Clean up Java toolchain configuration

now that JDK 8 host_javabases are no longer supported.

PiperOrigin-RevId: 207687089

Author: cushon

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

@@ -46,16 +46,7 @@ public void init(ConfiguredRuleClassProvider.Builder builder) {
 
     try {
       builder.addWorkspaceFilePrefix(
-          ResourceFileLoader.loadResource(BazelRuleClassProvider.class, "tools.WORKSPACE")
-              // Hackily select the java_toolchain based on the host JDK version. JDK 8 and
-              // 9 host_javabases require different toolchains, e.g. to use --patch-module
-              // instead of -Xbootclasspath/p:.
-              .replace(
-                  "%java_toolchain%",
-                  isJdk8OrEarlier()
-                      ? "@bazel_tools//tools/jdk:toolchain_hostjdk8"
-                      : "@bazel_tools//tools/jdk:toolchain_hostjdk10"));
-
+          ResourceFileLoader.loadResource(BazelRuleClassProvider.class, "tools.WORKSPACE"));
     } catch (IOException e) {
       throw new IllegalStateException(e);
     }
@@ -65,8 +56,4 @@ public void init(ConfiguredRuleClassProvider.Builder builder) {
   public ImmutableList<RuleSet> requires() {
     return ImmutableList.of(CoreRules.INSTANCE);
   }
-
-  private static boolean isJdk8OrEarlier() {
-    return Double.parseDouble(System.getProperty("java.class.version")) <= 52.0;
-  }
 }

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

@@ -1,3 +1,2 @@
 local_repository(name = "bazel_tools", path = __embedded_dir__ + "/embedded_tools")
 bind(name = "cc_toolchain", actual = "@bazel_tools//tools/cpp:default-toolchain")
-bind(name = "java_toolchain", actual = "%java_toolchain%")

tools/jdk/BUILD

@@ -3,8 +3,6 @@ package(default_visibility = ["//visibility:public"])
 load(
     "//tools/jdk:default_java_toolchain.bzl",
     "default_java_toolchain",
-    "JDK8_JVM_OPTS",
-    "JDK10_JVM_OPTS",
     "DEFAULT_JAVACOPTS",
 )
 
@@ -195,27 +193,15 @@ genrule(
 )
 
 default_java_toolchain(
-    name = "toolchain_hostjdk8",
-    bootclasspath = [":bootclasspath"],
-    extclasspath = [":extclasspath"],
-    jvm_opts = JDK8_JVM_OPTS,
-    source_version = "8",
-    target_version = "8",
-)
-
-default_java_toolchain(
-    name = "toolchain_hostjdk10",
+    name = "toolchain",
     bootclasspath = [":bootclasspath"],
     extclasspath = [":extclasspath"],
-    jvm_opts = JDK10_JVM_OPTS,
     source_version = "8",
     target_version = "8",
 )
 
 default_java_toolchain(
     name = "toolchain_java9",
-    # We use the same flags for JDK9 and 10
-    jvm_opts = JDK10_JVM_OPTS,
     misc = DEFAULT_JAVACOPTS + [
         "--release",
         "9",
@@ -224,18 +210,12 @@ default_java_toolchain(
 
 default_java_toolchain(
     name = "toolchain_java10",
-    jvm_opts = JDK10_JVM_OPTS,
     misc = DEFAULT_JAVACOPTS + [
         "--release",
         "10",
     ],
 )
 
-alias(
-    name = "toolchain",
-    actual = "//external:java_toolchain",
-)
-
 filegroup(
     name = "srcs",
     srcs = [

tools/jdk/default_java_toolchain.bzl

@@ -14,11 +14,7 @@
 
 """Bazel rules for creating Java toolchains."""
 
-JDK8_JVM_OPTS = [
-    "-Xbootclasspath/p:$(location @bazel_tools//third_party/java/jdk/langtools:javac_jar)",
-]
-
-JDK10_JVM_OPTS = [
+JVM_OPTS = [
     # In JDK9 we have seen a ~30% slow down in JavaBuilder performance when using
     # G1 collector and having compact strings enabled.
     "-XX:+UseParallelOldGC",
@@ -75,7 +71,7 @@ DEFAULT_TOOLCHAIN_CONFIGURATION = {
         "@bazel_tools//third_party/java/jdk/langtools:jdk_compiler_jar",
     ],
     "javac_supports_workers": 1,
-    "jvm_opts": JDK8_JVM_OPTS,
+    "jvm_opts": JVM_OPTS,
     "misc": DEFAULT_JAVACOPTS,
     "compatible_javacopts": COMPATIBLE_JAVACOPTS,
     "singlejar": ["@bazel_tools//tools/jdk:singlejar"],