feat(bazel): ng_module produces bundle index (#22176)

It creates the bundle index .d.ts and .metadata.json files.
The names are based on the ng_module target.

PR Close #22176

packages/bazel/src/BUILD.bazel

@@ -1 +1,31 @@
-# Empty marker file, indicating this directory is a Bazel package.
+package(default_visibility = ["//visibility:public"])
+
+load("@build_bazel_rules_nodejs//:defs.bzl", "nodejs_binary")
+
+nodejs_binary(
+    name = "rollup_with_build_optimizer",
+    data = ["@angular_devkit//packages/angular_devkit/build_optimizer:lib"],
+    # Since our rule extends the one in rules_nodejs, we use the same runtime
+    # dependency @build_bazel_rules_nodejs_rollup_deps. We don't need any
+    # additional npm dependencies when we run rollup or uglify.
+    entry_point = "build_bazel_rules_nodejs_rollup_deps/node_modules/rollup/bin/rollup",
+    node_modules = "@build_bazel_rules_nodejs_rollup_deps//:node_modules",
+)
+
+nodejs_binary(
+    name = "modify_tsconfig",
+    data = ["modify_tsconfig.js"],
+    entry_point = "angular/packages/bazel/src/modify_tsconfig.js",
+)
+
+nodejs_binary(
+    name = "index_bundler",
+    data = [
+        # BEGIN-INTERNAL
+        # Only needed when compiling within the Angular repo.
+        # Users will get this dependency from node_modules.
+        "//packages/compiler-cli",
+        # END-INTERNAL
+    ],
+    entry_point = "@angular/compiler-cli/src/metadata/bundle_index_main.js",
+)

packages/bazel/src/ng_module.bzl

@@ -12,6 +12,7 @@ load(":rules_typescript.bzl",
     "compile_ts",
     "DEPS_ASPECTS",
     "ts_providers_dict_to_struct",
+    "json_marshal",
 )
 
 # Calculate the expected output of the template compiler for every source in
@@ -220,6 +221,43 @@ def _ts_expected_outs(ctx, label):
   _ignored = [label]
   return _expected_outs(ctx)
 
+def _write_bundle_index(ctx):
+  basename = "_%s.bundle_index" % ctx.label.name
+  tsconfig_file = ctx.actions.declare_file("%s.tsconfig.json" % basename)
+  metadata_file = ctx.actions.declare_file("%s.metadata.json" % basename)
+  tstyping_file = ctx.actions.declare_file("%s.d.ts" % basename)
+
+  tsconfig = dict(tsc_wrapped_tsconfig(ctx, ctx.files.srcs, ctx.files.srcs), **{
+    "angularCompilerOptions": {
+      "flatModuleOutFile": basename,
+    },
+  })
+  if ctx.attr.module_name:
+    tsconfig["angularCompilerOptions"]["flatModuleId"] = ctx.attr.module_name
+
+  # createBundleIndexHost in bundle_index_host.ts will throw if the "files" has more than one entry.
+  # We don't want to fail() here, however, because not all ng_module's will have the bundle index written.
+  # So we make the assumption that the index.ts file in the highest parent directory is the entry point.
+  index_file = None
+  for f in tsconfig["files"]:
+    if f.endswith("/index.ts"):
+      if not index_file or len(f) < len(index_file):
+        index_file = f
+  tsconfig["files"] = [index_file]
+
+  ctx.actions.write(tsconfig_file, json_marshal(tsconfig))
+
+  outputs = [metadata_file, tstyping_file]
+
+  ctx.action(
+      progress_message = "Producing metadata for bundle %s" % ctx.label.name,
+      executable = ctx.executable._index_bundler,
+      inputs = ctx.files.srcs + [tsconfig_file],
+      outputs = outputs,
+      arguments = ["-p", tsconfig_file.path],
+  )
+  return outputs
+
 def ng_module_impl(ctx, ts_compile_actions):
   """Implementation function for the ng_module rule.
 
@@ -247,6 +285,13 @@ def ng_module_impl(ctx, ts_compile_actions):
   }
   providers["ngc_messages"] = outs.i18n_messages
 
+  # Only produces the flattened "index bundle" metadata when requested by some other rule
+  # and only under Bazel
+  if hasattr(ctx.executable, "_index_bundler"):
+    bundle_index_metadata = _write_bundle_index(ctx)
+    # note, not recursive
+    providers["angular"]["flat_module_metadata"] = depset(bundle_index_metadata)
+
   return providers
 
 def _ng_module_impl(ctx):
@@ -291,6 +336,10 @@ ng_module = rule(
         "node_modules": attr.label(
             default = Label("@//:node_modules")
         ),
+        "_index_bundler": attr.label(
+            executable = True,
+            cfg = "host",
+            default = Label("//packages/bazel/src:index_bundler")),
     }),
     outputs = COMMON_OUTPUTS,
 )