WIP: License lookup - a better version

WORKSPACE

@@ -16,6 +16,14 @@ http_file(
     urls = [COURSIER_CLI_GITHUB_ASSET_URL],
 )
 
+http_archive(
+    name = "rules_license",
+    urls = [
+        "https://mirror.bazel.build/github.com/bazelbuild/rules_license/releases/download/0.0.1/rules_license-0.0.1.tar.gz",
+    ],
+    sha256 = "4865059254da674e3d18ab242e21c17f7e3e8c6b1f1421fffa4c5070f82e98b5",
+)
+
 # Begin Skylib dependencies
 
 http_archive(

license_classifier.bzl

@@ -0,0 +1,7 @@
+# lookup_license: Returns the license information for a maven it.
+# The dependency parser calls this while generating the @maven/BUILD file.
+# This is a no-op fallback, that will be overwritten by the patch command
+# use_license_classifier.sh.
+
+def lookup_license(url=None, sha256=None, maven_id=None):
+    return None

license_demo/BUILD

@@ -0,0 +1,9 @@
+
+
+java_library(
+    name = "my_lib",
+    srcs = ["MyLib.java"],
+    deps = [
+        "@maven//:junit_junit",
+    ],
+)

license_demo/MyLib.java

@@ -0,0 +1,10 @@
+/**
+ * 
+ */
+final class MyLib {
+
+  public MyLib() {
+  }
+
+  int foo() { return 1; }
+}

license_demo/WORKSPACE

@@ -0,0 +1,60 @@
+# Copyright 2022 The Bazel Authors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+workspace(name = "demo")
+
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+
+http_archive(
+    name = "rules_license",
+    urls = [
+        "https://mirror.bazel.build/github.com/bazelbuild/rules_license/releases/download/0.0.1/rules_license-0.0.1.tar.gz",
+    ],
+    sha256 = "4865059254da674e3d18ab242e21c17f7e3e8c6b1f1421fffa4c5070f82e98b5",
+)
+
+# You must expose your own license declarations as a repository so the rules
+# generated in @maven can point to them. Otherwise you would have to generate
+# the declarations in @maven.
+local_repository(
+  name = "my_compliance",
+  path = "compliance",
+)
+
+
+# Point to parent for testing. You would use http_archive in real life.
+http_archive(
+    name = "rules_jvm_external",
+    # path = "..",
+    urls = ["file:///tmp/rje.tar"],
+    patch_cmds = [
+      "/bin/pwd >/tmp/toast.pwd",
+      "./use_license_classifier.sh my_compliance",
+      # "/usr/local/google/home/aiuto/ws/rules_jvm_external/license_demo/splice_lc.sh",
+    ],
+)
+
+load("@rules_jvm_external//:defs.bzl", "maven_install")
+
+maven_install(
+    artifacts = [
+        "junit:junit:4.12",
+        "com.google.guava:guava:28.0-jre",
+    ],
+    fetch_sources = True,
+    repositories = [
+        "http://uk.maven.org/maven2",
+        "https://jcenter.bintray.com/",
+    ],
+)

license_demo/compliance/BUILD

@@ -0,0 +1,16 @@
+# Organization local compliance rules go here
+
+load("@rules_license//rules:license.bzl", "license")
+
+package(
+    default_applicable_licenses = [":license"],
+    default_visibility = ["//visibility:public"],
+)
+
+license(
+    name = "apache",
+    license_kinds = [
+        "@rules_license//licenses/spdx:Apache-2.0"
+    ],
+    license_text = "LICENSE_apache.txt",
+)

license_demo/compliance/LICENSE_apache.txt

@@ -0,0 +1 @@
+apache license

license_demo/compliance/license_classifier.bzl

@@ -0,0 +1,9 @@
+"""Users will provider their own.
+
+This is a respository rule.
+"""
+
+
+def lookup_license(url=None, sha256=None, maven_id=None):
+    print("==================================== yes")
+    return "@my_compliance//:apache"

private/dependency_tree_parser.bzl

@@ -17,6 +17,7 @@ This file contains parsing functions to turn a JSON-like dependency tree
 into target declarations (jvm_import) for the final @maven//:BUILD file.
 """
 
+load("//:license_classifier.bzl", "lookup_license")
 load("//private:coursier_utilities.bzl", "escape", "get_classifier", "get_packaging", "strip_packaging_and_classifier", "strip_packaging_and_classifier_and_version")
 
 JETIFY_INCLUDE_LIST_JETIFY_ALL = ["*"]
@@ -293,6 +294,12 @@ def _generate_imports(repository_ctx, dep_tree, explicit_artifacts, neverlink_ar
                 target_import_string.append("\tvisibility = [%s]," % (",".join(["\"%s\"" % v for v in default_visibilities])))
                 alias_visibility = "\tvisibility = [%s],\n" % (",".join(["\"%s\"" % v for v in default_visibilities]))
 
+
+            # Splice in the license
+            lic = lookup_license(maven_id = simple_coord)
+            if lic:
+               target_import_string.append("\tapplicable_licenses = [\"%s\"]," % lic)
+
             # 9. Finish the java_import rule.
             #
             # java_import(

use_license_classifier.sh

@@ -0,0 +1,20 @@
+#!/bin/bash -e
+#
+# Replace the no-op fallback license classifier with one implemented in
+# a repository of our choosing
+
+
+if [[ $# != 1 ]] ; then
+  echo 'usage: use_license_classifier.sh REPOSITORY_NAME'
+  exit 1
+fi
+
+cat >license_classifier.bzl  <<INP
+# This file is generated by the patch command "use_license_classifier.sh".
+# It overwrites the default license_classifier.bzl
+
+load("@${1}//:license_classifier.bzl", _ll = "lookup_license")
+
+def lookup_license(url=None, sha256=None, maven_id=None):
+    return _ll(url=url, sha256=sha256, maven_id=maven_id)
+INP