Add a new toolchain type for c++. In order to do this, PlatformConfiguration is made a legal configuration fragment for every rule class.

Add a default "dummy" c++ toolchain to prevent resolution errors when legacy toolchain selection logic is used.  Add toolchain mocks to java and shell tests.

PiperOrigin-RevId: 167901210

5 files changed, 70 insertions, 0 deletions

diff --git a/tools/cpp/BUILD b/tools/cpp/BUILD
index 1a4dc674ea..eb75333e75 100644
--- a/tools/cpp/BUILD
+++ b/tools/cpp/BUILD
@@ -204,3 +204,18 @@ filegroup(
     name = "link_dynamic_library",
     srcs = ["link_dynamic_library.sh"],
 )
+
+toolchain_type(name = "toolchain_type")
+
+# A dummy toolchain is necessary to satisfy toolchain resolution until platforms
+# are used in c++ by default.
+# TODO(b/64754003): Remove once platforms are used in c++ by default.
+toolchain(
+    name = "dummy_cc_toolchain",
+    toolchain = "dummy_cc_toolchain_impl",
+    toolchain_type = ":toolchain_type",
+)
+
+load(":dummy_toolchain.bzl", "dummy_toolchain")
+
+dummy_toolchain(name = "dummy_cc_toolchain_impl")
diff --git a/tools/cpp/BUILD.static b/tools/cpp/BUILD.static
index 9ae4950d80..aaadc5bad8 100644
--- a/tools/cpp/BUILD.static
+++ b/tools/cpp/BUILD.static
@@ -115,3 +115,18 @@ filegroup(
     name = "link_dynamic_library",
     srcs = ["link_dynamic_library.sh"],
 )
+
+toolchain_type(name = "toolchain_type")
+
+# A dummy toolchain is necessary to satisfy toolchain resolution until platforms
+# are used in c++ by default.
+# TODO(b/64754003): Remove once platforms are used in c++ by default.
+toolchain(
+    name = "dummy_cc_toolchain",
+    toolchain = "dummy_cc_toolchain_impl",
+    toolchain_type = ":toolchain_type",
+)
+
+load(":dummy_toolchain.bzl", "dummy_toolchain")
+
+dummy_toolchain(name = "dummy_cc_toolchain_impl")
diff --git a/tools/cpp/BUILD.tpl b/tools/cpp/BUILD.tpl
index 5ea5368c62..170fe3f91d 100644
--- a/tools/cpp/BUILD.tpl
+++ b/tools/cpp/BUILD.tpl
@@ -75,3 +75,18 @@ cc_toolchain(
     strip_files = ":empty",
     supports_param_files = 1,
 )
+
+toolchain_type(name = "toolchain_type")
+
+# A dummy toolchain is necessary to satisfy toolchain resolution until platforms
+# are used in c++ by default.
+# TODO(b/64754003): Remove once platforms are used in c++ by default.
+toolchain(
+    name = "dummy_cc_toolchain",
+    toolchain = "dummy_cc_toolchain_impl",
+    toolchain_type = ":toolchain_type",
+)
+
+load(":dummy_toolchain.bzl", "dummy_toolchain")
+
+dummy_toolchain(name = "dummy_cc_toolchain_impl")
diff --git a/tools/cpp/cc_configure.bzl b/tools/cpp/cc_configure.bzl
index 70e2fd0ff1..9d6d29fc82 100644
--- a/tools/cpp/cc_configure.bzl
+++ b/tools/cpp/cc_configure.bzl
@@ -20,6 +20,8 @@ load("@bazel_tools//tools/cpp:unix_cc_configure.bzl", "configure_unix_toolchain"
 load("@bazel_tools//tools/cpp:lib_cc_configure.bzl", "get_cpu_value")
 
 def _impl(repository_ctx):
+  repository_ctx.symlink(
+      Label("@bazel_tools//tools/cpp:dummy_toolchain.bzl"), "dummy_toolchain.bzl")
   cpu_value = get_cpu_value(repository_ctx)
   if cpu_value == "freebsd":
     # This is defaulting to the static crosstool, we should eventually
diff --git a/tools/cpp/dummy_toolchain.bzl b/tools/cpp/dummy_toolchain.bzl
new file mode 100644
index 0000000000..c787f7315d
--- /dev/null
+++ b/tools/cpp/dummy_toolchain.bzl
@@ -0,0 +1,23 @@
+# pylint: disable=g-bad-file-header
+# Copyright 2017 The Bazel Authors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Skylark rule that stubs a toolchain."""
+def _dummy_toolchain_impl(ctx):
+  ctx = ctx  # unused argument
+  toolchain = platform_common.ToolchainInfo()
+  return [toolchain]
+
+dummy_toolchain = rule(_dummy_toolchain_impl, attrs = {})
+