Add an option so we can indicate that no java source jars are produced

scala/private/rule_impls.bzl

@@ -199,6 +199,7 @@ JavaFiles: {java_files}
 Manifest: {manifest}
 Plugins: {plugin_arg}
 PrintCompileTime: {print_compile_time}
+ExpectJavaOutput: {expect_java_output}
 ResourceDests: {resource_dest}
 ResourceJars: {resource_jars}
 ResourceSrcs: {resource_src}
@@ -213,6 +214,7 @@ StatsfileOutput: {statsfile_output}
       manifest = ctx.outputs.manifest.path,
       scala_opts = ",".join(scalacopts),
       print_compile_time = ctx.attr.print_compile_time,
+      expect_java_output = ctx.attr.expect_java_output,
       plugin_arg = plugin_arg,
       cp = compiler_classpath,
       classpath_resource_src = _join_path(classpath_resources),
@@ -287,7 +289,7 @@ def _interim_java_provider_for_java_compilation(scala_output):
 
 def try_to_compile_java_jar(ctx, scala_output, all_srcjars, java_srcs,
                             implicit_junit_deps_needed_for_java_compilation):
-  if not java_srcs and not all_srcjars:
+  if not java_srcs and (not (all_srcjars and ctx.attr.expect_java_output)):
     return False
 
   providers_of_dependencies = collect_java_providers_of(ctx.attr.deps)

scala/scala.bzl

@@ -112,6 +112,7 @@ _common_attrs_for_plugin_bootstrapping = {
     "jvm_flags": attr.string_list(),
     "scalac_jvm_flags": attr.string_list(),
     "javac_jvm_flags": attr.string_list(),
+    "expect_java_output": attr.bool(default = True, mandatory = False),
     "print_compile_time": attr.bool(default = False, mandatory = False),
 }
 

src/java/io/bazel/rulesscala/scalac/CompileOptions.java

@@ -9,6 +9,7 @@ public class CompileOptions {
   public final String manifestPath;
   public final String[] scalaOpts;
   public final boolean printCompileTime;
+  public final boolean expectJavaOutput;
   public final String[] pluginArgs;
   public final String classpath;
   public final String[] files;
@@ -36,12 +37,17 @@ public CompileOptions(List<String> args) {
 
     scalaOpts = getCommaList(argMap, "ScalacOpts");
     printCompileTime = booleanGetOrFalse(argMap, "PrintCompileTime");
+    expectJavaOutput = booleanGetOrTrue(argMap, "ExpectJavaOutput");
     pluginArgs = buildPluginArgs(getOrEmpty(argMap, "Plugins"));
     classpath = getOrError(argMap, "Classpath", "Must supply the classpath arg");
     files = getCommaList(argMap, "Files");
 
     javaFiles = getCommaList(argMap, "JavaFiles");
 
+    if (!expectJavaOutput && javaFiles.length != 0) {
+      throw new RuntimeException("Cannot hava java source files when no expected java output");
+    }
+
     sourceJars = getCommaList(argMap, "SourceJars");
     iJarEnabled = booleanGetOrFalse(argMap, "EnableIjar");
     if (iJarEnabled) {
@@ -150,6 +156,16 @@ private static boolean booleanGetOrFalse(Map<String, String> m, String k) {
     return false;
   }
 
+  private static boolean booleanGetOrTrue(Map<String, String> m, String k) {
+    if (m.containsKey(k)) {
+      String v = m.get(k);
+      if (v.trim().equals("False") || v.trim().equals("false")) {
+        return false;
+      }
+    }
+    return true;
+  }
+
   public static String[] buildPluginArgs(String packedPlugins) {
     String[] pluginElements = packedPlugins.split(",");
     int numPlugins = 0;

src/java/io/bazel/rulesscala/scalac/ScalacProcessor.java

@@ -47,6 +47,11 @@ public void processRequest(List<String> args) throws Exception {
       List<File> scalaJarFiles = filterFilesByExtension(jarFiles, ".scala");
       List<File> javaJarFiles = filterFilesByExtension(jarFiles, ".java");
 
+      if (!ops.expectJavaOutput && !javaJarFiles.isEmpty()) {
+        throw new RuntimeException(
+            "Found java files in source jars but expect Java output is set to false");
+      }
+
       String[] scalaSources = collectSrcJarSources(ops.files, scalaJarFiles, javaJarFiles);
 
       String[] javaSources = GenericWorker.appendToString(ops.javaFiles, javaJarFiles);

test/src/main/scala/scalarules/test/twitter_scrooge/BUILD

@@ -200,3 +200,13 @@ sh_test(
     ],
     data = [":justscrooges"],
 )
+
+sh_test(
+    name = "java_jar_not_on_classpath",
+    srcs = ["grep.sh"],
+    args = [
+        "_java.jar",
+        "$(location :justscrooges)",
+    ],
+    data = [":justscrooges"],
+)

test_expect_failure/java_in_src_jar_when_disabled/BUILD

@@ -0,0 +1,9 @@
+load("//scala:scala.bzl", "scala_library")
+
+scala_library(
+    name = "java_source_jar",
+    # JavaSourceJar.srcjar was constructed with
+    # `jar -cfM JavaSourceJar.srcjar JavaSource.java`
+    srcs = ["JavaSourceJar.srcjar"],
+    expect_java_output = False,
+)

test_rules_scala.sh

@@ -185,6 +185,14 @@ test_scala_library_expect_failure_on_missing_direct_java() {
   test_expect_failure_or_warning_on_missing_direct_deps_with_expected_message "${expected_message}" $test_target "--strict_java_deps=error"
 }
 
+test_scala_library_expect_failure_on_java_in_src_jar_when_disabled() {
+  test_target='//test_expect_failure/java_in_src_jar_when_disabled:java_source_jar'
+
+  expected_message=".*Found java files in source jars but expect Java output is set to false"
+
+  test_expect_failure_with_message "${expected_message}" $test_target
+}
+
 test_scala_library_expect_better_failure_message_on_missing_transitive_dependency_labels_from_other_jvm_rules() {
   transitive_target='.*transitive_dependency_ijar.jar'
   direct_target='//test_expect_failure/missing_direct_deps/internal_deps:direct_java_provider_dependency'
@@ -858,6 +866,7 @@ $runner test_scala_library_expect_no_recompilation_on_internal_change_of_scala_d
 $runner test_scala_library_expect_no_recompilation_on_internal_change_of_java_dependency
 $runner test_scala_library_expect_no_java_recompilation_on_internal_change_of_scala_sibling
 $runner test_scala_library_expect_failure_on_missing_direct_java
+$runner test_scala_library_expect_failure_on_java_in_src_jar_when_disabled
 $runner bazel run test:test_scala_proto_server
 $runner test_scala_library_expect_failure_on_missing_direct_deps_warn_mode_java
 $runner test_scala_library_expect_better_failure_message_on_missing_transitive_dependency_labels_from_other_jvm_rules

twitter_scrooge/twitter_scrooge.bzl

@@ -302,4 +302,5 @@ def scrooge_scala_library(name,
       ],
       jvm_flags = jvm_flags,
       visibility = visibility,
+      expect_java_output = False,
   )