add scala protobuf example

3rdparty/jvm/com/thesamet/scalapb/BUILD

@@ -0,0 +1,6 @@
+jvm_artifact(
+  name="scalapb-runtime_2.13",
+  group="com.thesamet.scalapb",
+  artifact="scalapb-runtime_2.13",
+  version="0.11.6",
+)

3rdparty/jvm/default.lock

@@ -0,0 +1,157 @@
+# This lockfile was autogenerated by Pants. To regenerate, run:
+#
+#    ./pants generate-lockfiles
+#
+# --- BEGIN PANTS LOCKFILE METADATA: DO NOT EDIT OR REMOVE ---
+# {
+#   "version": 1,
+#   "generated_with_requirements": [
+#     "com.thesamet.scalapb:scalapb-runtime_2.13:0.11.6,url=not_provided,jar=not_provided",
+#     "org.scala-lang:scala-library:2.13.8,url=not_provided,jar=not_provided"
+#   ]
+# }
+# --- END PANTS LOCKFILE METADATA ---
+
+[[entries]]
+directDependencies = []
+dependencies = []
+file_name = "com.google.protobuf_protobuf-java_3.15.8.jar"
+
+[entries.coord]
+group = "com.google.protobuf"
+artifact = "protobuf-java"
+version = "3.15.8"
+packaging = "jar"
+[entries.file_digest]
+fingerprint = "8d0e2f9834f4fc1a083a65239adc507ca83682c754a27f4c80e4f21990eff686"
+serialized_bytes_length = 1674945
+[[entries]]
+file_name = "com.thesamet.scalapb_lenses_2.13_0.11.6.jar"
+[[entries.directDependencies]]
+group = "org.scala-lang"
+artifact = "scala-library"
+version = "2.13.8"
+packaging = "jar"
+
+[[entries.directDependencies]]
+group = "org.scala-lang.modules"
+artifact = "scala-collection-compat_2.13"
+version = "2.5.0"
+packaging = "jar"
+
+[[entries.dependencies]]
+group = "org.scala-lang"
+artifact = "scala-library"
+version = "2.13.8"
+packaging = "jar"
+
+[[entries.dependencies]]
+group = "org.scala-lang.modules"
+artifact = "scala-collection-compat_2.13"
+version = "2.5.0"
+packaging = "jar"
+
+
+[entries.coord]
+group = "com.thesamet.scalapb"
+artifact = "lenses_2.13"
+version = "0.11.6"
+packaging = "jar"
+[entries.file_digest]
+fingerprint = "d1882eebf6deb4b1bb85c3c188790b28985214ac0dcfd79617fd04cc2e6df2de"
+serialized_bytes_length = 34801
+[[entries]]
+file_name = "com.thesamet.scalapb_scalapb-runtime_2.13_0.11.6.jar"
+[[entries.directDependencies]]
+group = "com.google.protobuf"
+artifact = "protobuf-java"
+version = "3.15.8"
+packaging = "jar"
+
+[[entries.directDependencies]]
+group = "com.thesamet.scalapb"
+artifact = "lenses_2.13"
+version = "0.11.6"
+packaging = "jar"
+
+[[entries.directDependencies]]
+group = "org.scala-lang"
+artifact = "scala-library"
+version = "2.13.8"
+packaging = "jar"
+
+[[entries.directDependencies]]
+group = "org.scala-lang.modules"
+artifact = "scala-collection-compat_2.13"
+version = "2.5.0"
+packaging = "jar"
+
+[[entries.dependencies]]
+group = "com.google.protobuf"
+artifact = "protobuf-java"
+version = "3.15.8"
+packaging = "jar"
+
+[[entries.dependencies]]
+group = "com.thesamet.scalapb"
+artifact = "lenses_2.13"
+version = "0.11.6"
+packaging = "jar"
+
+[[entries.dependencies]]
+group = "org.scala-lang"
+artifact = "scala-library"
+version = "2.13.8"
+packaging = "jar"
+
+[[entries.dependencies]]
+group = "org.scala-lang.modules"
+artifact = "scala-collection-compat_2.13"
+version = "2.5.0"
+packaging = "jar"
+
+
+[entries.coord]
+group = "com.thesamet.scalapb"
+artifact = "scalapb-runtime_2.13"
+version = "0.11.6"
+packaging = "jar"
+[entries.file_digest]
+fingerprint = "439b613f40b9ac43db4d68de5bef36befc56393d9c9cd002e2b965ce94f6f793"
+serialized_bytes_length = 2426575
+[[entries]]
+file_name = "org.scala-lang.modules_scala-collection-compat_2.13_2.5.0.jar"
+[[entries.directDependencies]]
+group = "org.scala-lang"
+artifact = "scala-library"
+version = "2.13.8"
+packaging = "jar"
+
+[[entries.dependencies]]
+group = "org.scala-lang"
+artifact = "scala-library"
+version = "2.13.8"
+packaging = "jar"
+
+
+[entries.coord]
+group = "org.scala-lang.modules"
+artifact = "scala-collection-compat_2.13"
+version = "2.5.0"
+packaging = "jar"
+[entries.file_digest]
+fingerprint = "93f8bf202ac28c4ca13562e31f6881a7770768e12b056b568139f37c025a3841"
+serialized_bytes_length = 5610
+[[entries]]
+directDependencies = []
+dependencies = []
+file_name = "org.scala-lang_scala-library_2.13.8.jar"
+
+[entries.coord]
+group = "org.scala-lang"
+artifact = "scala-library"
+version = "2.13.8"
+packaging = "jar"
+[entries.file_digest]
+fingerprint = "a0882b82514190c2bac7d1a459872a75f005fc0f3e88b2bc0390367146e35db7"
+serialized_bytes_length = 6003601

3rdparty/jvm/org/scala-lang/BUILD

@@ -0,0 +1,6 @@
+jvm_artifact(
+  name="org.scala-lang_scala-library_2.13.8",
+  group="org.scala-lang",
+  artifact="scala-library",
+  version="2.13.8"
+)

pants.toml

@@ -1,16 +1,16 @@
 [GLOBAL]
-pants_version = "2.10.0"
+pants_version = "2.11.0rc0"
 backend_packages = [
-  "pants.backend.codegen.protobuf.python",
+  # TODO: There is a conflict between the runtime dependencies for Python and Scala:
+  #   see https://github.com/pantsbuild/pants/issues/14694#issuecomment-1083565675
+  #"pants.backend.codegen.protobuf.python",
   "pants.backend.codegen.thrift.apache.python",
+  "pants.backend.experimental.codegen.protobuf.scala",
+  "pants.backend.experimental.java",
+  "pants.backend.experimental.scala",
   "pants.backend.python",
 ]
 
-# This will become the default in 2.11, and is only explicitly set to not break
-# backwards-compatibility for existing users. If you are setting up Pants for
-# the first time, set this to false.
-use_deprecated_python_macros = false
-
 [anonymous-telemetry]
 enabled = true
 repo_id = "205E301D-44A4-42FF-8495-C9D41871A431"
@@ -23,3 +23,13 @@ interpreter_constraints = ["CPython>=3.8,<3.11"]
  # `generate-lockfiles` goal for Pants to generate the lockfile for you, although in some
  # situations you may need to manually generate it, as explained in the docs.
 enable_resolves = true
+
+[scala.version_for_resolve]
+"jvm-default" = "2.13.8"
+
+[scalapb]
+# In Pants `2.11.x`, the runtime dependency of `scalapb` targets must be explicitly specified. But
+# in `2.12.x`, it is inferred via #14898 based on its presence in the relevant thirdparty resolve.
+runtime_dependencies = [
+  '3rdparty/jvm/com/thesamet/scalapb:scalapb-runtime_2.13'
+]

src/jvm/org/pantsbuild/example/codegen/scala/BUILD

@@ -0,0 +1,4 @@
+# NB: Dependency inference is not yet implemented for JVM targets depending on protobuf targets,
+# and so this dependency must be specified explicitly.
+#  see https://github.com/pantsbuild/pants/issues/14960
+scala_sources(dependencies=["src/protobuf/simple_example"])

src/jvm/org/pantsbuild/example/codegen/scala/PersonSample.scala

@@ -0,0 +1,15 @@
+package org.pantsbuild.example.codegen.scala
+
+import org.pantsbuild.example.codegen.protos.person.Person
+
+object PersonSample {
+  def main(args: Array[String]): Unit = {
+    val p = Person(
+      name = "Someone",
+      id = 1234,
+      email = "someone@example.com",
+    )
+    println(p)
+  }
+}
+

src/protobuf/simple_example/BUILD

@@ -2,5 +2,5 @@ protobuf_sources(
     # This will generate files under `src/python`, rather than `src/protobuf`, which is convenient
     # so that we do not need to add `__init__.py` files to `src/protobuf`. See
     # https://www.pantsbuild.org/docs/protobuf-python#protobuf-and-source-roots
-    python_source_root="src/python",
+    #python_source_root="src/python",
 )

src/protobuf/simple_example/person.proto

@@ -2,6 +2,8 @@ syntax = "proto3";
 
 package simple_example;
 
+option java_package = "org.pantsbuild.example.codegen.protos";
+
 message Person {
   string name = 1;
   int32 id = 2;