ScalaPB deps toolchain (bazel-contrib#1104)

* Inject Scalapb deps via providers on the toolchain

* Update scalapb toolchain deps docs

* Lint

* Use external names for default labels

* Add proto toolchain only for deps

`//scala_proto:deps_toolchain_type` is required to uncycle dependency between `//scala_proto:toolchain_type` and generators which depend on the same proto libraries and need to be initialized before the toolchain creation.

* Update toolchain transitions

* Use incompatible_use_toolchain_transition

Author: liucijus

docs/scala_proto_library.md

@@ -34,13 +34,15 @@ To configure ScalaPB options, configure a different `scala_proto_toolchain` and
 
 ```python
 load("@io_bazel_rules_scala//scala_proto:scala_proto_toolchain.bzl", "scala_proto_toolchain")
+load("@io_bazel_rules_scala//scala:providers.bzl", "declare_deps_provider")
 
 scala_proto_toolchain(
     name = "scala_proto_toolchain_configuration",
     with_grpc = False,
     with_flat_package = False,
     with_single_line_to_string = False,
     visibility = ["//visibility:public"],
+    dep_providers = [":my_grpc_deps", ":my_compile_deps"],
 )
 
 toolchain(
@@ -49,6 +51,20 @@ toolchain(
     toolchain_type = "@io_bazel_rules_scala//scala_proto:toolchain_type",
     visibility = ["//visibility:public"],
 )
+
+declare_deps_provider(
+    name = "my_compile_deps",
+    deps_id = "scalapb_compile_deps",
+    deps = ["@dep1", "@dep2"],
+    visibility = ["//visibility:public"],
+)
+
+declare_deps_provider(
+    name = "my_grpc_deps",
+    deps_id = "scalapb_grpc_deps",
+    deps = ["@dep3", "@dep4"],
+    visibility = ["//visibility:public"],
+)
 ```
 
 ### Toolchain Attributes
@@ -63,6 +79,5 @@ toolchain(
 | code_generator                | `Label, optional (has default)` <br> Which code generator to use. A sensible default is provided.
 | named_generators              | `String dict, optional` <br>
 | extra_generator_dependencies  | `List of labels, optional` <br>
-| grpc_deps                     | `List of labels, optional (has default)` <br> gRPC dependencies. A sensible default is provided.
-| implicit_compile_deps         | `List of labels, optional (has default)` <br> ScalaPB dependencies. A sensible default is provided.
 | scalac                        | `Label, optional (has default)` <br> Target for scalac. A sensible default is provided.
+| dep_providers                 | `List of labels, optional (has default)` <br> allows inject gRPC (deps_id - `scalapb_grpc_deps`) and ScalaPB (deps_id `scalapb_compile_deps`) dependencies

scala_proto/BUILD

@@ -1,12 +1,32 @@
 load("@rules_java//java:defs.bzl", "java_library")
-load("//scala_proto:scala_proto_toolchain.bzl", "scala_proto_toolchain")
-load("//scala_proto:default_dep_sets.bzl", "DEFAULT_SCALAPB_COMPILE_DEPS", "DEFAULT_SCALAPB_GRPC_DEPS")
+load(
+    "//scala_proto:scala_proto_toolchain.bzl",
+    "export_scalapb_toolchain_deps",
+    "scala_proto_deps_toolchain",
+    "scala_proto_toolchain",
+)
+load(
+    "//scala_proto:default_dep_sets.bzl",
+    "DEFAULT_SCALAPB_COMPILE_DEPS",
+    "DEFAULT_SCALAPB_GRPC_DEPS",
+)
+load("//scala:providers.bzl", "declare_deps_provider")
 
 toolchain_type(
     name = "toolchain_type",
     visibility = ["//visibility:public"],
 )
 
+toolchain_type(
+    name = "deps_toolchain_type",
+    visibility = ["//visibility:public"],
+)
+
+scala_proto_deps_toolchain(
+    name = "default_deps_toolchain_impl",
+    visibility = ["//visibility:public"],
+)
+
 scala_proto_toolchain(
     name = "default_toolchain_impl",
     visibility = ["//visibility:public"],
@@ -22,6 +42,12 @@ toolchain(
     visibility = ["//visibility:public"],
 )
 
+toolchain(
+    name = "default_deps_toolchain",
+    toolchain = ":default_deps_toolchain_impl",
+    toolchain_type = ":deps_toolchain_type",
+)
+
 scala_proto_toolchain(
     name = "enable_all_options_toolchain_impl",
     visibility = ["//visibility:public"],
@@ -38,14 +64,33 @@ toolchain(
     visibility = ["//visibility:public"],
 )
 
-java_library(
-    name = "default_scalapb_compile_dependencies",
+declare_deps_provider(
+    name = "scalapb_compile_deps_provider",
+    deps_id = "scalapb_compile_deps",
+    visibility = ["//visibility:public"],
+    deps = DEFAULT_SCALAPB_COMPILE_DEPS,
+)
+
+declare_deps_provider(
+    name = "scalapb_grpc_deps_provider",
+    deps_id = "scalapb_grpc_deps",
+    visibility = ["//visibility:public"],
+    deps = DEFAULT_SCALAPB_GRPC_DEPS,
+)
+
+declare_deps_provider(
+    name = "scalapb_worker_deps_provider",
+    deps_id = "scalapb_worker_deps",
     visibility = ["//visibility:public"],
-    exports = DEFAULT_SCALAPB_COMPILE_DEPS,
+    deps = [
+        "//external:io_bazel_rules_scala/dependency/com_google_protobuf/protobuf_java",
+        "//external:io_bazel_rules_scala/dependency/proto/protoc_bridge",
+        "//external:io_bazel_rules_scala/dependency/proto/scalapb_plugin",
+    ],
 )
 
-java_library(
-    name = "default_scalapb_grpc_dependencies",
+export_scalapb_toolchain_deps(
+    name = "scalapb_worker_deps",
+    deps_id = "scalapb_worker_deps",
     visibility = ["//visibility:public"],
-    exports = DEFAULT_SCALAPB_GRPC_DEPS,
 )

scala_proto/private/scala_proto_default_repositories.bzl

@@ -198,3 +198,5 @@ def scala_proto_default_repositories(
         name = "io_bazel_rules_scala/dependency/proto/opencensus_contrib_grpc_metrics",
         actual = "@scala_proto_rules_opencensus_contrib_grpc_metrics//jar",
     )
+
+    native.register_toolchains("@io_bazel_rules_scala//scala_proto:default_deps_toolchain")

scala_proto/private/scalapb_aspect.bzl

@@ -3,6 +3,7 @@ load("//scala/private:common.bzl", "write_manifest_file")
 load("//scala/private:dependency.bzl", "legacy_unclear_dependency_info_for_protobuf_scrooge")
 load("//scala/private:rule_impls.bzl", "compile_scala")
 load("//scala_proto/private:proto_to_scala_src.bzl", "proto_to_scala_src")
+load("//scala/private/toolchain_deps:toolchain_deps.bzl", "find_deps_info_on", "java_info_for_deps")
 
 ScalaPBAspectInfo = provider(fields = [
     "proto_info",
@@ -139,13 +140,23 @@ def _scalapb_aspect_impl(target, ctx):
         compile_protos = sorted(target_ti.direct_sources)
         transitive_protos = sorted(target_ti.transitive_sources.to_list())
 
-        toolchain = ctx.toolchains["@io_bazel_rules_scala//scala_proto:toolchain_type"]
+        deps_toolchain_type_label = "@io_bazel_rules_scala//scala_proto:deps_toolchain_type"
+        toolchain_type_label = "@io_bazel_rules_scala//scala_proto:toolchain_type"
+        toolchain = ctx.toolchains[toolchain_type_label]
         flags = []
-        imps = [j[JavaInfo] for j in ctx.attr._implicit_compile_deps]
+
+        compile_deps = find_deps_info_on(
+            ctx,
+            deps_toolchain_type_label,
+            "scalapb_compile_deps",
+        ).deps
+
+        imps = [dep[JavaInfo] for dep in compile_deps]
 
         if toolchain.with_grpc:
+            grpc_deps = find_deps_info_on(ctx, deps_toolchain_type_label, "scalapb_grpc_deps").deps
             flags.append("grpc")
-            imps.extend([j[JavaInfo] for j in ctx.attr._grpc_deps])
+            imps.extend([dep[JavaInfo] for dep in grpc_deps])
 
         if toolchain.with_flat_package:
             flags.append("flat_package")
@@ -233,16 +244,16 @@ scalapb_aspect = aspect(
         [ScalaPBImport],
     ],
     attrs = {
-        "_protoc": attr.label(executable = True, cfg = "host", default = "@com_google_protobuf//:protoc"),
-        "_implicit_compile_deps": attr.label_list(cfg = "target", default = [
-            "//external:io_bazel_rules_scala/dependency/proto/implicit_compile_deps",
-        ]),
-        "_grpc_deps": attr.label_list(cfg = "target", default = [
-            "//external:io_bazel_rules_scala/dependency/proto/grpc_deps",
-        ]),
+        "_protoc": attr.label(
+            executable = True,
+            cfg = "exec",
+            default = "@com_google_protobuf//:protoc",
+        ),
     },
+    incompatible_use_toolchain_transition = True,
     toolchains = [
         "@io_bazel_rules_scala//scala:toolchain_type",
         "@io_bazel_rules_scala//scala_proto:toolchain_type",
+        "@io_bazel_rules_scala//scala_proto:deps_toolchain_type",
     ],
 )

scala_proto/scala_proto_toolchain.bzl

@@ -1,4 +1,6 @@
 load("//scala_proto:default_dep_sets.bzl", "DEFAULT_SCALAPB_COMPILE_DEPS", "DEFAULT_SCALAPB_GRPC_DEPS")
+load("@io_bazel_rules_scala//scala:providers.bzl", "DepsInfo")
+load("//scala/private/toolchain_deps:toolchain_deps.bzl", "expose_toolchain_deps")
 
 def _scala_proto_toolchain_impl(ctx):
     toolchain = platform_common.ToolchainInfo(
@@ -28,7 +30,7 @@ scala_proto_toolchain = rule(
         "blacklisted_protos": attr.label_list(default = []),
         "code_generator": attr.label(
             executable = True,
-            cfg = "host",
+            cfg = "exec",
             default = Label("@io_bazel_rules_scala//src/scala/scripts:scalapb_worker"),
             allow_files = True,
         ),
@@ -43,3 +45,38 @@ scala_proto_toolchain = rule(
         ),
     },
 )
+
+def _scala_proto_deps_toolchain(ctx):
+    toolchain = platform_common.ToolchainInfo(
+        dep_providers = ctx.attr.dep_providers,
+    )
+    return [toolchain]
+
+scala_proto_deps_toolchain = rule(
+    _scala_proto_deps_toolchain,
+    attrs = {
+        "dep_providers": attr.label_list(
+            default = [
+                "@io_bazel_rules_scala//scala_proto:scalapb_compile_deps_provider",
+                "@io_bazel_rules_scala//scala_proto:scalapb_grpc_deps_provider",
+                "@io_bazel_rules_scala//scala_proto:scalapb_worker_deps_provider",
+            ],
+            cfg = "target",
+            providers = [DepsInfo],
+        ),
+    },
+)
+
+def _export_scalapb_toolchain_deps(ctx):
+    return expose_toolchain_deps(ctx, "@io_bazel_rules_scala//scala_proto:deps_toolchain_type")
+
+export_scalapb_toolchain_deps = rule(
+    _export_scalapb_toolchain_deps,
+    attrs = {
+        "deps_id": attr.string(
+            mandatory = True,
+        ),
+    },
+    incompatible_use_toolchain_transition = True,
+    toolchains = ["@io_bazel_rules_scala//scala_proto:deps_toolchain_type"],
+)

src/scala/scripts/BUILD

@@ -31,18 +31,10 @@ scala_library(
 scala_library(
     name = "scalapb_worker_lib",
     srcs = ["ScalaPBWorker.scala"],
-    unused_dependency_checker_ignored_targets = [
-        "//external:io_bazel_rules_scala/dependency/com_google_protobuf/protobuf_java",
-    ],
     visibility = ["//visibility:public"],
-    runtime_deps = [
-        "//external:io_bazel_rules_scala/dependency/com_google_protobuf/protobuf_java",
-    ],
     deps = [
         ":scala_proto_request_extractor",
-        "//external:io_bazel_rules_scala/dependency/com_google_protobuf/protobuf_java",
-        "//external:io_bazel_rules_scala/dependency/proto/protoc_bridge",
-        "//external:io_bazel_rules_scala/dependency/proto/scalapb_plugin",
+        "//scala_proto:scalapb_worker_deps",
         "//src/java/io/bazel/rulesscala/io_utils",
         "//src/java/io/bazel/rulesscala/jar",
         "//src/java/io/bazel/rulesscala/worker",

test/src/main/scala/scalarules/test/extra_protobuf_generator/BUILD

@@ -5,8 +5,6 @@ scala_library(
     srcs = ["ExtraProtobufGenerator.scala"],
     visibility = ["//visibility:public"],
     deps = [
-        "//external:io_bazel_rules_scala/dependency/com_google_protobuf/protobuf_java",
-        "//external:io_bazel_rules_scala/dependency/proto/protoc_bridge",
-        "//external:io_bazel_rules_scala/dependency/proto/scalapb_plugin",
+        "//scala_proto:scalapb_worker_deps",
     ],
 )