Add generate_linkmap attribute support

Author: brentleyjones

apple/internal/linking_support.bzl

@@ -298,7 +298,7 @@ def _link_multi_arch_binary(
             legacy_debug_outputs.setdefault(platform_info.target_arch, {})["dsym_binary"] = dsym_binary
 
         linkmap = None
-        if ctx.fragments.cpp.objc_generate_linkmap:
+        if ctx.attr.generate_linkmap or ctx.fragments.cpp.objc_generate_linkmap:
             linkmap = intermediates.file(
                 actions = ctx.actions,
                 target_name = ctx.label.name,
@@ -371,7 +371,8 @@ def _debug_outputs_by_architecture(link_outputs):
 
     for link_output in link_outputs:
         dsym_binaries[link_output.architecture] = link_output.dsym_binary
-        linkmaps[link_output.architecture] = link_output.linkmap
+        if link_output.linkmap:
+            linkmaps[link_output.architecture] = link_output.linkmap
 
     return struct(
         dsym_binaries = dsym_binaries,
@@ -548,13 +549,17 @@ def _register_binary_linking_action(
         linkopts.extend(["-bundle_loader", bundle_loader_file.path])
         link_inputs.append(bundle_loader_file)
 
+    requested_features = list(extra_requested_features)
+    if ctx.attr.generate_linkmap or ctx.fragments.cpp.objc_generate_linkmap:
+        requested_features.append("generate_linkmap")
+
     linking_outputs = _link_multi_arch_binary(
         ctx = ctx,
         avoid_deps = all_avoid_deps,
         cc_toolchains = cc_toolchains,
         extra_linkopts = linkopts,
         extra_link_inputs = link_inputs,
-        extra_requested_features = extra_requested_features,
+        extra_requested_features = requested_features,
         # TODO(321109350): Disable include scanning to work around issue with GrepIncludes actions
         # being routed to the wrong exec platform.
         extra_disabled_features = extra_disabled_features + ["cc_include_scanning"],

apple/internal/partials/debug_symbols.bzl

@@ -433,7 +433,7 @@ def _debug_symbols_partial_impl(
                 direct_dsym_bundles.append(dsym_bundle_dir)
             direct_dsyms.extend(dsym_files)
 
-        if platform_prerequisites.cpp_fragment.objc_generate_linkmap:
+        if linkmaps:
             linkmaps = _collect_linkmaps(
                 actions = actions,
                 debug_output_filename = debug_output_filename,

apple/internal/providers/apple_debug_info.bzl

@@ -26,7 +26,7 @@ partial and the resource aspect.
 Depset of `File` references to dSYM files if requested in the build with --apple_generate_dsym.
 """,
         "linkmaps": """
-Depset of `File` references to linkmap files if requested in the build with --objc_generate_linkmap.
+Depset of `File` references to linkmap files when linkmap generation is requested.
 """,
     },
 )

apple/internal/rule_attrs.bzl

@@ -213,6 +213,15 @@ were marked as `__private_extern__` (aka `visibility=hidden`) and will not be gl
 file.
 
 See the man page documentation for `ld(1)` on macOS for more details.
+""",
+            ),
+            "generate_linkmap": attr.bool(
+                default = False,
+                doc = """
+Whether to generate a linkmap file for this target's linked binary.
+
+This attribute augments `--objc_generate_linkmap`; if the command-line flag is set, a linkmap is
+still generated even when this attribute is `False`.
 """,
             ),
             "linkopts": attr.string_list(

doc/common_info.md

@@ -34,8 +34,9 @@ which files are requested:
 *   `linkmaps`: This output group contains all linkmap files generated during
     the build, for the top level target **and** its embedded dependencies. To
     request this output group to be built, use the `--output_groups=+linkmaps`
-    flag. In order to generate the linkmap files you still need to pass the
-    `--objc_generate_linkmap` flag.
+    flag. Linkmap generation can be requested either per-target with the
+    `generate_linkmap` attribute or globally with the `--objc_generate_linkmap`
+    flag.
 
 ### dSYMs Generation {#apple_generate_dsym}
 
@@ -116,12 +117,23 @@ flags yourself.
 
 Linkmaps can be useful for figuring out how the `deps` going into a target are
 contributing to the final size of the binary. Bazel will generate a link map
-when linking by adding `--objc_generate_linkmap` to a `bazel build`.
+when linking if either the rule's `generate_linkmap` attribute is `True` or
+`--objc_generate_linkmap` is added to a `bazel build`.
 
 ```shell
 bazel build --objc_generate_linkmap //your/target
 ```
 
+Or:
+
+```bzl
+ios_application(
+    name = "app",
+    generate_linkmap = True,
+    # ...
+)
+```
+
 By default, only the top level linkmap file is built when this flag is
 specified. If you require the linkmap file of the top level target dependencies,
 you'll need to specify the `--output_groups=+linkmaps` flag.

test/starlark_tests/ios_application_tests.bzl

@@ -32,6 +32,7 @@ load(
 )
 load(
     "//test/starlark_tests/rules:analysis_output_group_info_files_test.bzl",
+    "analysis_output_group_info_files_attr_test",
     "analysis_output_group_info_files_test",
 )
 load(
@@ -71,6 +72,7 @@ load(
 )
 load(
     "//test/starlark_tests/rules:linkmap_test.bzl",
+    "linkmap_attr_test",
     "linkmap_test",
 )
 load(
@@ -1009,6 +1011,32 @@ def ios_application_test_suite(name):
         ],
         tags = [name],
     )
+    linkmap_attr_test(
+        name = "{}_generate_linkmap_attr_test".format(name),
+        target_under_test = "//test/starlark_tests/targets_under_test/ios:app_with_generate_linkmap",
+        expected_linkmap_names = ["app_with_generate_linkmap"],
+        tags = [name],
+    )
+    analysis_output_group_info_files_attr_test(
+        name = "{}_generate_linkmap_attr_output_group_info_test".format(name),
+        target_under_test = "//test/starlark_tests/targets_under_test/ios:app_with_generate_linkmap",
+        output_group_name = "linkmaps",
+        expected_outputs = [
+            "app_with_generate_linkmap_x86_64.linkmap",
+            "app_with_generate_linkmap_arm64.linkmap",
+        ],
+        tags = [name],
+    )
+    action_command_line_test(
+        name = "{}_generate_linkmap_attr_link_action_test".format(name),
+        target_under_test = "//test/starlark_tests/targets_under_test/ios:app_with_generate_linkmap",
+        mnemonic = "ObjcLink",
+        expected_argv = [
+            "-Xlinker -map",
+            "app_with_generate_linkmap.linkmap",
+        ],
+        tags = [name],
+    )
 
     # Test that Bitcode was removed from the imported framework when building
     # with Bitcode disabled.

test/starlark_tests/rules/analysis_output_group_info_files_test.bzl

@@ -72,3 +72,7 @@ def make_analysis_output_group_info_files_test(config_settings = {}):
     )
 
 analysis_output_group_info_files_test = make_analysis_output_group_info_files_test()
+
+analysis_output_group_info_files_attr_test = make_analysis_output_group_info_files_test(
+    config_settings = {},
+)

test/starlark_tests/rules/linkmap_test.bzl

@@ -64,33 +64,41 @@ def _linkmap_test_impl(ctx):
 
     return analysistest.end(env)
 
-linkmap_test = analysistest.make(
-    _linkmap_test_impl,
-    attrs = {
-        "architectures": attr.string_list(
-            mandatory = False,
-            default = [],
-            doc = """
+def make_linkmap_test(config_settings = {}):
+    return analysistest.make(
+        _linkmap_test_impl,
+        attrs = {
+            "architectures": attr.string_list(
+                mandatory = False,
+                default = [],
+                doc = """
 List of architectures to verify for the given dSYM bundles as provided. Defaults to x86_64 for all
 platforms.
 """,
-        ),
-        "expected_linkmap_names": attr.string_list(
-            mandatory = False,
-            default = [],
-            doc = """
+            ),
+            "expected_linkmap_names": attr.string_list(
+                mandatory = False,
+                default = [],
+                doc = """
 List of linkmap names to verify that linkmaps are created. Defaults to the target name if none is
 provided.
 """,
-        ),
-    },
+            ),
+        },
+        config_settings = {
+            "//command_line_option:macos_cpus": "arm64,x86_64",
+            "//command_line_option:ios_multi_cpus": "sim_arm64,x86_64",
+            "//command_line_option:tvos_cpus": "sim_arm64,x86_64",
+            "//command_line_option:visionos_cpus": "sim_arm64",
+            "//command_line_option:watchos_cpus": "arm64,x86_64",
+        } | config_settings,
+        fragments = ["apple"],
+    )
+
+linkmap_test = make_linkmap_test(
     config_settings = {
         "//command_line_option:objc_generate_linkmap": "true",
-        "//command_line_option:macos_cpus": "arm64,x86_64",
-        "//command_line_option:ios_multi_cpus": "sim_arm64,x86_64",
-        "//command_line_option:tvos_cpus": "sim_arm64,x86_64",
-        "//command_line_option:visionos_cpus": "sim_arm64",
-        "//command_line_option:watchos_cpus": "arm64,x86_64",
     },
-    fragments = ["apple"],
 )
+
+linkmap_attr_test = make_linkmap_test()

test/starlark_tests/targets_under_test/ios/BUILD

@@ -482,6 +482,43 @@ ios_application(
     ],
 )
 
+ios_application(
+    name = "app_with_generate_linkmap",
+    app_icons = ["//test/testdata/resources:app_icons_ios"],
+    bundle_id = "com.google.example",
+    entitlements = "//test/starlark_tests/resources:entitlements.plist",
+    families = ["iphone"],
+    generate_linkmap = True,
+    infoplists = [
+        "//test/starlark_tests/resources:Info.plist",
+    ],
+    launch_storyboard = "//test/starlark_tests/resources:launch_screen_ios.storyboard",
+    minimum_os_version = common.min_os_ios.baseline,
+    provisioning_profile = "//test/testdata/provisioning:integration_testing_ios.mobileprovision",
+    resources = [
+        "//test/starlark_tests/resources:example_filegroup",
+        "//test/starlark_tests/resources:localization",
+        "//test/starlark_tests/resources:resource_bundle",
+    ],
+    settings_bundle = "//test/starlark_tests/resources:settings_bundle_ios",
+    tags = common.fixture_tags,
+    visibility = [
+        "//test/starlark_tests:__subpackages__",
+        "//tools/dossier_codesigningtool:__pkg__",
+    ],
+    deps = [
+        "//test/starlark_tests/resources:basic_bundle_lib",
+        "//test/starlark_tests/resources:bundle_library_ios_lib",
+        "//test/starlark_tests/resources:empty_strings_file_lib",
+        "//test/starlark_tests/resources:ios_localized_assets_lib",
+        "//test/starlark_tests/resources:ios_non_localized_assets_lib",
+        "//test/starlark_tests/resources:nested_bundle_lib",
+        "//test/starlark_tests/resources:objc_linkopt_lib",
+        "//test/starlark_tests/resources:objc_main_lib",
+        "//test/starlark_tests/resources:sticker_pack_ios_lib",
+    ],
+)
+
 ios_application(
     name = "app_with_bundle_library_dependency",
     bundle_id = "com.google.example",