field in question
now. This makes sense to me, since a nil slice is different from an
empty string, but this may actually not be desired behavior, so I'd
appreciate scrutiny here. Either way, the functionality under test there
requires a diff to happen on MaxItemsOne migrations and that does not
change.

Fixes #1501.

pkg/tfbridge/diff_test.go

@@ -2071,14 +2071,13 @@ func TestListNestedAddMaxItemsOne(t *testing.T) {
 }
 
 type diffTestCase struct {
-	resourceSchema              map[string]*schema.Schema
-	resourceFields              map[string]*SchemaInfo
-	state                       resource.PropertyMap
-	inputs                      resource.PropertyMap
-	expected                    map[string]*pulumirpc.PropertyDiff
-	expectedDiffChanges         pulumirpc.DiffResponse_DiffChanges
-	ignoreChanges               []string
-	XSkipDetailedDiffForChanges bool
+	resourceSchema      map[string]*schema.Schema
+	resourceFields      map[string]*SchemaInfo
+	state               resource.PropertyMap
+	inputs              resource.PropertyMap
+	expected            map[string]*pulumirpc.PropertyDiff
+	expectedDiffChanges pulumirpc.DiffResponse_DiffChanges
+	ignoreChanges       []string
 }
 
 func diffTest2(t *testing.T, tc diffTestCase) {
@@ -2100,7 +2099,6 @@ func diffTest2(t *testing.T, tc diffTestCase) {
 	p := Provider{
 		tf: provider,
 		info: ProviderInfo{
-			XSkipDetailedDiffForChanges: tc.XSkipDetailedDiffForChanges,
 			Resources: map[string]*ResourceInfo{
 				"p_resource": {
 					Tok:    "pkg:index:PResource",
@@ -2151,8 +2149,7 @@ func TestChangingMaxItems1FilterProperty(t *testing.T) {
 		},
 	}
 	diffTest2(t, diffTestCase{
-		XSkipDetailedDiffForChanges: true,
-		resourceSchema:              schema,
+		resourceSchema: schema,
 		state: resource.PropertyMap{
 			"rules": resource.NewArrayProperty(
 				[]resource.PropertyValue{

pkg/tfbridge/info/info.go

@@ -151,11 +151,6 @@ type Provider struct {
 	// See also: pulumi/pulumi-terraform-bridge#1448
 	SkipValidateProviderConfigForPluginFramework bool
 
-	// Disables using detailed diff to determine diff changes and falls back on the length of TF Diff Attributes.
-	//
-	// See https://github.com/pulumi/pulumi-terraform-bridge/issues/1501
-	XSkipDetailedDiffForChanges bool
-
 	// Enables generation of a trimmed, runtime-only metadata file
 	// to help reduce resource plugin start time
 	//

pkg/tfbridge/provider.go

@@ -926,7 +926,7 @@ func (p *Provider) Diff(ctx context.Context, req *pulumirpc.DiffRequest) (*pulum
 	// We will still use `detailedDiff` for diff display purposes.
 
 	// See also https://github.com/pulumi/pulumi-terraform-bridge/issues/1501.
-	if p.info.XSkipDetailedDiffForChanges && len(diff.Attributes()) > 0 {
+	if len(diff.Attributes()) > 0 {
 		changes = pulumirpc.DiffResponse_DIFF_SOME
 		// Perhaps collectionDiffs can shed some light and locate the changes to the end-user.
 		for path, diff := range dd.collectionDiffs {

pkg/tfbridge/provider_test.go

@@ -2156,9 +2156,6 @@ func TestSkipDetailedDiff(t *testing.T) {
 					Schema: &ResourceInfo{Tok: "Replace"},
 				},
 			},
-			info: ProviderInfo{
-				XSkipDetailedDiffForChanges: skipDetailedDiffForChanges,
-			},
 		}
 	}
 	t.Run("Diff", func(t *testing.T) {
@@ -2432,7 +2429,7 @@ func TestMaxItemOneWrongStateDiff(t *testing.T) {
 				"urn": "urn:pulumi:dev::teststack::NestedStrRes::exres",
 				"id": "0",
 				"olds": {
-					"nested_str": []
+					"nested_str": [""]
 				},
 				"news": {
 					"nested_str": ""
@@ -2444,6 +2441,32 @@ func TestMaxItemOneWrongStateDiff(t *testing.T) {
 			}
 		}`)
 	})
+	t.Run("DiffNilListAndVal", func(t *testing.T) {
+		testutils.Replay(t, provider, `
+		{
+			"method": "/pulumirpc.ResourceProvider/Diff",
+			"request": {
+				"urn": "urn:pulumi:dev::teststack::NestedStrRes::exres",
+				"id": "0",
+				"olds": {
+					"nested_str": []
+				},
+				"news": {
+					"nested_str": ""
+				}
+			},
+			"response": {
+				"changes": "DIFF_SOME",
+				"hasDetailedDiff": true,
+				"detailedDiff": {
+					"nested_str": {
+						"kind": "UPDATE"
+					}
+				},
+				"diffs": ["nested_str"]
+			}
+		}`)
+	})
 	t.Run("DiffListAndValNonEmpty", func(t *testing.T) {
 		testutils.Replay(t, provider, `
 		{