Switch to toolchains

Author: fmeum

bazel/private/BUILD

@@ -1,5 +1,4 @@
 load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
-load(":current_protoc.bzl", "current_protoc")
 load(":native_bool_flag.bzl", "native_bool_flag")
 
 package(default_applicable_licenses = ["//:license"])
@@ -29,11 +28,6 @@ toolchain_type(
     visibility = ["//visibility:public"],
 )
 
-current_protoc(
-    name = "current_protoc",
-    visibility = ["//:__subpackages__"],
-)
-
 bzl_library(
     name = "upb_proto_library_internal_bzl",
     srcs = [

protobuf.bzl

@@ -1,8 +1,13 @@
 load("@bazel_skylib//lib:versions.bzl", "versions")
 load("@rules_cc//cc:defs.bzl", "objc_library")
 load("@rules_python//python:defs.bzl", "py_library")
+load("//bazel/common:proto_common.bzl", "proto_common")
 load("//bazel/common:proto_info.bzl", "ProtoInfo")
+<<<<<<< Updated upstream
 load("//bazel/private:current_protoc.bzl", "ProtocFilesToRun")
+=======
+load("//bazel/private:toolchain_helpers.bzl", "toolchains")
+>>>>>>> Stashed changes
 
 def _GetPath(ctx, path):
     if ctx.label.workspace_root:
@@ -72,6 +77,26 @@ def _CsharpOuts(srcs):
         for src in srcs
     ]
 
+_PROTOC_ATTRS = toolchains.if_legacy_toolchain({
+    "_proto_compiler": attr.label(
+        cfg = "exec",
+        executable = True,
+        allow_files = True,
+        default = configuration_field("proto", "proto_compiler"),
+    ),
+})
+_PROTOC_FRAGMENTS = ["proto"]
+_PROTOC_TOOLCHAINS = toolchains.use_toolchain(toolchains.PROTO_TOOLCHAIN)
+
+def _protoc_files_to_run(ctx):
+    if proto_common.INCOMPATIBLE_ENABLE_PROTO_TOOLCHAIN_RESOLUTION:
+        toolchain = ctx.toolchains[toolchains.PROTO_TOOLCHAIN]
+        if not toolchain:
+            fail("Protocol compiler toolchain could not be resolved.")
+        return toolchain.proto.proto_compiler
+    else:
+        return ctx.attr._proto_compiler[DefaultInfo].files_to_run
+
 ProtoGenInfo = provider(
     fields = ["srcs", "import_flags", "deps"],
 )
@@ -311,7 +336,7 @@ def _internal_gen_well_known_protos_java_impl(ctx):
             args.add_all([src.path[offset:] for src in dep.direct_sources])
 
     ctx.actions.run(
-        executable = ctx.attr._protoc[ProtocFilesToRun].files_to_run,
+        executable = _protoc_files_to_run(ctx),
         inputs = descriptors,
         outputs = [srcjar],
         arguments = [args],
@@ -335,10 +360,9 @@ internal_gen_well_known_protos_java = rule(
         "javalite": attr.bool(
             default = False,
         ),
-        "_protoc": attr.label(
-            default = "//bazel/private:current_protoc",
-        ),
-    },
+    } | _PROTOC_ATTRS,
+    fragments = _PROTOC_FRAGMENTS,
+    toolchains = _PROTOC_TOOLCHAINS,
 )
 
 def _internal_gen_kt_protos(ctx):
@@ -372,7 +396,7 @@ def _internal_gen_kt_protos(ctx):
             args.add_all([src.path[offset:] for src in dep.direct_sources])
 
     ctx.actions.run(
-        executable = ctx.attr._protoc[ProtocFilesToRun].files_to_run,
+        executable = _protoc_files_to_run(ctx),
         inputs = descriptors,
         outputs = [srcjar],
         arguments = [args],
@@ -396,10 +420,9 @@ internal_gen_kt_protos = rule(
         "lite": attr.bool(
             default = False,
         ),
-        "_protoc": attr.label(
-            default = "//bazel/private:current_protoc",
-        ),
-    },
+    } | _PROTOC_ATTRS,
+    fragments = _PROTOC_FRAGMENTS,
+    toolchains = _PROTOC_TOOLCHAINS,
 )
 
 def internal_objc_proto_library(