From d624bcd206e886a11b8d48dc58bf88346a1a776d Mon Sep 17 00:00:00 2001
From: Yun Peng <pcloudy@google.com>
Date: Wed, 10 Nov 2021 16:08:34 +0100
Subject: [PATCH] Propage DEFAULT_SYSTEM_JAVABASE via module extension tag

---
 MODULE.bazel          |  1 +
 java/extensions.bzl   | 14 ++++++++++++--
 java/repositories.bzl |  9 +++++----
 toolchains/BUILD      |  1 +
 4 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/MODULE.bazel b/MODULE.bazel
index 45fd05d5..5025fae4 100644
--- a/MODULE.bazel
+++ b/MODULE.bazel
@@ -29,6 +29,7 @@ bazel_dep(name = "rules_proto", version = "4.0.0")
 bazel_dep(name = "rules_python", version = "0.4.0")
 
 toolchains = use_extension("//java:extensions.bzl", "toolchains")
+toolchains.system_javabase(path=DEFAULT_SYSTEM_JAVABASE)
 
 # Declare remote java tools repos
 use_repo(toolchains, "remote_java_tools")
diff --git a/java/extensions.bzl b/java/extensions.bzl
index fc04283e..468207fd 100644
--- a/java/extensions.bzl
+++ b/java/extensions.bzl
@@ -15,12 +15,22 @@
 
 load("//java:repositories.bzl", "java_tools_javac11_repos", "local_jdk_repo", "remote_jdk11_repos", "remote_jdk15_repos", "remote_jdk16_repos", "remote_jdk17_repos")
 
+system_javabase = tag_class(attrs = {"path": attr.string()})
+
 def _toolchains_impl(ctx):
-    local_jdk_repo()
+    default_system_javabase = None
+    for mod in ctx.modules:
+        if mod.tags.system_javabase:
+            default_system_javabase = mod.tags.system_javabase[0].path
+            break
+    local_jdk_repo(default_system_javabase)
     java_tools_javac11_repos()
     remote_jdk11_repos()
     remote_jdk15_repos()
     remote_jdk16_repos()
     remote_jdk17_repos()
 
-toolchains = module_extension(implementation = _toolchains_impl)
+toolchains = module_extension(
+    implementation = _toolchains_impl,
+    tag_classes = {"system_javabase": system_javabase},
+)
diff --git a/java/repositories.bzl b/java/repositories.bzl
index fdd60277..bdc5326f 100644
--- a/java/repositories.bzl
+++ b/java/repositories.bzl
@@ -65,11 +65,10 @@ def java_tools_javac11_repos():
         ],
     )
 
-def local_jdk_repo():
+def local_jdk_repo(default_system_javabase):
     local_java_repository(
         name = "local_jdk",
-        # TODO:  Need to export DEFAULT_SYSTEM_JAVABASE for module extension environment
-        java_home = DEFAULT_SYSTEM_JAVABASE,
+        java_home = default_system_javabase,
         build_file = Label("//toolchains:jdk.BUILD"),
     )
 
@@ -376,7 +375,9 @@ def rules_java_dependencies():
 
     Loads the remote repositories used by default in Bazel.
     """
-    local_jdk_repo()
+
+    # TODO: pass DEFAULT_SYSTEM_JAVABASE to local_jdk_repo
+    # local_jdk_repo()
     remote_jdk11_repos()
     remote_jdk15_repos()
     remote_jdk16_repos()
diff --git a/toolchains/BUILD b/toolchains/BUILD
index 4f21cbe8..e5f76a8e 100644
--- a/toolchains/BUILD
+++ b/toolchains/BUILD
@@ -6,6 +6,7 @@ load(
     "DEFAULT_TOOLCHAIN_CONFIGURATION",
     "JVM8_TOOLCHAIN_CONFIGURATION",
     "PREBUILT_TOOLCHAIN_CONFIGURATION",
+    "bootclasspath",
     "default_java_toolchain",
     "java_runtime_files",
 )