Add local_config_platform repo to WORKSPACE

Part of #6849.

Closes #6933.

PiperOrigin-RevId: 226174300
diff --git a/src/main/java/com/google/devtools/build/lib/BUILD b/src/main/java/com/google/devtools/build/lib/BUILD
index cfeef40..76c28ba 100644
--- a/src/main/java/com/google/devtools/build/lib/BUILD
+++ b/src/main/java/com/google/devtools/build/lib/BUILD
@@ -898,6 +898,9 @@
         ],
         exclude = ["bazel/repository/MavenConnector.java"],
     ),
+    resources = [
+        "bazel/repository/local_config_platform.WORKSPACE",
+    ],
     runtime_deps = [
         "//third_party:jsch",
         "//third_party:maven_model",
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/repository/local_config_platform.WORKSPACE b/src/main/java/com/google/devtools/build/lib/bazel/repository/local_config_platform.WORKSPACE
new file mode 100644
index 0000000..1e6d33f
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/bazel/repository/local_config_platform.WORKSPACE
@@ -0,0 +1 @@
+local_config_platform(name = "local_config_platform")
\ No newline at end of file
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/rules/BazelRuleClassProvider.java b/src/main/java/com/google/devtools/build/lib/bazel/rules/BazelRuleClassProvider.java
index afb58ea..8b23ca2 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/rules/BazelRuleClassProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/rules/BazelRuleClassProvider.java
@@ -386,6 +386,14 @@
           builder.addRuleDefinition(new AndroidSdkRepositoryRule());
           builder.addRuleDefinition(new AndroidNdkRepositoryRule());
           builder.addRuleDefinition(new LocalConfigPlatformRule());
+
+          try {
+            builder.addWorkspaceFilePrefix(
+                ResourceFileLoader.loadResource(
+                    LocalConfigPlatformRule.class, "local_config_platform.WORKSPACE"));
+          } catch (IOException e) {
+            throw new IllegalStateException(e);
+          }
         }
 
         @Override
diff --git a/src/test/shell/bazel/toolchain_test.sh b/src/test/shell/bazel/toolchain_test.sh
index 174506d..3ba917e 100755
--- a/src/test/shell/bazel/toolchain_test.sh
+++ b/src/test/shell/bazel/toolchain_test.sh
@@ -1070,6 +1070,11 @@
   expect_log 'Using toolchain: value "foo"'
 }
 
+function test_local_config_platform() {
+  bazel query @local_config_platform//... &> $TEST_log || fail "Build failed"
+  expect_log '@local_config_platform//:host'
+}
+
 # TODO(katre): Test using toolchain-provided make variables from a genrule.
 
 run_suite "toolchain tests"