feat: introduce toolchain helper

4 files changed, 59 insertions, 0 deletions

diff --git a/WORKSPACE b/WORKSPACE
index ff6744f..2751746 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -11,6 +11,10 @@ load(":dev_deps.bzl", "rules_proto_dev_deps")
 
 rules_proto_dev_deps()
 
+load("@bazel_skylib//:workspace.bzl", "bazel_skylib_workspace")
+
+bazel_skylib_workspace()
+
 load("@com_google_protobuf//:protobuf_deps.bzl", "protobuf_deps")
 
 protobuf_deps()
diff --git a/proto/proto_common.bzl b/proto/proto_common.bzl
index 6184971..26347a8 100644
--- a/proto/proto_common.bzl
+++ b/proto/proto_common.bzl
@@ -22,3 +22,33 @@ load("//proto/private:native.bzl", "native_proto_common")
 proto_common = native_proto_common
 
 ProtoLangToolchainInfo = proto_common.ProtoLangToolchainInfo
+
+def _incompatible_toolchains_enabled():
+    getattr(proto_common, "INCOMPATIBLE_ENABLE_PROTO_TOOLCHAIN_RESOLUTION", False)
+
+def _find_toolchain(ctx, legacy_attr, toolchain_type):
+    if _incompatible_toolchains_enabled():
+        toolchain = ctx.toolchains[toolchain_type]
+        if not toolchain:
+            fail("No toolchains registered for '%s'." % toolchain_type)
+        return toolchain.proto
+    else:
+        return getattr(ctx.attr, legacy_attr)[ProtoLangToolchainInfo]
+
+def _use_toolchain(toolchain_type):
+    if _incompatible_toolchains_enabled():
+        return [config_common.toolchain_type(toolchain_type, mandatory = False)]
+    else:
+        return []
+
+def _if_legacy_toolchain(legacy_attr_dict):
+    if _incompatible_toolchains_enabled():
+        return {}
+    else:
+        return legacy_attr_dict
+
+toolchains = struct(
+    use_toolchain = _use_toolchain,
+    find_toolchain = _find_toolchain,
+    if_legacy_toolchain = _if_legacy_toolchain,
+)
\ No newline at end of file
diff --git a/tests/proto_common/BUILD.bazel b/tests/proto_common/BUILD.bazel
new file mode 100644
index 0000000..4625e52
--- /dev/null
+++ b/tests/proto_common/BUILD.bazel
@@ -0,0 +1,4 @@
+load(":toolchains.bzl", "unittest_toolchains")
+
+unittest_toolchains()
+
diff --git a/tests/proto_common/toolchains.bzl b/tests/proto_common/toolchains.bzl
new file mode 100644
index 0000000..3a639af
--- /dev/null
+++ b/tests/proto_common/toolchains.bzl
@@ -0,0 +1,21 @@
+load("@bazel_skylib//lib:unittest.bzl", "asserts", "unittest")
+load("//proto:proto_common.bzl", "toolchains")
+
+def _test_toolchains(ctx):
+    env = unittest.begin(ctx)
+
+    asserts.equals(env, {}, toolchains.if_legacy_toolchain({}))
+    asserts.equals(env, None, toolchains.if_legacy_toolchain(None))
+    asserts.equals(env, False, toolchains.if_legacy_toolchain(False))
+    asserts.equals(env, False, toolchains.if_legacy_toolchain(False))
+
+    return unittest.end(env)
+
+toolchains_test = unittest.make(_test_toolchains)
+
+# buildifier: disable=unnamed-macro
+def unittest_toolchains():
+    unittest.suite(
+        "test_toolchains",
+        toolchains_test
+    )