Don't default to --release 9 when running on a JDK 9 host_javabase

PiperOrigin-RevId: 195986083
Change-Id: I228f5087929322a888e062282bdf88d625243b22

src/main/java/com/google/devtools/build/lib/bazel/rules/GenericRules.java

diff --git a/src/main/java/com/google/devtools/build/lib/bazel/rules/GenericRules.java b/src/main/java/com/google/devtools/build/lib/bazel/rules/GenericRules.java
index 3bbc32e..8db5c8b6 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/rules/GenericRules.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/rules/GenericRules.java
@@ -53,8 +53,8 @@
               .replace(
                   "%java_toolchain%",
                   isJdk8OrEarlier()
-                      ? "@bazel_tools//tools/jdk:toolchain_jdk8"
-                      : "@bazel_tools//tools/jdk:toolchain_jdk9"));
+                      ? "@bazel_tools//tools/jdk:toolchain_hostjdk8"
+                      : "@bazel_tools//tools/jdk:toolchain_hostjdk9"));
 
     } catch (IOException e) {
       throw new IllegalStateException(e);

tools/jdk/BUILD

diff --git a/tools/jdk/BUILD b/tools/jdk/BUILD
index 92cf7dd..bc7161e 100644
--- a/tools/jdk/BUILD
+++ b/tools/jdk/BUILD
@@ -213,7 +213,7 @@
 )
 
 default_java_toolchain(
-    name = "toolchain_jdk8",
+    name = "toolchain_hostjdk8",
     bootclasspath = [":bootclasspath"],
     extclasspath = [":extclasspath"],
     jvm_opts = JDK8_JVM_OPTS,
@@ -222,7 +222,16 @@
 )
 
 default_java_toolchain(
-    name = "toolchain_jdk9",
+    name = "toolchain_hostjdk9",
+    bootclasspath = [":bootclasspath"],
+    extclasspath = [":extclasspath"],
+    jvm_opts = JDK9_JVM_OPTS,
+    source_version = "8",
+    target_version = "8",
+)
+
+default_java_toolchain(
+    name = "toolchain_java9",
     jvm_opts = JDK9_JVM_OPTS,
     misc = DEFAULT_JAVACOPTS + [
         "--release",