minimal Scala codegen interface support (#13858)

* add inherited choices for Scala codegen, test output exercises

CHANGELOG_BEGIN
- [scala codegen] Choices inherited from interfaces may be exercised
  directly from those templates via ``createAnd``, contract ID, or
  exercise-by-key.  Exercise by interface-contract-ID and
  interface-contract-ID types in signatures are not supported.
  See `issue #13858 <https://github.com/digital-asset/daml/pull/13858>`__.
CHANGELOG_END

language-support/scala/codegen-sample-app/BUILD.bazel

@@ -17,16 +17,19 @@ load(
     "lf_version_configuration",
 )
 
+# TODO(#13296) change to "latest" when interfaces released
+tested_lf_config = "dev"
+
 daml_compile(
     name = "MyMain",
     srcs = ["src/main/daml/MyMain.daml"],
-    target = lf_version_configuration.get("latest"),
+    target = lf_version_configuration.get(tested_lf_config),
 )
 
 daml_compile(
     name = "MySecondMain",
     srcs = ["src/main/daml/MySecondMain.daml"],
-    target = lf_version_configuration.get("latest"),
+    target = lf_version_configuration.get(tested_lf_config),
 )
 
 dar_to_scala(
@@ -34,7 +37,7 @@ dar_to_scala(
     srcs = [
         ":MyMain.dar",
         ":MySecondMain.dar",
-        "//daml-lf/encoder:testing-dar-latest",
+        "//daml-lf/encoder:testing-dar-%s" % tested_lf_config,
     ],
     package_prefix = "com.daml.sample",
     srcjar_out = "MyMain.srcjar",

language-support/scala/codegen-sample-app/src/main/daml/MyMain.daml

@@ -590,3 +590,24 @@ template JustMapUser
        aMap: JustMap Int Int
     where
       signatory party
+
+interface InterfaceToMix where
+  getOwner: Party
+  choice InheritedOnly: () with
+    controller getOwner this
+    do return ()
+{- TODO(#13349) uncomment when overloaded choices compile
+  choice OverloadedInTemplate: () with
+    controller getOwner this
+    do return ()
+-}
+
+template InterfaceMixer with
+    party: Party
+  where
+    signatory party
+    choice OverloadedInTemplate: () with
+      controller party
+      do return ()
+    implements InterfaceToMix where
+      getOwner = party

language-support/scala/codegen-sample-app/src/test/scala/com/digitalasset/codegen/GeneratedCommandsUT.scala

@@ -3,7 +3,9 @@
 
 package com.daml.codegen
 
-import com.daml.sample.MyMain.{Increment, KeyedNumber, SimpleListExample}
+import com.daml.sample.MyMain
+import MyMain.{KeyedNumber, Increment, SimpleListExample}
+import com.daml.ledger.api.refinements.ApiTypes
 import com.daml.ledger.api.v1.{commands => rpccmd}
 import com.daml.ledger.client.binding.{Primitive => P}
 
@@ -33,6 +35,42 @@ class GeneratedCommandsUT extends AnyWordSpec with Matchers with Inside {
     }
   }
 
+  "exercise" should {
+    import com.daml.ledger.client.binding.Value.encode
+    val imId: P.ContractId[MyMain.InterfaceMixer] = P.ContractId("fakeimid")
+    val DirectTemplateId = ApiTypes.TemplateId unwrap MyMain.InterfaceMixer.id
+
+    "invoke directly-defined choices" in {
+      inside(imId.exerciseOverloadedInTemplate(alice).command.command) {
+        case rpccmd.Command.Command.Exercise(
+              rpccmd.ExerciseCommand(
+                Some(DirectTemplateId),
+                cid,
+                "OverloadedInTemplate",
+                Some(choiceArg),
+              )
+            ) =>
+          cid should ===(imId)
+          choiceArg should ===(encode(MyMain.OverloadedInTemplate()))
+      }
+    }
+
+    "invoke interface-inherited choices, directly from template" in {
+      inside(imId.exerciseInheritedOnly(alice).command.command) {
+        case rpccmd.Command.Command.Exercise(
+              rpccmd.ExerciseCommand(
+                Some(DirectTemplateId), // TODO(#13349, #13668) must be interface ID
+                cid,
+                "InheritedOnly",
+                Some(choiceArg),
+              )
+            ) =>
+          cid should ===(imId)
+          choiceArg should ===(encode(MyMain.InheritedOnly()))
+      }
+    }
+  }
+
   "key" should {
     "make an exercise-by-key command" in {
       inside((KeyedNumber.key(alice).exerciseIncrement(alice, 42)).command.command) {

language-support/scala/codegen/src/main/scala/com/digitalasset/lf/codegen/CodeGen.scala

@@ -74,7 +74,7 @@ object CodeGen {
       roots: Seq[String],
   ): ValidationNel[String, Unit] =
     decodeInterfaces(files).map { interfaces: NonEmptyList[EnvironmentInterface] =>
-      val combined = interfaces.suml1
+      val combined = interfaces.suml1.resolveChoices
       val interface = combined.copy(
         typeDecls = Util.filterTemplatesBy(roots.map(_.r))(combined.typeDecls)
       )
@@ -134,7 +134,7 @@ object CodeGen {
     val typeDeclarationsToGenerate =
       DependencyGraph.transitiveClosure(
         serializableTypes = util.iface.typeDecls,
-        interfaces = Map.empty, // TODO(#13349)
+        interfaces = util.iface.astInterfaces,
       )
 
     // Each record/variant has Scala code generated for it individually, unless their names are related
@@ -164,6 +164,7 @@ object CodeGen {
     // 1. collect records, search variants and splat/filter
     val (unassociatedRecords, splattedVariants, enums) = splatVariants(definitions)
 
+    // TODO(#13349) include interfaces as well
     // 2. put templates/types into single Namespace.fromHierarchy
     val treeified: Namespace[String, Option[lf.HierarchicalOutput.TemplateOrDatatype]] =
       Namespace.fromHierarchy {