Enable scala_macro_library targets to have dependencies (#1681)

* Enabled ijar for scala_macro_library targets

* Export a ScalaInfo provider

* Include macros' transitive runtime dependencies on the compile classpath

---------

Co-authored-by: Jaden Peterson <jpeterson@lucidchart.com>

scala/private/common.bzl

@@ -1,5 +1,6 @@
 load("@io_bazel_rules_scala//scala:jars_to_labels.bzl", "JarsToLabelsInfo")
 load("@io_bazel_rules_scala//scala:plusone.bzl", "PlusOneDeps")
+load("@io_bazel_rules_scala//scala:providers.bzl", "ScalaInfo")
 load("@bazel_skylib//lib:paths.bzl", "paths")
 
 def write_manifest_file(actions, output_file, main_class):
@@ -22,6 +23,7 @@ def collect_jars(
     compile_jars = []
     runtime_jars = []
     deps_providers = []
+    macro_classpath = []
 
     for dep_target in dep_targets:
         # we require a JavaInfo for dependencies
@@ -50,11 +52,34 @@ def collect_jars(
                 java_provider.compile_jars.to_list(),
             )
 
+        # Macros are different from ordinary targets in that they’re used at compile time instead of at runtime. That
+        # means that both their compile-time classpath and runtime classpath are needed at compile time. We could have
+        # `scala_macro_library` targets include their runtime dependencies in their compile-time dependencies, but then
+        # we wouldn't have any guarantees classpath order.
+        #
+        # Consider the following scenario. Target A depends on targets B and C. Target C is a macro target, whereas
+        # target B isn't. Targets C depends on target B. If target A doesn't include the runtime version of target C on
+        # the compile classpath before the compile (`ijar`d) version of target B that target C depends on, then target A
+        # won't use the correct version of target B at compile-time when evaluating the macros contained in target C.
+        #
+        # For that reason, we opt for a different approach: have `scala_macro_library` targets export `JavaInfo`
+        # providers as normal, but put their transitive runtime dependencies first on the classpath. Note that we
+        # shouldn't encounter any issues with external dependencies, so long as they aren't `ijar`d.
+        if ScalaInfo in dep_target and dep_target[ScalaInfo].contains_macros:
+            macro_classpath.append(java_provider.transitive_runtime_jars)
+
+            add_labels_of_jars_to(
+                jars2labels,
+                dep_target,
+                [],
+                java_provider.transitive_runtime_jars.to_list(),
+            )
+
     return struct(
-        compile_jars = depset(transitive = compile_jars),
+        compile_jars = depset(order = "preorder", transitive = macro_classpath + compile_jars),
         transitive_runtime_jars = depset(transitive = runtime_jars),
         jars2labels = JarsToLabelsInfo(jars_to_labels = jars2labels),
-        transitive_compile_jars = depset(transitive = transitive_compile_jars),
+        transitive_compile_jars = depset(order = "preorder", transitive = macro_classpath + transitive_compile_jars),
         deps_providers = deps_providers,
     )
 

scala/private/phases/phase_compile.bzl

@@ -46,17 +46,6 @@ def phase_compile_library_for_plugin_bootstrapping(ctx, p):
     )
     return _phase_compile_default(ctx, p, args)
 
-def phase_compile_macro_library(ctx, p):
-    args = struct(
-        buildijar = False,
-        unused_dependency_checker_ignored_targets = [
-            target.label
-            for target in p.scalac_provider.default_macro_classpath + ctx.attr.exports +
-                          ctx.attr.unused_dependency_checker_ignored_targets
-        ],
-    )
-    return _phase_compile_default(ctx, p, args)
-
 def phase_compile_junit_test(ctx, p):
     args = struct(
         buildijar = False,

scala/private/phases/phase_scalainfo_provider.bzl

@@ -0,0 +1,14 @@
+load("//scala:providers.bzl", "ScalaInfo")
+
+def _phase_scalainfo_provider_implementation(contains_macros):
+    return struct(
+        external_providers = {
+            "ScalaInfo": ScalaInfo(contains_macros = contains_macros),
+        },
+    )
+
+def phase_scalainfo_provider_macro(ctx, p):
+    return _phase_scalainfo_provider_implementation(contains_macros = True)
+
+def phase_scalainfo_provider_non_macro(ctx, p):
+    return _phase_scalainfo_provider_implementation(contains_macros = False)

scala/private/phases/phases.bzl

@@ -7,18 +7,6 @@ load(
     _extras_phases = "extras_phases",
     _run_phases = "run_phases",
 )
-load(
-    "@io_bazel_rules_scala//scala/private:phases/phase_write_executable.bzl",
-    _phase_write_executable_common = "phase_write_executable_common",
-    _phase_write_executable_junit_test = "phase_write_executable_junit_test",
-    _phase_write_executable_repl = "phase_write_executable_repl",
-    _phase_write_executable_scalatest = "phase_write_executable_scalatest",
-)
-load(
-    "@io_bazel_rules_scala//scala/private:phases/phase_java_wrapper.bzl",
-    _phase_java_wrapper_common = "phase_java_wrapper_common",
-    _phase_java_wrapper_repl = "phase_java_wrapper_repl",
-)
 load(
     "@io_bazel_rules_scala//scala/private:phases/phase_collect_jars.bzl",
     _phase_collect_jars_common = "phase_collect_jars_common",
@@ -27,46 +15,62 @@ load(
     _phase_collect_jars_repl = "phase_collect_jars_repl",
     _phase_collect_jars_scalatest = "phase_collect_jars_scalatest",
 )
+load("@io_bazel_rules_scala//scala/private:phases/phase_collect_exports_jars.bzl", _phase_collect_exports_jars = "phase_collect_exports_jars")
+load("@io_bazel_rules_scala//scala/private:phases/phase_collect_srcjars.bzl", _phase_collect_srcjars = "phase_collect_srcjars")
 load(
     "@io_bazel_rules_scala//scala/private:phases/phase_compile.bzl",
     _phase_compile_binary = "phase_compile_binary",
     _phase_compile_common = "phase_compile_common",
     _phase_compile_junit_test = "phase_compile_junit_test",
     _phase_compile_library = "phase_compile_library",
     _phase_compile_library_for_plugin_bootstrapping = "phase_compile_library_for_plugin_bootstrapping",
-    _phase_compile_macro_library = "phase_compile_macro_library",
     _phase_compile_repl = "phase_compile_repl",
     _phase_compile_scalatest = "phase_compile_scalatest",
 )
-load(
-    "@io_bazel_rules_scala//scala/private:phases/phase_runfiles.bzl",
-    _phase_runfiles_common = "phase_runfiles_common",
-    _phase_runfiles_library = "phase_runfiles_library",
-    _phase_runfiles_scalatest = "phase_runfiles_scalatest",
-)
 load(
     "@io_bazel_rules_scala//scala/private:phases/phase_coverage.bzl",
     _phase_coverage_common = "phase_coverage_common",
     _phase_coverage_library = "phase_coverage_library",
 )
+load("@io_bazel_rules_scala//scala/private:phases/phase_coverage_runfiles.bzl", _phase_coverage_runfiles = "phase_coverage_runfiles")
+load("@io_bazel_rules_scala//scala/private:phases/phase_declare_executable.bzl", _phase_declare_executable = "phase_declare_executable")
 load("@io_bazel_rules_scala//scala/private:phases/phase_default_info.bzl", _phase_default_info = "phase_default_info")
-load("@io_bazel_rules_scala//scala/private:phases/phase_scalac_provider.bzl", _phase_scalac_provider = "phase_scalac_provider")
-load("@io_bazel_rules_scala//scala/private:phases/phase_write_manifest.bzl", _phase_write_manifest = "phase_write_manifest")
-load("@io_bazel_rules_scala//scala/private:phases/phase_collect_srcjars.bzl", _phase_collect_srcjars = "phase_collect_srcjars")
-load("@io_bazel_rules_scala//scala/private:phases/phase_collect_exports_jars.bzl", _phase_collect_exports_jars = "phase_collect_exports_jars")
 load(
     "@io_bazel_rules_scala//scala/private:phases/phase_dependency.bzl",
     _phase_dependency_common = "phase_dependency_common",
     _phase_dependency_library_for_plugin_bootstrapping = "phase_dependency_library_for_plugin_bootstrapping",
 )
-load("@io_bazel_rules_scala//scala/private:phases/phase_declare_executable.bzl", _phase_declare_executable = "phase_declare_executable")
-load("@io_bazel_rules_scala//scala/private:phases/phase_merge_jars.bzl", _phase_merge_jars = "phase_merge_jars")
+load(
+    "@io_bazel_rules_scala//scala/private:phases/phase_java_wrapper.bzl",
+    _phase_java_wrapper_common = "phase_java_wrapper_common",
+    _phase_java_wrapper_repl = "phase_java_wrapper_repl",
+)
 load("@io_bazel_rules_scala//scala/private:phases/phase_jvm_flags.bzl", _phase_jvm_flags = "phase_jvm_flags")
+load("@io_bazel_rules_scala//scala/private:phases/phase_merge_jars.bzl", _phase_merge_jars = "phase_merge_jars")
+load(
+    "@io_bazel_rules_scala//scala/private:phases/phase_runfiles.bzl",
+    _phase_runfiles_common = "phase_runfiles_common",
+    _phase_runfiles_library = "phase_runfiles_library",
+    _phase_runfiles_scalatest = "phase_runfiles_scalatest",
+)
+load("@io_bazel_rules_scala//scala/private:phases/phase_scalac_provider.bzl", _phase_scalac_provider = "phase_scalac_provider")
 load("@io_bazel_rules_scala//scala/private:phases/phase_scalacopts.bzl", _phase_scalacopts = "phase_scalacopts")
-load("@io_bazel_rules_scala//scala/private:phases/phase_coverage_runfiles.bzl", _phase_coverage_runfiles = "phase_coverage_runfiles")
 load("@io_bazel_rules_scala//scala/private:phases/phase_scalafmt.bzl", _phase_scalafmt = "phase_scalafmt")
-load("@io_bazel_rules_scala//scala/private:phases/phase_test_environment.bzl", _phase_test_environment = "phase_test_environment")
+load(
+    "@io_bazel_rules_scala//scala/private:phases/phase_scalainfo_provider.bzl",
+    _phase_scalainfo_provider_macro = "phase_scalainfo_provider_macro",
+    _phase_scalainfo_provider_non_macro = "phase_scalainfo_provider_non_macro",
+)
 load("@io_bazel_rules_scala//scala/private:phases/phase_semanticdb.bzl", _phase_semanticdb = "phase_semanticdb")
+load("@io_bazel_rules_scala//scala/private:phases/phase_test_environment.bzl", _phase_test_environment = "phase_test_environment")
+load(
+    "@io_bazel_rules_scala//scala/private:phases/phase_write_executable.bzl",
+    _phase_write_executable_common = "phase_write_executable_common",
+    _phase_write_executable_junit_test = "phase_write_executable_junit_test",
+    _phase_write_executable_repl = "phase_write_executable_repl",
+    _phase_write_executable_scalatest = "phase_write_executable_scalatest",
+)
+load("@io_bazel_rules_scala//scala/private:phases/phase_write_manifest.bzl", _phase_write_manifest = "phase_write_manifest")
 
 # API
 run_phases = _run_phases
@@ -75,6 +79,10 @@ extras_phases = _extras_phases
 # scalac_provider
 phase_scalac_provider = _phase_scalac_provider
 
+# scalainfo_provider
+phase_scalainfo_provider_macro = _phase_scalainfo_provider_macro
+phase_scalainfo_provider_non_macro = _phase_scalainfo_provider_non_macro
+
 # collect_srcjars
 phase_collect_srcjars = _phase_collect_srcjars
 
@@ -128,7 +136,6 @@ phase_collect_jars_common = _phase_collect_jars_common
 phase_compile_binary = _phase_compile_binary
 phase_compile_library = _phase_compile_library
 phase_compile_library_for_plugin_bootstrapping = _phase_compile_library_for_plugin_bootstrapping
-phase_compile_macro_library = _phase_compile_macro_library
 phase_compile_junit_test = _phase_compile_junit_test
 phase_compile_repl = _phase_compile_repl
 phase_compile_scalatest = _phase_compile_scalatest

scala/private/rules/scala_binary.bzl

@@ -24,6 +24,7 @@ load(
     "phase_runfiles_common",
     "phase_scalac_provider",
     "phase_scalacopts",
+    "phase_scalainfo_provider_non_macro",
     "phase_semanticdb",
     "phase_write_executable_common",
     "phase_write_manifest",
@@ -36,6 +37,7 @@ def _scala_binary_impl(ctx):
         # customizable phases
         [
             ("scalac_provider", phase_scalac_provider),
+            ("scalainfo_provider", phase_scalainfo_provider_non_macro),
             ("write_manifest", phase_write_manifest),
             ("dependency", phase_dependency_common),
             ("collect_jars", phase_collect_jars_common),

scala/private/rules/scala_doc.bzl

@@ -1,10 +1,12 @@
 """Scaladoc support"""
 
+load("@io_bazel_rules_scala//scala:providers.bzl", "ScalaInfo")
 load("@io_bazel_rules_scala//scala/private:common.bzl", "collect_plugin_paths")
 
 ScaladocAspectInfo = provider(fields = [
     "src_files",  #depset[File]
     "compile_jars",  #depset[File]
+    "macro_classpath",  #depset[File]
     "plugins",  #depset[Target]
 ])
 
@@ -29,23 +31,28 @@ def _scaladoc_aspect_impl(target, ctx, transitive = True):
         if hasattr(ctx.rule.attr, "plugins"):
             plugins = depset(ctx.rule.attr.plugins)
 
+    macro_classpath = []
+
+    for dependency in ctx.rule.attr.deps:
+        if ScalaInfo in dependency and dependency[ScalaInfo].contains_macros:
+            macro_classpath.append(dependency[JavaInfo].transitive_runtime_jars)
+
     # Sometimes we only want to generate scaladocs for a single target and not all of its
     # dependencies
     transitive_srcs = depset()
-    transitive_compile_jars = depset()
     transitive_plugins = depset()
 
     if transitive:
         for dep in ctx.rule.attr.deps:
             if ScaladocAspectInfo in dep:
                 aspec_info = dep[ScaladocAspectInfo]
                 transitive_srcs = aspec_info.src_files
-                transitive_compile_jars = aspec_info.compile_jars
                 transitive_plugins = aspec_info.plugins
 
     return [ScaladocAspectInfo(
         src_files = depset(transitive = [src_files, transitive_srcs]),
-        compile_jars = depset(transitive = [compile_jars, transitive_compile_jars]),
+        compile_jars = depset(transitive = [compile_jars]),
+        macro_classpath = depset(transitive = macro_classpath),
         plugins = depset(transitive = [plugins, transitive_plugins]),
     )]
 
@@ -73,11 +80,15 @@ def _scala_doc_impl(ctx):
     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])
 
+    # See the documentation for `collect_jars` in `scala/private/common.bzl` to understand why this is prepended to the
+    # classpath
+    macro_classpath = depset(transitive = [dep[ScaladocAspectInfo].macro_classpath 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]).to_list())
 
     # Construct the full classpath depset since we need to add compiler plugins too.
-    classpath = depset(transitive = [plugins, compile_jars])
+    classpath = depset(transitive = [macro_classpath, plugins, compile_jars])
 
     # Construct scaladoc args, which also include scalac args.
     # See `scaladoc -help` for more information.

scala/private/rules/scala_junit_test.bzl

@@ -25,6 +25,7 @@ load(
     "phase_runfiles_common",
     "phase_scalac_provider",
     "phase_scalacopts",
+    "phase_scalainfo_provider_non_macro",
     "phase_semanticdb",
     "phase_test_environment",
     "phase_write_executable_junit_test",
@@ -42,6 +43,7 @@ def _scala_junit_test_impl(ctx):
         # customizable phases
         [
             ("scalac_provider", phase_scalac_provider),
+            ("scalainfo_provider", phase_scalainfo_provider_non_macro),
             ("write_manifest", phase_write_manifest),
             ("dependency", phase_dependency_common),
             ("collect_jars", phase_collect_jars_junit_test),

scala/private/rules/scala_library.bzl

@@ -25,7 +25,6 @@ load(
     "phase_collect_srcjars",
     "phase_compile_library",
     "phase_compile_library_for_plugin_bootstrapping",
-    "phase_compile_macro_library",
     "phase_coverage_common",
     "phase_coverage_library",
     "phase_default_info",
@@ -35,6 +34,8 @@ load(
     "phase_runfiles_library",
     "phase_scalac_provider",
     "phase_scalacopts",
+    "phase_scalainfo_provider_macro",
+    "phase_scalainfo_provider_non_macro",
     "phase_semanticdb",
     "phase_write_manifest",
     "run_phases",
@@ -63,6 +64,7 @@ def _scala_library_impl(ctx):
         # customizable phases
         [
             ("scalac_provider", phase_scalac_provider),
+            ("scalainfo_provider", phase_scalainfo_provider_non_macro),
             ("collect_srcjars", phase_collect_srcjars),
             ("write_manifest", phase_write_manifest),
             ("dependency", phase_dependency_common),
@@ -151,6 +153,7 @@ def _scala_library_for_plugin_bootstrapping_impl(ctx):
         # customizable phases
         [
             ("scalac_provider", phase_scalac_provider),
+            ("scalainfo_provider", phase_scalainfo_provider_non_macro),
             ("collect_srcjars", phase_collect_srcjars),
             ("write_manifest", phase_write_manifest),
             ("dependency", phase_dependency_library_for_plugin_bootstrapping),
@@ -226,13 +229,14 @@ def _scala_macro_library_impl(ctx):
         # customizable phases
         [
             ("scalac_provider", phase_scalac_provider),
+            ("scalainfo_provider", phase_scalainfo_provider_macro),
             ("collect_srcjars", phase_collect_srcjars),
             ("write_manifest", phase_write_manifest),
             ("dependency", phase_dependency_common),
             ("collect_jars", phase_collect_jars_macro_library),
             ("scalacopts", phase_scalacopts),
             ("semanticdb", phase_semanticdb),
-            ("compile", phase_compile_macro_library),
+            ("compile", phase_compile_library),
             ("coverage", phase_coverage_common),
             ("merge_jars", phase_merge_jars),
             ("runfiles", phase_runfiles_library),

scala/private/rules/scala_repl.bzl

@@ -24,6 +24,7 @@ load(
     "phase_runfiles_common",
     "phase_scalac_provider",
     "phase_scalacopts",
+    "phase_scalainfo_provider_non_macro",
     "phase_semanticdb",
     "phase_write_executable_repl",
     "phase_write_manifest",
@@ -36,6 +37,7 @@ def _scala_repl_impl(ctx):
         # customizable phases
         [
             ("scalac_provider", phase_scalac_provider),
+            ("scalainfo_provider", phase_scalainfo_provider_non_macro),
             ("write_manifest", phase_write_manifest),
             ("dependency", phase_dependency_common),
             # need scala-compiler for MainGenericRunner below

scala/private/rules/scala_test.bzl

@@ -25,6 +25,7 @@ load(
     "phase_runfiles_scalatest",
     "phase_scalac_provider",
     "phase_scalacopts",
+    "phase_scalainfo_provider_non_macro",
     "phase_semanticdb",
     "phase_test_environment",
     "phase_write_executable_scalatest",
@@ -38,6 +39,7 @@ def _scala_test_impl(ctx):
         # customizable phases
         [
             ("scalac_provider", phase_scalac_provider),
+            ("scalainfo_provider", phase_scalainfo_provider_non_macro),
             ("write_manifest", phase_write_manifest),
             ("dependency", phase_dependency_common),
             ("collect_jars", phase_collect_jars_scalatest),