Prepare databinding integration for moving the DatabindingV2Provider …

…attributes class_infos and setter_stores from lists to depsets.

See
bazelbuild/bazel@876d48d
bazelbuild/bazel#11497 (comment)
bazelbuild/bazel#12780

rules/data_binding.bzl

@@ -66,15 +66,27 @@ def _gen_sources(ctx, output_dir, java_package, deps, layout_info, data_binding_
     args.add("-zipSourceOutput", "true")
     args.add("-useAndroidX", "false")
 
-    class_infos = []
-    for info in deps:
-        class_infos.extend(info.class_infos)
+    if deps:
+        if type(deps[0].class_infos) == "depset":
+            class_infos = depset(transitive = [info.class_infos for info in deps])
+            inputs = depset(direct = [layout_info], transitive = [class_infos])
+        elif type(deps[0].class_infos) == "list":
+            class_infos = []
+            for info in deps:
+                class_infos.extend(info.class_infos)
+            inputs = class_infos + [layout_info]
+        else:
+            fail("Expected list or depset. Got %s" % type(deps[0].class_infos))
+    else:
+        class_infos = []
+        inputs = [layout_info]
+
     args.add_all(class_infos, before_each = "-dependencyClassInfoList")
 
     ctx.actions.run(
         executable = data_binding_exec,
         arguments = ["GEN_BASE_CLASSES", args],
-        inputs = class_infos + [layout_info],
+        inputs = inputs,
         outputs = [class_info, srcjar],
         mnemonic = "GenerateDataBindingBaseClasses",
         progress_message = (
@@ -91,8 +103,8 @@ def _setup_dependent_lib_artifacts(ctx, output_dir, deps):
     for info in deps:
         # Yes, DataBinding requires depsets iterations.
         for artifact in (info.transitive_br_files.to_list() +
-                         info.setter_stores +
-                         info.class_infos):
+                         _utils.list_or_depset_to_list(info.setter_stores) +
+                         _utils.list_or_depset_to_list(info.class_infos)):
             # short_path might contain a parent directory reference if the
             # databinding artifact is from an external repository (e.g. an aar
             # from Maven). If that's the case, just remove the parent directory

rules/utils.bzl

@@ -195,6 +195,14 @@ def _only(collection):
         _error("Expected one element, has %s." % len(collection))
     return _first(collection)
 
+def _list_or_depset_to_list(list_or_depset):
+    if type(list_or_depset) == "list":
+        return list_or_depset
+    elif type(list_or_depset) == "depset":
+        return list_or_depset.to_list()
+    else:
+        return _error("Expected a list or a depset. Got %s" % type(list_or_depset))
+
 def _copy_file(ctx, src, dest):
     if src.is_directory or dest.is_directory:
         fail("Cannot use copy_file with directories")
@@ -444,6 +452,7 @@ utils = struct(
     sanitize_string = _sanitize_string,
     sanitize_java_package = _sanitize_java_package,
     hex = _hex,
+    list_or_depset_to_list = _list_or_depset_to_list,
 )
 
 log = struct(