Flip the default fallback value for _building_apple_bundle to True, and manually set it to False for rules that don't bundle.

This ensures that other users of our transitions on custom rules share any actions/configurations with the targets when they are nested under a bundle (the common case for users of the Apple transitions).

Cherry-pick: c8de42c

Author: allevato

apple/internal/apple_universal_binary.bzl

@@ -105,6 +105,13 @@ binary will be built for all of the specified architectures instead.
 This is primarily useful to force macOS tools to be built as universal binaries using
 `forced_cpus = ["x86_64", "arm64"]`, without requiring the user to pass additional flags when
 invoking Bazel.
+""",
+            ),
+            "_building_apple_bundle": attr.bool(
+                default = False,
+                doc = """
+Internal attribute read by Apple rule transitions to set the
+`building_apple_bundle` build setting.
 """,
             ),
         },

apple/internal/macos_rules.bzl

@@ -2704,6 +2704,7 @@ Targets created with `macos_command_line_application` can be executed using
                 apple_resource_aspect,
                 framework_provider_aspect,
             ],
+            is_bundling_rule = False,
             is_test_supporting_rule = False,
             requires_legacy_cc_toolchain = True,
         ),
@@ -2760,6 +2761,7 @@ macos_dylib = rule_factory.create_apple_rule(
                 apple_resource_aspect,
                 framework_provider_aspect,
             ],
+            is_bundling_rule = False,
             is_test_supporting_rule = False,
             requires_legacy_cc_toolchain = True,
         ),

apple/internal/rule_attrs.bzl

@@ -147,6 +147,7 @@ def _binary_linking_attrs(
         *,
         deps_cfg,
         extra_deps_aspects = [],
+        is_bundling_rule = True,
         is_test_supporting_rule,
         requires_legacy_cc_toolchain):
     """Returns dictionary of required attributes for apple_common.link_multi_arch_binary.
@@ -157,6 +158,9 @@ def _binary_linking_attrs(
             use the same transition.
         extra_deps_aspects: A list of aspects to apply to deps in addition to the defaults.
             Optional.
+        is_bundling_rule: Boolean. Indicates if the binary being linked will be placed inside an
+            Apple bundle target (as opposed to a standalone binary, like a command line application
+            or dylib).
         is_test_supporting_rule: Boolean. Indicates if this rule is intended to be used as a
             dependency of a test rule, such as a test bundle rule generated by an ios_unit_test
             macro.
@@ -169,6 +173,20 @@ def _binary_linking_attrs(
     deps_aspects.extend(extra_deps_aspects)
     extra_attrs = {}
 
+    if not is_bundling_rule:
+        # For bundling rules, the `_building_apple_bundle` attribute will be
+        # provided by `common_bundle_attrs`. We require adding it manually for
+        # non-bundling rules so that they can override the fallback value of
+        # `True` used by the transition (which is needed to prevent spikes in
+        # configuration/action counts for other users of the transitions).
+        extra_attrs["_building_apple_bundle"] = attr.bool(
+            default = False,
+            doc = """
+Internal attribute read by Apple rule transitions to set the
+`building_apple_bundle` build setting.
+""",
+        )
+
     default_stamp = -1
     if is_test_supporting_rule:
         deps_aspects.append(apple_test_info_aspect)

apple/internal/transition_support.bzl

@@ -304,7 +304,7 @@ def _is_arch_supported_for_target_tuple(*, environment_arch, minimum_os_version,
 def _command_line_options(
         *,
         apple_platforms = [],
-        building_apple_bundle = False,
+        building_apple_bundle,
         environment_arch = None,
         force_bundle_outputs = False,
         minimum_os_version,
@@ -475,7 +475,7 @@ def _apple_rule_base_transition_impl(settings, attr):
     """Rule transition for Apple rules using Bazel CPUs and a valid Apple split transition."""
     minimum_os_version = attr.minimum_os_version
     platform_type = attr.platform_type
-    building_apple_bundle = getattr(attr, "_building_apple_bundle", False)
+    building_apple_bundle = getattr(attr, "_building_apple_bundle", True)
     return _command_line_options(
         building_apple_bundle = building_apple_bundle,
         environment_arch = _environment_archs(platform_type, minimum_os_version, settings)[0],
@@ -539,7 +539,7 @@ def _apple_platforms_rule_base_transition_impl(settings, attr):
     """Rule transition for Apple rules using Bazel platforms and the Starlark split transition."""
     minimum_os_version = attr.minimum_os_version
     platform_type = attr.platform_type
-    building_apple_bundle = getattr(attr, "_building_apple_bundle", False)
+    building_apple_bundle = getattr(attr, "_building_apple_bundle", True)
     environment_arch = None
     if not settings["//command_line_option:incompatible_enable_apple_toolchain_resolution"]:
         # Add fallback to match an anticipated split of Apple cpu-based resolution
@@ -563,7 +563,7 @@ def _apple_platforms_rule_bundle_output_base_transition_impl(settings, attr):
     """Rule transition for Apple rules using Bazel platforms which force bundle outputs."""
     minimum_os_version = attr.minimum_os_version
     platform_type = attr.platform_type
-    building_apple_bundle = getattr(attr, "_building_apple_bundle", False)
+    building_apple_bundle = getattr(attr, "_building_apple_bundle", True)
     environment_arch = None
     if not settings["//command_line_option:incompatible_enable_apple_toolchain_resolution"]:
         # Add fallback to match an anticipated split of Apple cpu-based resolution
@@ -671,7 +671,7 @@ def _apple_platform_split_transition_impl(settings, attr):
             if str(platform) not in output_dictionary:
                 output_dictionary[str(platform)] = _command_line_options(
                     apple_platforms = apple_platforms,
-                    building_apple_bundle = getattr(attr, "_building_apple_bundle", False),
+                    building_apple_bundle = getattr(attr, "_building_apple_bundle", True),
                     minimum_os_version = attr.minimum_os_version,
                     platform_type = attr.platform_type,
                     settings = settings,
@@ -680,7 +680,7 @@ def _apple_platform_split_transition_impl(settings, attr):
     else:
         minimum_os_version = attr.minimum_os_version
         platform_type = attr.platform_type
-        building_apple_bundle = getattr(attr, "_building_apple_bundle", False)
+        building_apple_bundle = getattr(attr, "_building_apple_bundle", True)
         for environment_arch in _environment_archs(platform_type, minimum_os_version, settings):
             found_cpu = _cpu_string(
                 environment_arch = environment_arch,
@@ -759,6 +759,7 @@ def _xcframework_base_transition_impl(settings, _):
     # incoming settings meant for other platforms overriding the settings for the xcframework rule's
     # underlying actions, and allow for toolchain resolution in the future.
     return _command_line_options(
+        building_apple_bundle = False,
         environment_arch = _DEFAULT_ARCH,
         minimum_os_version = None,
         platform_type = "macos",
@@ -790,7 +791,7 @@ def _xcframework_split_transition_impl(settings, attr):
             target_environments.append("simulator")
 
         command_line_options = _command_line_options_for_xcframework_platform(
-            building_apple_bundle = getattr(attr, "_building_apple_bundle", False),
+            building_apple_bundle = getattr(attr, "_building_apple_bundle", True),
             minimum_os_version = attr.minimum_os_versions.get(platform_type),
             platform_attr = platform_attr,
             platform_type = platform_type,