[program-gen] Fix enum resolution from types of the form Union[string…

…, Enum] and emit fully qualified enum cases (#15696)

# Description

This PR improves enum type resolution from strings. When we try to
resolve `Union[string, Enum]` for a string expression, we choose
`string` because it is the more general type since not every string is
assignable to `Enum`. However, here we spacial case strings that are
actually part of that `Enum`.

The result is that `pcl.LowerConversion` will choose `Enum` from
`Union[string, Enum]` when the value of the input string is compatible
with the enum. This greatly improves program-gen for all of typescript,
python, csharp and go which now will emit the fully qualified enum cases
instead of emitting strings.

Closes pulumi/pulumi-dotnet#41 which is
supposed to be a duplicate of
pulumi/pulumi-azure-native#2616 but that is
not the case (the former is about unions of objects, the latter is
unions of enums and strings)

## Checklist

- [ ] I have run `make tidy` to update any new dependencies
- [x] I have run `make lint` to verify my code passes the lint check
  - [x] I have formatted my code using `gofumpt`

<!--- Please provide details if the checkbox below is to be left
unchecked. -->
- [x] I have added tests that prove my fix is effective or that my
feature works
<!--- 
User-facing changes require a CHANGELOG entry.
-->
- [x] I have run `make changelog` and committed the
`changelog/pending/<file>` documenting my change
<!--
If the change(s) in this PR is a modification of an existing call to the
Pulumi Cloud,
then the service should honor older versions of the CLI where this
change would not exist.
You must then bump the API version in
/pkg/backend/httpstate/client/api.go, as well as add
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- [ ] Yes, there are changes in this PR that warrants bumping the Pulumi
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changelog/pending/20240315--programgen-dotnet-go-nodejs-python--fix-enum-resolution-from-types-of-the-form-union-string-enum.yaml

@@ -0,0 +1,4 @@
+changes:
+- type: fix
+  scope: programgen/dotnet,go,nodejs,python
+  description: Fix enum resolution from types of the form union[string, enum]

pkg/codegen/dotnet/gen_program_expressions.go

@@ -368,6 +368,12 @@ func (g *generator) genSafeEnum(w io.Writer, to *model.EnumType) func(member *sc
 func enumName(enum *model.EnumType) (string, string) {
 	components := strings.Split(enum.Token, ":")
 	contract.Assertf(len(components) == 3, "malformed token %v", enum.Token)
+	modParts := strings.Split(components[1], "/")
+	// if the token has the format {pkg}:{mod}/{name}:{Name}
+	// then we simplify into {pkg}:{mod}:{Name}
+	if len(modParts) == 2 && strings.EqualFold(modParts[1], components[2]) {
+		components[1] = modParts[0]
+	}
 	enumName := tokenToName(enum.Token)
 	e, ok := pcl.GetSchemaForType(enum)
 	if !ok {

pkg/codegen/go/gen_program_expressions.go

@@ -159,7 +159,7 @@ func (g *generator) GenForExpression(w io.Writer, expr *model.ForExpression) {
 	g.genNYI(w, "For expression")
 }
 
-func (g *generator) genSafeEnum(w io.Writer, to *model.EnumType) func(member *schema.Enum) {
+func (g *generator) genSafeEnum(w io.Writer, to *model.EnumType, dest model.Type) func(member *schema.Enum) {
 	return func(member *schema.Enum) {
 		// We know the enum value at the call site, so we can directly stamp in a
 		// valid enum instance. We don't need to convert.
@@ -173,6 +173,14 @@ func (g *generator) genSafeEnum(w io.Writer, to *model.EnumType) func(member *sc
 		pkg, mod, _, _ := pcl.DecomposeToken(to.Token, to.SyntaxNode().Range())
 		mod = g.getModOrAlias(pkg, mod, mod)
 
+		if union, isUnion := dest.(*model.UnionType); isUnion && len(union.Annotations) > 0 {
+			if input, ok := union.Annotations[0].(schema.Type); ok {
+				if _, ok := codegen.ResolvedType(input).(*schema.UnionType); ok {
+					g.Fgenf(w, "pulumi.String(%s.%s)", mod, memberTag)
+					return
+				}
+			}
+		}
 		g.Fgenf(w, "%s.%s", mod, memberTag)
 	}
 }
@@ -206,7 +214,7 @@ func (g *generator) GenFunctionCallExpression(w io.Writer, expr *model.FunctionC
 					from, enumTag, underlyingType)
 				return
 			}
-			diag := pcl.GenEnum(to, from, g.genSafeEnum(w, to), func(from model.Expression) {
+			diag := pcl.GenEnum(to, from, g.genSafeEnum(w, to, expr.Signature.ReturnType), func(from model.Expression) {
 				g.Fgenf(w, "%s(%v)", enumTag, from)
 			})
 			if diag != nil {

pkg/codegen/nodejs/gen_program_expressions.go

@@ -317,6 +317,12 @@ func enumNameWithPackage(enumToken string, pkgRef schema.PackageReference) (stri
 	name := tokenToName(enumToken)
 	pkg := makeValidIdentifier(components[0])
 	if mod := components[1]; mod != "" && mod != "index" {
+		// if the token has the format {pkg}:{mod}/{name}:{Name}
+		// then we simplify into {pkg}:{mod}:{Name}
+		modParts := strings.Split(mod, "/")
+		if len(modParts) == 2 && strings.EqualFold(modParts[1], components[2]) {
+			mod = modParts[0]
+		}
 		if pkgRef != nil {
 			mod = moduleName(mod, pkgRef)
 		}

pkg/codegen/pcl/rewrite_convert.go

@@ -323,6 +323,20 @@ func convertLiteralToString(from model.Expression) (string, bool) {
 	return "", false
 }
 
+func literalExprValue(expr model.Expression) (cty.Value, bool) {
+	if lit, ok := expr.(*model.LiteralValueExpression); ok {
+		return lit.Value, true
+	}
+
+	if templateExpr, ok := expr.(*model.TemplateExpression); ok {
+		if len(templateExpr.Parts) == 1 {
+			return literalExprValue(templateExpr.Parts[0])
+		}
+	}
+
+	return cty.NilVal, false
+}
+
 // lowerConversion performs the main logic of LowerConversion. nil, false is
 // returned if there is no conversion (safe or unsafe) between `from` and `to`.
 // This can occur when a loosely typed program is converted, or if an other
@@ -332,6 +346,19 @@ func lowerConversion(from model.Expression, to model.Type) (model.Type, bool) {
 	case *model.UnionType:
 		// Assignment: it just works
 		for _, to := range to.ElementTypes {
+			// in general, strings are not assignable to enums, but we allow it here
+			// if the enum has an element that matches the `from` expression
+			switch enumType := to.(type) {
+			case *model.EnumType:
+				if literal, ok := literalExprValue(from); ok {
+					for _, enumCase := range enumType.Elements {
+						if enumCase.RawEquals(literal) {
+							return to, true
+						}
+					}
+				}
+			}
+
 			if to.AssignableFrom(from.Type()) {
 				return to, true
 			}

pkg/codegen/python/gen_program_expressions.go

@@ -243,10 +243,14 @@ func (g *generator) GenFunctionCallExpression(w io.Writer, expr *model.FunctionC
 				moduleNameOverrides = pkg.Language["python"].(PackageInfo).ModuleNameOverrides
 			}
 			pkg := strings.ReplaceAll(components[0], "-", "_")
+			enumName := tokenToName(to.Token)
 			if m := tokenToModule(to.Token, nil, moduleNameOverrides); m != "" {
-				pkg += "." + m
+				modParts := strings.Split(m, "/")
+				if len(modParts) == 2 && strings.EqualFold(modParts[1], enumName) {
+					m = modParts[0]
+				}
+				pkg += "." + strings.ReplaceAll(m, "/", ".")
 			}
-			enumName := tokenToName(to.Token)
 
 			if isOutput {
 				g.Fgenf(w, "%.v.apply(lambda x: %s.%s(x))", from, pkg, enumName)

pkg/codegen/testing/test/program_driver.go

@@ -158,6 +158,13 @@ var PulumiPulumiProgramTests = []ProgramTest{
 		Directory:   "azure-sa",
 		Description: "Azure SA",
 	},
+	{
+		Directory:   "string-enum-union-list",
+		Description: "Contains resource which has a property of type List<Union<String, Enum>>",
+		// skipping compiling on Go because it doesn't know to handle unions in lists
+		// and instead generates pulumi.StringArray
+		SkipCompile: codegen.NewStringSet("go"),
+	},
 	{
 		Directory:   "kubernetes-operator",
 		Description: "K8s Operator",

tests/testdata/codegen/aws-lambda-pp/python/aws-lambda.py

@@ -6,7 +6,7 @@
     code=pulumi.FileArchive("lambda_function_payload.zip"),
     role=iam_for_lambda.arn,
     handler="index.test",
-    runtime="nodejs12.x",
+    runtime=aws.lambda_.Runtime.NODE_JS12D_X,
     environment=aws.lambda_.FunctionEnvironmentArgs(
         variables={
             "foo": "bar",

tests/testdata/codegen/aws-webserver-pp/dotnet/aws-webserver.cs

@@ -51,7 +51,7 @@
         {
             { "Name", "web-server-www" },
         },
-        InstanceType = "t2.micro",
+        InstanceType = Aws.Ec2.InstanceType.T2_Micro,
         SecurityGroups = new[]
         {
             securityGroup.Name,

tests/testdata/codegen/aws-webserver-pp/go/aws-webserver.go

@@ -47,7 +47,7 @@ func main() {
 			Tags: pulumi.StringMap{
 				"Name": pulumi.String("web-server-www"),
 			},
-			InstanceType: pulumi.String("t2.micro"),
+			InstanceType: pulumi.String(ec2.InstanceType_T2_Micro),
 			SecurityGroups: pulumi.StringArray{
 				securityGroup.Name,
 			},

tests/testdata/codegen/aws-webserver-pp/nodejs/aws-webserver.ts

@@ -22,7 +22,7 @@ const server = new aws.ec2.Instance("server", {
     tags: {
         Name: "web-server-www",
     },
-    instanceType: "t2.micro",
+    instanceType: aws.ec2.InstanceType.T2_Micro,
     securityGroups: [securityGroup.name],
     ami: ami.then(ami => ami.id),
     userData: `#!/bin/bash

tests/testdata/codegen/aws-webserver-pp/python/aws-webserver.py

@@ -20,7 +20,7 @@
     tags={
         "Name": "web-server-www",
     },
-    instance_type="t2.micro",
+    instance_type=aws.ec2.InstanceType.T2_MICRO,
     security_groups=[security_group.name],
     ami=ami.id,
     user_data="""#!/bin/bash

tests/testdata/codegen/azure-native-1.56.0.json

@@ -426994,7 +426994,14 @@
         "rights": {
           "type": "array",
           "items": {
-            "$ref": "#/types/azure-native:servicebus:AccessRights"
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "$ref": "#/types/azure-native:servicebus:AccessRights"
+              }
+            ]
           },
           "description": "The rights associated with the rule."
         }

tests/testdata/codegen/azure-native-pp/dotnet/azure-native.cs

@@ -40,9 +40,9 @@
                             Name = "CacheExpiration",
                             Parameters = new AzureNative.Cdn.Inputs.CacheExpirationActionParametersArgs
                             {
-                                CacheBehavior = "Override",
+                                CacheBehavior = AzureNative.Cdn.CacheBehavior.Override,
                                 CacheDuration = "10:10:09",
-                                CacheType = "All",
+                                CacheType = AzureNative.Cdn.CacheType.All,
                                 OdataType = "#Microsoft.Azure.Cdn.Models.DeliveryRuleCacheExpirationActionParameters",
                             },
                         },
@@ -51,7 +51,7 @@
                             Name = "ModifyResponseHeader",
                             Parameters = new AzureNative.Cdn.Inputs.HeaderActionParametersArgs
                             {
-                                HeaderAction = "Overwrite",
+                                HeaderAction = AzureNative.Cdn.HeaderAction.Overwrite,
                                 HeaderName = "Access-Control-Allow-Origin",
                                 OdataType = "#Microsoft.Azure.Cdn.Models.DeliveryRuleHeaderActionParameters",
                                 Value = "*",
@@ -62,7 +62,7 @@
                             Name = "ModifyRequestHeader",
                             Parameters = new AzureNative.Cdn.Inputs.HeaderActionParametersArgs
                             {
-                                HeaderAction = "Overwrite",
+                                HeaderAction = AzureNative.Cdn.HeaderAction.Overwrite,
                                 HeaderName = "Accept-Encoding",
                                 OdataType = "#Microsoft.Azure.Cdn.Models.DeliveryRuleHeaderActionParameters",
                                 Value = "gzip",
@@ -83,7 +83,7 @@
                                 },
                                 NegateCondition = true,
                                 OdataType = "#Microsoft.Azure.Cdn.Models.DeliveryRuleRemoteAddressConditionParameters",
-                                Operator = "IPMatch",
+                                Operator = AzureNative.Cdn.RemoteAddressOperator.IPMatch,
                             },
                         },
                     },

tests/testdata/codegen/azure-native-pp/go/azure-native.go

@@ -33,16 +33,16 @@ func main() {
 							{
 								Name: "CacheExpiration",
 								Parameters: {
-									CacheBehavior: "Override",
+									CacheBehavior: cdn.CacheBehaviorOverride,
 									CacheDuration: "10:10:09",
-									CacheType:     "All",
+									CacheType:     cdn.CacheTypeAll,
 									OdataType:     "#Microsoft.Azure.Cdn.Models.DeliveryRuleCacheExpirationActionParameters",
 								},
 							},
 							{
 								Name: "ModifyResponseHeader",
 								Parameters: {
-									HeaderAction: "Overwrite",
+									HeaderAction: cdn.HeaderActionOverwrite,
 									HeaderName:   "Access-Control-Allow-Origin",
 									OdataType:    "#Microsoft.Azure.Cdn.Models.DeliveryRuleHeaderActionParameters",
 									Value:        "*",
@@ -51,7 +51,7 @@ func main() {
 							{
 								Name: "ModifyRequestHeader",
 								Parameters: {
-									HeaderAction: "Overwrite",
+									HeaderAction: cdn.HeaderActionOverwrite,
 									HeaderName:   "Accept-Encoding",
 									OdataType:    "#Microsoft.Azure.Cdn.Models.DeliveryRuleHeaderActionParameters",
 									Value:        "gzip",
@@ -68,7 +68,7 @@ func main() {
 									},
 									NegateCondition: true,
 									OdataType:       "#Microsoft.Azure.Cdn.Models.DeliveryRuleRemoteAddressConditionParameters",
-									Operator:        "IPMatch",
+									Operator:        cdn.RemoteAddressOperatorIPMatch,
 								},
 							},
 						},

tests/testdata/codegen/azure-native-pp/nodejs/azure-native.ts

@@ -20,16 +20,16 @@ const endpoint = new azure_native.cdn.Endpoint("endpoint", {
                 {
                     name: "CacheExpiration",
                     parameters: {
-                        cacheBehavior: "Override",
+                        cacheBehavior: azure_native.cdn.CacheBehavior.Override,
                         cacheDuration: "10:10:09",
-                        cacheType: "All",
+                        cacheType: azure_native.cdn.CacheType.All,
                         odataType: "#Microsoft.Azure.Cdn.Models.DeliveryRuleCacheExpirationActionParameters",
                     },
                 },
                 {
                     name: "ModifyResponseHeader",
                     parameters: {
-                        headerAction: "Overwrite",
+                        headerAction: azure_native.cdn.HeaderAction.Overwrite,
                         headerName: "Access-Control-Allow-Origin",
                         odataType: "#Microsoft.Azure.Cdn.Models.DeliveryRuleHeaderActionParameters",
                         value: "*",
@@ -38,7 +38,7 @@ const endpoint = new azure_native.cdn.Endpoint("endpoint", {
                 {
                     name: "ModifyRequestHeader",
                     parameters: {
-                        headerAction: "Overwrite",
+                        headerAction: azure_native.cdn.HeaderAction.Overwrite,
                         headerName: "Accept-Encoding",
                         odataType: "#Microsoft.Azure.Cdn.Models.DeliveryRuleHeaderActionParameters",
                         value: "gzip",
@@ -54,7 +54,7 @@ const endpoint = new azure_native.cdn.Endpoint("endpoint", {
                     ],
                     negateCondition: true,
                     odataType: "#Microsoft.Azure.Cdn.Models.DeliveryRuleRemoteAddressConditionParameters",
-                    operator: "IPMatch",
+                    operator: azure_native.cdn.RemoteAddressOperator.IPMatch,
                 },
             }],
             name: "rule1",

tests/testdata/codegen/azure-native-pp/python/azure-native.py

@@ -19,16 +19,16 @@
                 azure_native.cdn.DeliveryRuleCacheExpirationActionArgs(
                     name="CacheExpiration",
                     parameters=azure_native.cdn.CacheExpirationActionParametersArgs(
-                        cache_behavior="Override",
+                        cache_behavior=azure_native.cdn.CacheBehavior.OVERRIDE,
                         cache_duration="10:10:09",
-                        cache_type="All",
+                        cache_type=azure_native.cdn.CacheType.ALL,
                         odata_type="#Microsoft.Azure.Cdn.Models.DeliveryRuleCacheExpirationActionParameters",
                     ),
                 ),
                 azure_native.cdn.DeliveryRuleResponseHeaderActionArgs(
                     name="ModifyResponseHeader",
                     parameters=azure_native.cdn.HeaderActionParametersArgs(
-                        header_action="Overwrite",
+                        header_action=azure_native.cdn.HeaderAction.OVERWRITE,
                         header_name="Access-Control-Allow-Origin",
                         odata_type="#Microsoft.Azure.Cdn.Models.DeliveryRuleHeaderActionParameters",
                         value="*",
@@ -37,7 +37,7 @@
                 azure_native.cdn.DeliveryRuleRequestHeaderActionArgs(
                     name="ModifyRequestHeader",
                     parameters=azure_native.cdn.HeaderActionParametersArgs(
-                        header_action="Overwrite",
+                        header_action=azure_native.cdn.HeaderAction.OVERWRITE,
                         header_name="Accept-Encoding",
                         odata_type="#Microsoft.Azure.Cdn.Models.DeliveryRuleHeaderActionParameters",
                         value="gzip",
@@ -53,7 +53,7 @@
                     ],
                     negate_condition=True,
                     odata_type="#Microsoft.Azure.Cdn.Models.DeliveryRuleRemoteAddressConditionParameters",
-                    operator="IPMatch",
+                    operator=azure_native.cdn.RemoteAddressOperator.IP_MATCH,
                 ),
             )],
             name="rule1",

tests/testdata/codegen/discriminated-union-pp/dotnet/discriminated-union.cs

@@ -21,7 +21,7 @@
             Capacity = 2,
             Family = "Gen5",
             Name = "B_Gen5_2",
-            Tier = "Basic",
+            Tier = AzureNative.DBforPostgreSQL.SkuTier.Basic,
         },
         Tags = 
         {

tests/testdata/codegen/discriminated-union-pp/nodejs/discriminated-union.ts

@@ -14,7 +14,7 @@ const server = new azure_native.dbforpostgresql.Server("server", {
         capacity: 2,
         family: "Gen5",
         name: "B_Gen5_2",
-        tier: "Basic",
+        tier: azure_native.dbforpostgresql.SkuTier.Basic,
     },
     tags: {
         ElasticServer: "1",

tests/testdata/codegen/discriminated-union-pp/python/discriminated-union.py

@@ -14,7 +14,7 @@
         capacity=2,
         family="Gen5",
         name="B_Gen5_2",
-        tier="Basic",
+        tier=azure_native.dbforpostgresql.SkuTier.BASIC,
     ),
     tags={
         "ElasticServer": "1",

tests/testdata/codegen/empty-list-property-pp/dotnet/empty-list-property.cs

@@ -8,12 +8,12 @@
     var storageAccounts = new AzureNative.Storage.StorageAccount("storageAccounts", new()
     {
         AccountName = "sto4445",
-        Kind = "BlockBlobStorage",
+        Kind = AzureNative.Storage.Kind.BlockBlobStorage,
         Location = "eastus",
         ResourceGroupName = "res9101",
         Sku = new AzureNative.Storage.Inputs.SkuArgs
         {
-            Name = "Premium_LRS",
+            Name = AzureNative.Storage.SkuName.Premium_LRS,
         },
         NetworkRuleSet = new AzureNative.Storage.Inputs.NetworkRuleSetArgs
         {