Add scala_doc rule

README.md

@@ -21,6 +21,7 @@ This project defines core build rules for [Scala](https://www.scala-lang.org/) t
 * [scalapb_proto_library](docs/scalapb_proto_library.md)
 * [scala_toolchain](docs/scala_toolchain.md)
 * [scala_import](docs/scala_import.md)
+* [scala_doc](docs/scala_doc.md)
 
 ## Getting started
 

docs/scala_doc.md

@@ -0,0 +1,42 @@
+# scala_doc
+
+```python
+scala_binary(
+    name,
+    deps,
+)
+```
+
+`scala_doc` generates [Scaladoc](https://docs.scala-lang.org/style/scaladoc.html) for sources
+for targets, including sources from upstream deps. Readily hostable HTML is written to a `name.html` output folder.
+
+Scaladoc can be somewhat slow to build. In that case, you can tell Bazel to build this target manually,
+i.e. only when named explicitly and not through wildcards: `tags = ["manual"]`.
+
+## Example
+
+scala_doc(
+    name = "scala_docs",
+    tags = ["manual"],
+    deps = [
+        ":target1",
+        ":target2",
+        ":anothertarget",
+    ],
+)
+
+# Use pkg_tar to tarball up
+# https://docs.bazel.build/versions/master/be/pkg.html#pkg_tar
+pkg_tar(
+    name = "scala_docs_archive",
+    srcs = [":scala_docs"],
+    extension = "tar.gz",
+)
+```
+
+## Attributes
+
+| Attribute name        | Description                                           |
+| --------------------- | ----------------------------------------------------- |
+| name                  | `Name, required` <br> A unique name for this target.
+| deps                  | `List of labels, optional` <br> Labels for which you want to create scaladoc.

scala/private/common.bzl

@@ -36,6 +36,23 @@ def collect_jars(
     else:
         return _collect_jars_when_dependency_analyzer_is_on(dep_targets)
 
+def collect_plugin_paths(plugins):
+    """Get the actual jar paths of plugins as a depset."""
+    paths = []
+    for p in plugins:
+        if hasattr(p, "path"):
+            paths.append(p)
+        elif hasattr(p, "scala"):
+            paths.extend([j.class_jar for j in p.scala.outputs.jars])
+        elif hasattr(p, "java"):
+            paths.extend([j.class_jar for j in p.java.outputs.jars])
+            # support http_file pointed at a jar. http_jar uses ijar,
+            # which breaks scala macros
+
+        elif hasattr(p, "files"):
+            paths.extend([f for f in p.files if not_sources_jar(f.basename)])
+    return depset(paths)
+
 def _collect_jars_when_dependency_analyzer_is_off(
         dep_targets,
         unused_dependency_checker_is_off,

scala/private/rule_impls.bzl

@@ -26,6 +26,7 @@ load(
     ":common.bzl",
     "add_labels_of_jars_to",
     "collect_jars",
+    "collect_plugin_paths",
     "collect_srcjars",
     "create_java_provider",
     "not_sources_jar",
@@ -127,22 +128,6 @@ touch {statsfile}
         arguments = [],
     )
 
-def _collect_plugin_paths(plugins):
-    paths = []
-    for p in plugins:
-        if hasattr(p, "path"):
-            paths.append(p)
-        elif hasattr(p, "scala"):
-            paths.extend([j.class_jar for j in p.scala.outputs.jars])
-        elif hasattr(p, "java"):
-            paths.extend([j.class_jar for j in p.java.outputs.jars])
-            # support http_file pointed at a jar. http_jar uses ijar,
-            # which breaks scala macros
-
-        elif hasattr(p, "files"):
-            paths.extend([f for f in p.files if not_sources_jar(f.basename)])
-    return depset(paths)
-
 def _expand_location(ctx, flags):
     return [ctx.expand_location(f, ctx.attr.data) for f in flags]
 
@@ -172,7 +157,7 @@ def compile_scala(
         unused_dependency_checker_mode = "off",
         unused_dependency_checker_ignored_targets = []):
     # look for any plugins:
-    plugins = _collect_plugin_paths(plugins)
+    plugins = collect_plugin_paths(plugins)
     internal_plugin_jars = []
     dependency_analyzer_mode = "off"
     compiler_classpath_jars = cjars

scala/scala.bzl

@@ -32,6 +32,10 @@ load(
     "@io_bazel_rules_scala//scala:plusone.bzl",
     _collect_plus_one_deps_aspect = "collect_plus_one_deps_aspect",
 )
+load(
+    "@io_bazel_rules_scala//scala:scala_doc.bzl",
+    _scala_doc = "scala_doc",
+)
 
 _launcher_template = {
     "_java_stub_template": attr.label(
@@ -700,3 +704,5 @@ def scala_specs2_junit_test(name, **kwargs):
         suite_class = "io.bazel.rulesscala.specs2.Specs2DiscoveredTestSuite",
         **kwargs
     )
+
+scala_doc = _scala_doc

scala/scala_doc.bzl

@@ -0,0 +1,91 @@
+"""Scaladoc support"""
+
+load("@io_bazel_rules_scala//scala/private:common.bzl", "collect_plugin_paths")
+
+ScaladocAspectInfo = provider(fields = [
+    "src_files",
+    "compile_jars",
+    "plugins",
+])
+
+def _scaladoc_aspect_impl(target, ctx):
+    """Collect source files and compile_jars from JavaInfo-returning deps."""
+
+    # We really only care about visited targets with srcs, so only look at those.
+    if hasattr(ctx.rule.attr, "srcs"):
+        # Collect only Java and Scala sources enumerated in visited targets.
+        src_files = depset(direct = [file for file in ctx.rule.files.srcs if file.extension.lower() in ["java", "scala"]])
+
+        # Collect compile_jars from visited targets' deps.
+        compile_jars = depset(transitive = [dep[JavaInfo].compile_jars for dep in ctx.rule.attr.deps if JavaInfo in dep])
+
+        plugins = depset()
+        if hasattr(ctx.rule.attr, "plugins"):
+            plugins = depset(direct = ctx.rule.attr.plugins)
+
+        return [ScaladocAspectInfo(
+            src_files = src_files,
+            compile_jars = compile_jars,
+            plugins = plugins,
+        )]
+    else:
+        return []
+
+scaladoc_aspect = aspect(
+    implementation = _scaladoc_aspect_impl,
+    attr_aspects = ["deps"],
+    required_aspect_providers = [
+        [JavaInfo],
+    ],
+)
+
+def _scala_doc_impl(ctx):
+    # scaladoc warns if you don't have the output directory already created, which is annoying.
+    output_path = ctx.actions.declare_directory("{}.html".format(ctx.attr.name))
+
+    # Collect all source files and compile_jars to pass to scaladoc by way of an aspect.
+    src_files = depset(transitive = [dep[ScaladocAspectInfo].src_files for dep in ctx.attr.deps])
+    compile_jars = depset(transitive = [dep[ScaladocAspectInfo].compile_jars for dep in ctx.attr.deps])
+
+    # Get the 'real' paths to the plugin jars.
+    plugins = collect_plugin_paths(depset(transitive = [dep[ScaladocAspectInfo].plugins for dep in ctx.attr.deps]))
+
+    # Construct the full classpath depset since we need to add compiler plugins too.
+    classpath = depset(transitive = [plugins, compile_jars])
+
+    # Construct scaladoc args, which also include scalac args.
+    # See `scaladoc -help` for more information.
+    args = ctx.actions.args()
+    args.add("-usejavacp")
+    args.add("-d", output_path.path)
+    args.add_all(plugins, format_each = "-Xplugin:%s")
+    args.add_joined("-classpath", classpath, join_with = ":")
+    args.add_all(src_files)
+
+    # Run the scaladoc tool!
+    ctx.actions.run(
+        inputs = depset(transitive = [src_files, classpath]),
+        outputs = [output_path],
+        executable = ctx.attr._scaladoc.files_to_run.executable,
+        mnemonic = "ScalaDoc",
+        progress_message = "scaladoc {}".format(ctx.label),
+        arguments = [args],
+    )
+
+    return [DefaultInfo(files = depset(direct = [output_path]))]
+
+scala_doc = rule(
+    attrs = {
+        "deps": attr.label_list(
+            aspects = [scaladoc_aspect],
+            providers = [JavaInfo],
+        ),
+        "_scaladoc": attr.label(
+            cfg = "host",
+            executable = True,
+            default = Label("//src/scala/io/bazel/rules_scala/scaladoc_support:scaladoc_generator"),
+        ),
+    },
+    doc = "Generate Scaladoc HTML documentation for source files in from the given dependencies.",
+    implementation = _scala_doc_impl,
+)

src/scala/io/bazel/rules_scala/scaladoc_support/BUILD

@@ -0,0 +1,17 @@
+load("//scala:scala.bzl", "scala_binary")
+
+# A simple scala_binary to run scaladoc.
+# `bazel run` this target with "-help" as a param for usage text:
+# bazel run -- "//src/scala/io/bazel/rules_scala/scaladoc_support:scaladoc_generator" -help
+scala_binary(
+    name = "scaladoc_generator",
+    main_class = "scala.tools.nsc.ScalaDoc",
+    visibility = ["//visibility:public"],
+    runtime_deps = [
+        "//external:io_bazel_rules_scala/dependency/scala/parser_combinators",
+        "//external:io_bazel_rules_scala/dependency/scala/scala_compiler",
+        "//external:io_bazel_rules_scala/dependency/scala/scala_library",
+        "//external:io_bazel_rules_scala/dependency/scala/scala_reflect",
+        "//external:io_bazel_rules_scala/dependency/scala/scala_xml",
+    ],
+)

test/BUILD

@@ -3,6 +3,7 @@ package(default_testonly = 1)
 load(
     "//scala:scala.bzl",
     "scala_binary",
+    "scala_doc",
     "scala_library",
     "scala_test",
     "scala_macro_library",
@@ -137,6 +138,15 @@ scala_library(
     deps = ["ExportOnly"],
 )
 
+scala_doc(
+    name = "ScalaDoc",
+    deps = [
+        ":HelloLib",
+        ":OtherLib",
+        "//test/src/main/scala/scalarules/test/compiler_plugin",  # brings kind-projector compiler plugin with it
+    ]
+)
+
 scala_library(
     name = "UnusedLib",
     srcs = ["UnusedLib.scala"]

test/src/main/scala/scalarules/test/compiler_plugin/BUILD.bazel

@@ -2,6 +2,7 @@ load("//scala:scala.bzl", "scala_library")
 
 scala_library(
     name = "compiler_plugin",
-    srcs = [ "KindProjected.scala" ],
-    plugins = ["@org_spire_math_kind_projector//jar"]
-)
+    srcs = ["KindProjected.scala"],
+    plugins = ["@org_spire_math_kind_projector//jar"],
+    visibility = ["//visibility:public"],
+)