From eda3116879f21c27820eb350c8985f45f078df24 Mon Sep 17 00:00:00 2001
From: John Cater <jcater@google.com>
Date: Tue, 19 Nov 2019 10:50:43 -0500
Subject: [PATCH] Update rust_toolchain to use execution transitions.

---
 rust/toolchain.bzl | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/rust/toolchain.bzl b/rust/toolchain.bzl
index 527923352c..37869bb428 100644
--- a/rust/toolchain.bzl
+++ b/rust/toolchain.bzl
@@ -35,16 +35,20 @@ rust_toolchain = rule(
         "rustc": attr.label(
             doc = "The location of the `rustc` binary. Can be a direct source or a filegroup containing one item.",
             allow_single_file = True,
+            cfg = "exec",
         ),
         "rust_doc": attr.label(
             doc = "The location of the `rustdoc` binary. Can be a direct source or a filegroup containing one item.",
             allow_single_file = True,
+            cfg = "exec",
         ),
         "rustc_lib": attr.label(
             doc = "The libraries used by rustc during compilation.",
+            cfg = "target",
         ),
         "rust_lib": attr.label(
             doc = "The rust standard library.",
+            cfg = "target",
         ),
         "staticlib_ext": attr.string(mandatory = True),
         "dylib_ext": attr.string(mandatory = True),
@@ -57,6 +61,7 @@ rust_toolchain = rule(
         "target_triple": attr.string(),
         "_crosstool": attr.label(
             default = Label("@bazel_tools//tools/cpp:current_cc_toolchain"),
+            cfg = "exec",
         ),
         "opt_level": attr.string_dict(default = {
             "opt": "3",