bazel: implement set-gen as a bazel genrule

cmd/libs/go2idl/set-gen/BUILD

@@ -20,3 +20,7 @@ go_binary(
         "//vendor:k8s.io/gengo/examples/set-gen/generators",
     ],
 )
+
+exports_files([
+    "types.go",
+])

hack/boilerplate/BUILD

@@ -0,0 +1,3 @@
+package(default_visibility = ["//visibility:public"])
+
+exports_files(glob(["*.txt"]))

pkg/util/sets/BUILD

@@ -13,14 +13,8 @@ load(
 go_library(
     name = "go_default_library",
     srcs = [
-        "byte.go",
+        ":set-gen",
-        "doc.go",
-        "empty.go",
-        "int.go",
-        "int64.go",
-        "string.go",
     ],
-    tags = ["automanaged"],
 )
 
 go_test(
@@ -30,3 +24,29 @@ go_test(
     tags = ["automanaged"],
     deps = [],
 )
+
+genrule(
+    name = "set-gen",
+    srcs = [
+        "//pkg/util/sets/types:types.go",
+        "//hack/boilerplate:boilerplate.go.txt",
+    ],
+    outs = [
+        "byte.go",
+        "doc.go",
+        "empty.go",
+        "int.go",
+        "int64.go",
+        "string.go",
+    ],
+    cmd = """
+$(location //cmd/libs/go2idl/set-gen) \
+    --input-dirs ./pkg/util/sets/types \
+    --output-base $(GENDIR)/pkg/util \
+    --go-header-file $(location //hack/boilerplate:boilerplate.go.txt) \
+    --output-package sets
+    """,
+    tools = [
+        "//cmd/libs/go2idl/set-gen",
+    ],
+)

pkg/util/sets/types/types.go

@@ -22,7 +22,9 @@ package types
 //go:generate set-gen -i k8s.io/kubernetes/pkg/util/sets/types
 
 type ReferenceSetTypes struct {
-	// These types all cause files to be generated
+	// These types all cause files to be generated.
+	// These types should be reflected in the ouput of
+	// the "//pkg/util/sets:set-gen" genrule.
 	a int64
 	b int
 	c byte