feat: allow attaching platform constraints to dependency trees imported through maven.install

MODULE.bazel

@@ -323,6 +323,9 @@ dev_maven.install(
         "https://repo1.maven.org/maven2",
         "https://maven.google.com",
     ],
+    targets_compatible_with = [
+        "@platforms//os:android",
+    ],
 )
 dev_maven.install(
     name = "m2local_testing",

README.md

@@ -533,7 +533,9 @@ java_library(
 
 If your WORKSPACE contains several projects that use different versions of the
 same artifact, you can specify multiple `maven_install` declarations in the
-WORKSPACE, with a unique repository name for each of them.
+WORKSPACE, with a unique repository name for each of them. You can ensure that
+builds do not cross this division using [platform
+constraints](https://bazel.build/extending/platforms).
 
 For example, if you want to use the JRE version of Guava for a server app, and
 the Android version for an Android app, you can specify two `maven_install`
@@ -548,6 +550,7 @@ maven_install(
     repositories = [
         "https://repo1.maven.org/maven2",
     ],
+    targets_compatible_with = ["@platforms//os:linux"],
 )
 
 maven_install(
@@ -558,6 +561,7 @@ maven_install(
     repositories = [
         "https://repo1.maven.org/maven2",
     ],
+    targets_compatible_with = ["@platforms//os:android"],
 )
 ```
 

WORKSPACE

@@ -526,6 +526,9 @@ maven_install(
     repositories = [
         "https://repo1.maven.org/maven2",
     ],
+    targets_compatible_with = [
+        "@platforms//os:android",
+    ],
 )
 
 maven_install(

private/dependency_tree_parser.bzl

@@ -313,7 +313,34 @@ package_info(
     target_import_string.append("\tvisibility = [%s]," % (",".join(["\"%s\"" % t for t in target_visibilities])))
     alias_visibility = "\tvisibility = [%s],\n" % (",".join(["\"%s\"" % t for t in target_visibilities]))
 
-    # 9. Finish the java_import rule.
+    # 9. If `targets_compatible_with` is configured, set it on non-transitive dependencies; the effect applies transitively already.
+    #    visibility only for non-transitive dependencies.
+    #
+    # java_import(
+    # 	name = "org_hamcrest_hamcrest_library",
+    # 	jars = ["https/repo1.maven.org/maven2/org/hamcrest/hamcrest-library/1.3/hamcrest-library-1.3.jar"],
+    # 	srcjar = "https/repo1.maven.org/maven2/org/hamcrest/hamcrest-library/1.3/hamcrest-library-1.3-sources.jar",
+    # 	deps = [
+    # 		":org_hamcrest_hamcrest_core",
+    # 	],
+    #   tags = [
+    #       "maven_coordinates=org.hamcrest:hamcrest.library:1.3"],
+    #       "maven_url=https://repo1.maven.org/maven/org/hamcrest/hamcrest-core/1.3/hamcrest-core-1.3.jar",
+    #       "maven:compile-only",
+    #   ],
+    #   neverlink = True,
+    #   testonly = True,
+    #   visibility = ["//visibility:public"],
+    #   targets_compatible_with = [
+    #       "@platforms//os:linux",
+    #   ],
+    if repository_ctx.attr.targets_compatible_with:
+        target_import_string.append("\ttarget_compatible_with = [")
+        for t in repository_ctx.attr.targets_compatible_with:
+            target_import_string.append("\t\t\"%s\"," % t)
+        target_import_string.append("\t],")
+
+    # 10. Finish the java_import rule.
     #
     # java_import(
     # 	name = "org_hamcrest_hamcrest_library",
@@ -334,7 +361,7 @@ package_info(
 
     to_return.append("\n".join(target_import_string))
 
-    # 10. Create a versionless alias target
+    # 11. Create a versionless alias target
     #
     # alias(
     #   name = "org_hamcrest_hamcrest_library_1_3",
@@ -360,7 +387,7 @@ processor_class = "{processor_class}",
             ),
         )
 
-    # 11. If using maven_install.json, use a genrule to copy the file from the http_file
+    # 12. If using maven_install.json, use a genrule to copy the file from the http_file
     # repository into this repository.
     #
     # genrule(

private/extensions/maven.bzl

@@ -63,6 +63,11 @@ install = tag_class(
         ),
         "strict_visibility_value": attr.label_list(default = ["//visibility:private"]),
 
+        "targets_compatible_with": attr.label_list(
+            doc = "Platform constraints to add to the repository's targets.",
+            default = [],
+        ),
+
         # Android support
         "aar_import_bzl_label": attr.string(default = DEFAULT_AAR_IMPORT_LABEL, doc = "The label (as a string) to use to import aar_import from"),
         "use_starlark_android_rules": attr.bool(default = False, doc = "Whether to use the native or Starlark version of the Android rules."),
@@ -222,6 +227,7 @@ def maven_impl(mctx):
     # - version_conflict_policy: string. Fails build if different and not a default.
     # - ignore_empty_files: Treat jars that are empty as if they were not found.
     # - additional_coursier_options: Additional options that will be passed to coursier.
+    # - targets_compatible_with: a string list. Build will fail is duplicated and different.
 
     # Mapping of `name`s to a list of `bazel_module.name`. This will allow us to
     # warn users when more than one module attempts to update a maven repo
@@ -344,6 +350,13 @@ def maven_impl(mctx):
 
             repo["additional_coursier_options"] = repo.get("additional_coursier_options", []) + getattr(install, "additional_coursier_options", [])
 
+            repo["targets_compatible_with"] = _fail_if_different(
+                "targets_compatible_with",
+                repo.get("targets_compatible_with"),
+                install.targets_compatible_with,
+                [None, []],
+            )
+
             repos[install.name] = repo
 
     for (repo_name, known_names) in repo_name_2_module_name.items():
@@ -441,6 +454,7 @@ def maven_impl(mctx):
                 duplicate_version_warning = repo.get("duplicate_version_warning"),
                 ignore_empty_files = repo.get("ignore_empty_files"),
                 additional_coursier_options = repo.get("additional_coursier_options"),
+                targets_compatible_with = repo.get("targets_compatible_with"),
             )
         else:
             workspace_prefix = "@@" if bazel_features.external_deps.is_bzlmod_enabled else "@"
@@ -502,6 +516,7 @@ def maven_impl(mctx):
                 duplicate_version_warning = repo.get("duplicate_version_warning"),
                 excluded_artifacts = excluded_artifacts_json,
                 repin_instructions = repo.get("repin_instructions"),
+                targets_compatible_with = repo.get("targets_compatible_with"),
             )
 
             if repo.get("generate_compat_repositories"):

private/rules/coursier.bzl

@@ -1427,6 +1427,10 @@ pinned_coursier_fetch = repository_rule(
         "excluded_artifacts": attr.string_list(default = []),  # only used for hash generation
         # Use @@// to refer to the main repo with Bzlmod.
         "_workspace_label": attr.label(default = ("@@" if str(Label("//:invalid")).startswith("@@") else "@") + "//does/not:exist"),
+        "targets_compatible_with": attr.label_list(
+            doc = "Platform constraints to add to the repository's targets.",
+            default = [],
+        ),
     },
     implementation = _pinned_coursier_fetch_impl,
 )
@@ -1494,6 +1498,10 @@ coursier_fetch = repository_rule(
             doc = "Name of the corresponding pinned repo for this repo. Presence implies that this is an unpinned repo.",
             mandatory = False,
         ),
+        "targets_compatible_with": attr.label_list(
+            doc = "Platform constraints to add to the repository's targets.",
+            default = [],
+        ),
     },
     environ = [
         "JAVA_HOME",

private/rules/maven_install.bzl

@@ -28,7 +28,9 @@ def maven_install(
         duplicate_version_warning = "warn",
         repin_instructions = None,
         ignore_empty_files = False,
-        additional_coursier_options = []):
+        additional_coursier_options = [],
+        targets_compatible_with = [],
+    ):
     """Resolves and fetches artifacts transitively from Maven repositories.
 
     This macro runs a repository rule that invokes the Coursier CLI to resolve
@@ -80,6 +82,7 @@ def maven_install(
       repin_instructions: Instructions to re-pin dependencies in your repository. Will be shown when re-pinning is required.
       ignore_empty_files: Treat jars that are empty as if they were not found.
       additional_coursier_options: Additional options that will be passed to coursier.
+      targets_compatible_with: Platform constraints to add to the repository's targets.
     """
     if boms and resolver == "coursier":
         fail("The coursier resolver does not support resolving Maven BOMs. Please use another resolver.")
@@ -143,6 +146,7 @@ def maven_install(
             duplicate_version_warning = duplicate_version_warning,
             ignore_empty_files = ignore_empty_files,
             additional_coursier_options = additional_coursier_options,
+            targets_compatible_with = targets_compatible_with,
         )
 
     else:
@@ -173,6 +177,7 @@ def maven_install(
             use_starlark_android_rules = use_starlark_android_rules,
             aar_import_bzl_label = aar_import_bzl_label,
             repin_instructions = repin_instructions,
+            targets_compatible_with = targets_compatible_with,
             # Extra arguments only used for hash generation
             excluded_artifacts = excluded_artifacts_json_strings,
         )

tests/unit/jvm_import/BUILD

@@ -15,6 +15,7 @@
 load("@bazel_skylib//rules:build_test.bzl", "build_test")
 load("@rules_java//java:defs.bzl", "java_import")
 load(":jvm_import_test.bzl", "jvm_import_test_suite")
+load(":platform_transition_jar.bzl", "platform_transition_jar")
 
 java_import(
     name = "java_import_that_consumes_the_downloaded_file_directly",
@@ -29,4 +30,41 @@ build_test(
     ],
 )
 
+platform(
+    name = "android",
+    constraint_values = ["@platforms//os:android"],
+)
+
+platform(
+    name = "linux",
+    constraint_values = ["@platforms//os:linux"],
+)
+
+# Platform constraint is valid on Android but invalid on Linux:
+#
+#     maven_install(
+#        name = "jvm_import_test",
+#        # ...
+#        targets_compatible_with = ["@platforms//os:android"],
+#        # ...
+#     )
+platform_transition_jar(
+    name = "findbugs_for_android",
+    src = "@jvm_import_test//:com_google_code_findbugs_jsr305_3_0_2",
+    platform = ":android",
+)
+
+platform_transition_jar(
+    name = "findbugs_for_linux",
+    src = "@jvm_import_test//:com_google_code_findbugs_jsr305_3_0_2",
+    platform = ":linux",
+)
+
+build_test(
+    name = "test_does_jar_artifact_work_with_matching_platform_constraint",
+    targets = [
+        ":findbugs_for_android",
+    ],
+)
+
 jvm_import_test_suite(name = "jvm_import_tests")

tests/unit/jvm_import/jvm_import_test.bzl

@@ -88,6 +88,16 @@ does_jvm_import_export_a_package_provider_test = analysistest.make(
     },
 )
 
+def _does_jvm_import_enforce_platform_constraints_impl(ctx):
+    env = analysistest.begin(ctx)
+    asserts.expect_failure(env, expected_failure_msg = "didn't satisfy constraint")
+    return analysistest.end(env)
+
+does_jvm_import_enforce_platform_constraints_test = analysistest.make(
+    _does_jvm_import_enforce_platform_constraints_impl,
+    expect_failure = True,
+)
+
 def _does_non_jvm_import_target_carry_metadata(ctx):
     env = analysistest.begin(ctx)
 
@@ -121,6 +131,10 @@ def jvm_import_test_suite(name):
         target_under_test = "@jvm_import_test//:com_google_code_findbugs_jsr305",
         src = "@jvm_import_test//:com_google_code_findbugs_jsr305",
     )
+    does_jvm_import_enforce_platform_constraints_test(
+        name = "does_jvm_import_enforce_platform_constraints_test",
+        target_under_test = ":findbugs_for_linux",
+    )
 
     # TODO: restore once https://github.com/bazelbuild/rules_license/issues/154 is resolved
     #    does_non_jvm_import_target_carry_metadata_test(

tests/unit/jvm_import/platform_transition_jar.bzl

@@ -0,0 +1,31 @@
+def _xsitn_impl(settings, attr):
+    return {"//command_line_option:platforms": str(attr.platform)}
+
+_transition = transition(
+    implementation = _xsitn_impl,
+    inputs = [],
+    outputs = ["//command_line_option:platforms"],
+)
+
+def _rule_impl(ctx):
+    return [
+        DefaultInfo(files = depset(transitive = [ctx.attr.src[0][DefaultInfo].files])),
+    ]
+
+platform_transition_jar = rule(
+    implementation = _rule_impl,
+    attrs = {
+        "src": attr.label(
+            cfg = _transition,
+        ),
+        "platform": attr.label(),
+        "_allowlist_function_transition": attr.label(
+            default = "@bazel_tools//tools/allowlists/function_transition_allowlist",
+        ),
+    },
+    doc = """
+        Depend on a JAR for a specified platform.
+        This isn't typical usage - for the most part, Java builds should use a consistent config.
+        Using a transition enables modelling multi-platform builds within the build system for the purposes of testing.
+    """,
+)