feat: add Positional trait support in Go codegen

TestModels/Positional/Makefile

@@ -46,3 +46,8 @@ INDEX_FILE_WITHOUT_EXTERN_STRING="module SimplePositional refines AbstractSimple
 WRAPPED_INDEX_FILE_PATH=src/WrappedSimplePositionalImpl.dfy
 WRAPPED_INDEX_FILE_WITH_EXTERN_STRING="module {:options \"--function-syntax:4\"} {:extern \"simple.positional.internaldafny.wrapped\"} WrappedSimplePositionalService refines WrappedAbstractSimplePositionalService {"
 WRAPPED_INDEX_FILE_WITHOUT_EXTERN_STRING="module {:options \"--function-syntax:4\"} WrappedSimplePositionalService refines WrappedAbstractSimplePositionalService {"
+
+GO_MODULE_NAME="github.com/smithy-lang/smithy-dafny/TestModels/Positional"
+
+TRANSLATION_RECORD_GO := \
+    dafny-dependencies/StandardLibrary/runtimes/go/ImplementationFromDafny-go/ImplementationFromDafny-go.dtr

TestModels/Positional/runtimes/go/ImplementationFromDafny-go/go.mod

@@ -0,0 +1,10 @@
+module github.com/smithy-lang/smithy-dafny/TestModels/Positional
+
+go 1.23.0
+
+require (
+	github.com/dafny-lang/DafnyRuntimeGo/v4 v4.8.0
+	github.com/dafny-lang/DafnyStandardLibGo v0.0.0
+)
+
+replace github.com/dafny-lang/DafnyStandardLibGo => ../../../../dafny-dependencies/StandardLibrary/runtimes/go/ImplementationFromDafny-go/

TestModels/Positional/runtimes/go/TestsFromDafny-go/go.mod

@@ -0,0 +1,14 @@
+module github.com/smithy-lang/smithy-dafny/TestModels/Positional/test
+
+go 1.23.0
+
+require github.com/dafny-lang/DafnyStandardLibGo v0.0.0
+
+require (
+	github.com/dafny-lang/DafnyRuntimeGo/v4 v4.8.0
+	github.com/smithy-lang/smithy-dafny/TestModels/Positional v0.0.0
+)
+
+replace github.com/smithy-lang/smithy-dafny/TestModels/Positional v0.0.0 => ../ImplementationFromDafny-go
+
+replace github.com/dafny-lang/DafnyStandardLibGo => ../../../../dafny-dependencies/StandardLibrary/runtimes/go/ImplementationFromDafny-go/

codegen/smithy-dafny-codegen-test/src/test/java/software/amazon/polymorph/smithygo/GoTestModels.java

@@ -35,9 +35,6 @@ class GoTestModels extends TestModelTest {
     DISABLED_TESTS.add("MultipleModels");
     DISABLED_TESTS.add("LocalService");
 
-    //TODO: Pending PR Merge
-    DISABLED_TESTS.add("Positional");
-
     //V1 Tests are not supported in Go
     DISABLED_TESTS.add("aws-sdks/ddb");
     DISABLED_TESTS.add("aws-sdks/kms");

codegen/smithy-dafny-codegen/src/main/java/software/amazon/polymorph/smithygo/localservice/DafnyLocalServiceGenerator.java

@@ -17,8 +17,10 @@
 import software.amazon.polymorph.smithygo.localservice.nameresolver.SmithyNameResolver;
 import software.amazon.polymorph.traits.ExtendableTrait;
 import software.amazon.polymorph.traits.LocalServiceTrait;
+import software.amazon.polymorph.traits.PositionalTrait;
 import software.amazon.polymorph.traits.ReferenceTrait;
 import software.amazon.smithy.aws.traits.ServiceTrait;
+import software.amazon.smithy.codegen.core.Symbol;
 import software.amazon.smithy.codegen.core.SymbolProvider;
 import software.amazon.smithy.model.Model;
 import software.amazon.smithy.model.knowledge.TopDownIndex;
@@ -212,7 +214,7 @@ func NewClient(clientConfig $L) (*$T, error) {
               SmithyNameResolver.smithyTypesNamespace(inputShape),
               inputShape.toShapeId().getName()
             );
-        final var outputType = outputShape.hasTrait(UnitTypeTrait.class)
+        var outputType = outputShape.hasTrait(UnitTypeTrait.class)
           ? ""
           : "*%s.%s,".formatted(
               SmithyNameResolver.smithyTypesNamespace(outputShape),
@@ -241,15 +243,38 @@ func NewClient(clientConfig $L) (*$T, error) {
                 operationShape.getId().getName()
               );
         } else {
+          String dafnyType;
+          if (inputShape.hasTrait(PositionalTrait.class)) {
+            Shape inputForPositional = model.expectShape(
+              inputShape
+                .getAllMembers()
+                .values()
+                .stream()
+                .findFirst()
+                .get()
+                .getTarget()
+            );
+            Symbol symbolForPositional = symbolProvider.toSymbol(
+              inputForPositional
+            );
+            dafnyType =
+              DafnyNameResolver.getDafnyType(
+                inputForPositional,
+                symbolForPositional
+              );
+          } else {
+            dafnyType =
+              DafnyNameResolver.getDafnyType(
+                inputShape,
+                symbolProvider.toSymbol(inputShape)
+              );
+          }
           baseClientCall =
             """
             var dafny_request %s = %s(params)
             var dafny_response = client.DafnyClient.%s(dafny_request)
             """.formatted(
-                DafnyNameResolver.getDafnyType(
-                  inputShape,
-                  symbolProvider.toSymbol(inputShape)
-                ),
+                dafnyType,
                 SmithyNameResolver.getToDafnyMethodName(
                   service,
                   inputShape,
@@ -264,21 +289,30 @@ func NewClient(clientConfig $L) (*$T, error) {
           returnResponse = "return nil";
           returnError = "return";
         } else {
-          returnResponse =
-            """
-            var native_response = %s(dafny_response.Extract().(%s))
-            return &native_response, nil
-            """.formatted(
-                SmithyNameResolver.getFromDafnyMethodName(
-                  service,
-                  outputShape,
-                  ""
-                ),
-                DafnyNameResolver.getDafnyType(
-                  outputShape,
-                  symbolProvider.toSymbol(outputShape)
-                )
-              );
+          if (outputShape.hasTrait(PositionalTrait.class)) {
+            outputType = "interface{},";
+            returnResponse =
+              """
+                  var native_response = dafny_response.Extract()
+                  return native_response, nil
+              """;
+          } else {
+            returnResponse =
+              """
+              var native_response = %s(dafny_response.Extract().(%s))
+              return &native_response, nil
+              """.formatted(
+                  SmithyNameResolver.getFromDafnyMethodName(
+                    service,
+                    outputShape,
+                    ""
+                  ),
+                  DafnyNameResolver.getDafnyType(
+                    outputShape,
+                    symbolProvider.toSymbol(outputShape)
+                  )
+                );
+          }
           returnError = "return nil,";
         }
 
@@ -396,15 +430,16 @@ void generateShim() {
             final var outputShape = model.expectShape(
               operationShape.getOutputShape()
             );
-            final var inputType = inputShape.hasTrait(UnitTypeTrait.class)
+            // this is maybe because positional trait can change this
+            final var maybeInputType = inputShape.hasTrait(UnitTypeTrait.class)
               ? ""
               : "input %s".formatted(
                   DafnyNameResolver.getDafnyType(
                     inputShape,
                     symbolProvider.toSymbol(inputShape)
                   )
                 );
-
+            final String inputType;
             final var typeConversion = inputShape.hasTrait(UnitTypeTrait.class)
               ? ""
               : "var native_request = %s(input)".formatted(
@@ -434,6 +469,32 @@ void generateShim() {
                     SmithyNameResolver.getToDafnyMethodName(outputShape, "")
                   );
             }
+            if (inputShape.hasTrait(PositionalTrait.class)) {
+              writer.addImportFromModule(
+                "github.com/dafny-lang/DafnyRuntimeGo",
+                "dafny"
+              );
+              Shape inputForPositional = model.expectShape(
+                inputShape
+                  .getAllMembers()
+                  .values()
+                  .stream()
+                  .findFirst()
+                  .get()
+                  .getTarget()
+              );
+              Symbol symbolForPositional = symbolProvider.toSymbol(
+                inputForPositional
+              );
+              String dafnyType = DafnyNameResolver.getDafnyType(
+                inputForPositional,
+                symbolForPositional
+              );
+              inputType = "input %s".formatted(dafnyType);
+              returnResponse = "(native_response)";
+            } else {
+              inputType = maybeInputType;
+            }
 
             writer.write(
               """

codegen/smithy-dafny-codegen/src/main/java/software/amazon/polymorph/smithygo/localservice/DafnyLocalServiceTypeConversionProtocol.java

@@ -22,11 +22,14 @@
 import software.amazon.polymorph.smithygo.utils.GoCodegenUtils;
 import software.amazon.polymorph.traits.ExtendableTrait;
 import software.amazon.polymorph.traits.LocalServiceTrait;
+import software.amazon.polymorph.traits.PositionalTrait;
 import software.amazon.polymorph.traits.ReferenceTrait;
 import software.amazon.smithy.aws.traits.ServiceTrait;
+import software.amazon.smithy.codegen.core.Symbol;
 import software.amazon.smithy.model.shapes.OperationShape;
 import software.amazon.smithy.model.shapes.ResourceShape;
 import software.amazon.smithy.model.shapes.ServiceShape;
+import software.amazon.smithy.model.shapes.Shape;
 import software.amazon.smithy.model.shapes.ShapeId;
 import software.amazon.smithy.model.shapes.StructureShape;
 import software.amazon.smithy.model.traits.ErrorTrait;
@@ -78,6 +81,29 @@ public void generateSerializers(final GenerationContext context) {
             final var inputToDafnyMethodName =
               SmithyNameResolver.getToDafnyMethodName(serviceShape, input, "");
             final var inputSymbol = symbolProvider.toSymbol(input);
+            final String outputType;
+            if (input.hasTrait(PositionalTrait.class)) {
+              // Output type in To Dafny should be unwrapped
+              Shape inputForPositional = model.expectShape(
+                input
+                  .getAllMembers()
+                  .values()
+                  .stream()
+                  .findFirst()
+                  .get()
+                  .getTarget()
+              );
+              Symbol symbolForPositional = symbolProvider.toSymbol(
+                inputForPositional
+              );
+              outputType =
+                DafnyNameResolver.getDafnyType(
+                  inputForPositional,
+                  symbolForPositional
+                );
+            } else {
+              outputType = DafnyNameResolver.getDafnyType(input, inputSymbol);
+            }
             writerDelegator.useFileWriter(
               "%s/%s".formatted(
                   SmithyNameResolver.shapeNamespace(serviceShape),
@@ -98,7 +124,7 @@ public void generateSerializers(final GenerationContext context) {
                   }""",
                   inputToDafnyMethodName,
                   SmithyNameResolver.getSmithyType(input, inputSymbol),
-                  DafnyNameResolver.getDafnyType(input, inputSymbol),
+                  outputType,
                   writer.consumer(w ->
                     generateRequestSerializer(
                       context,
@@ -113,7 +139,10 @@ public void generateSerializers(final GenerationContext context) {
         }
 
         final var output = model.expectShape(operation.getOutputShape());
-        if (!alreadyVisited.contains(output.toShapeId())) {
+        if (
+          !alreadyVisited.contains(output.toShapeId()) &&
+          !output.hasTrait(PositionalTrait.class)
+        ) {
           alreadyVisited.add(output.toShapeId());
           if (
             !output.hasTrait(UnitTypeTrait.class) &&
@@ -370,6 +399,31 @@ public void generateDeserializers(final GenerationContext context) {
                 ""
               );
             final var inputSymbol = context.symbolProvider().toSymbol(input);
+            final String inputType;
+            if (input.hasTrait(PositionalTrait.class)) {
+              // Input type in To native should be unwrapped
+              Shape inputForPositional = context
+                .model()
+                .expectShape(
+                  input
+                    .getAllMembers()
+                    .values()
+                    .stream()
+                    .findFirst()
+                    .get()
+                    .getTarget()
+                );
+              Symbol symbolForPositional = context
+                .symbolProvider()
+                .toSymbol(inputForPositional);
+              inputType =
+                DafnyNameResolver.getDafnyType(
+                  inputForPositional,
+                  symbolForPositional
+                );
+            } else {
+              inputType = DafnyNameResolver.getDafnyType(input, inputSymbol);
+            }
             delegator.useFileWriter(
               "%s/%s".formatted(
                   SmithyNameResolver.shapeNamespace(serviceShape),
@@ -390,7 +444,7 @@ public void generateDeserializers(final GenerationContext context) {
                       ${C|}
                   }""",
                   inputFromDafnyMethodName,
-                  DafnyNameResolver.getDafnyType(input, inputSymbol),
+                  inputType,
                   SmithyNameResolver.getSmithyType(input, inputSymbol),
                   writer.consumer(w ->
                     generateRequestDeserializer(
@@ -408,7 +462,10 @@ public void generateDeserializers(final GenerationContext context) {
         final var output = context
           .model()
           .expectShape(operation.getOutputShape());
-        if (!alreadyVisited.contains(output.toShapeId())) {
+        if (
+          !alreadyVisited.contains(output.toShapeId()) &&
+          !output.hasTrait(PositionalTrait.class)
+        ) {
           alreadyVisited.add(output.toShapeId());
           if (
             !output.hasTrait(UnitTypeTrait.class) &&

codegen/smithy-dafny-codegen/src/main/java/software/amazon/polymorph/smithygo/localservice/shapevisitor/DafnyToSmithyShapeVisitor.java

@@ -13,6 +13,7 @@
 import software.amazon.polymorph.smithygo.localservice.nameresolver.SmithyNameResolver;
 import software.amazon.polymorph.smithygo.utils.GoCodegenUtils;
 import software.amazon.polymorph.traits.DafnyUtf8BytesTrait;
+import software.amazon.polymorph.traits.PositionalTrait;
 import software.amazon.polymorph.traits.ReferenceTrait;
 import software.amazon.smithy.aws.traits.ServiceTrait;
 import software.amazon.smithy.codegen.core.CodegenException;
@@ -276,6 +277,13 @@ public String structureShape(final StructureShape shape) {
       final var targetShape = context
         .model()
         .expectShape(memberShape.getTarget());
+      final String DtorConversion;
+      if (!shape.hasTrait(PositionalTrait.class)) {
+        DtorConversion = ".Dtor_%s()".formatted(memberName);
+      } else {
+        // Shapes with PositionalTrait already gets input unwrapped so no conversion needed.
+        DtorConversion = "";
+      }
       //TODO: Is it ever possible for structure to be nil?
       String maybeAssertion = "";
       if (dataSource.equals("input")) {
@@ -296,7 +304,7 @@ public String structureShape(final StructureShape shape) {
         "%1$s%2$s%3$s%4$s%5$s".formatted(
             dataSource,
             maybeAssertion,
-            ".Dtor_%s()".formatted(memberName),
+            DtorConversion,
             memberShape.isOptional() ? ".UnwrapOr(nil)" : "",
             assertionRequired
               ? ".(%s)".formatted(