Support stripping Swift symbols

[thii]

Description of the problem / feature request:

Support stripping Swift symbols for binaries built for Apple platforms.

Feature requests: what underlying problem are you trying to solve with this feature?

There's currently no option to allow stripping Swift symbols for binaries built for Apple platforms. Since xcodebuild's ipa exporting supports that (and defaults to YES), results in binaries produced by Bazel has a slightly larger size compared to Xcode's.

What operating system are you running Bazel on?

macOS

What's the output of bazel info release?

release 4.0.0

Have you found anything relevant by searching the web?

From the strip man page:

-T
The intent of this flag is to remove Swift symbols. It removes the symbols whose names
begin with `_$S' or `_$s' only when it finds an __objc_imageinfo section with and it has
a non-zero swift version. The future the implementation of this flag may change to match the intent.

From the xcodebuild -h page:

Available keys for -exportOptionsPlist:
        ...
        stripSwiftSymbols : Bool

                Should symbols be stripped from Swift libraries in your IPA? Defaults to YES.

I found two code paths referencing to code stripping but -T is not passed, and passing it via --stripopt doesn't take effect.

bazel/src/main/java/com/google/devtools/build/lib/rules/objc/CompilationSupport.java

Lines 1561 to 1574 in 2576851

	private void registerBinaryStripAction(Artifact binaryToLink, StrippingType strippingType) {
	final ImmutableList<String> stripArgs;
	switch (strippingType) {
	case DYNAMIC_LIB:
	case KERNEL_EXTENSION:
	// For dylibs and kexts, must strip only local symbols.
	stripArgs = ImmutableList.of("-x");
	break;
	case DEFAULT:
	stripArgs = ImmutableList.<String>of();
	break;
	default:
	throw new IllegalArgumentException("Unsupported stripping type " + strippingType);
	}

bazel/tools/osx/crosstool/cc_toolchain_config.bzl

Lines 296 to 311 in ef903e0

	strip_action = action_config(
	action_name = ACTION_NAMES.strip,
	flag_sets = [
	flag_set(
	flag_groups = [
	flag_group(flags = ["-S", "-o", "%{output_file}"]),
	flag_group(
	flags = ["%{stripopts}"],
	iterate_over = "stripopts",
	),
	flag_group(flags = ["%{input_file}"]),
	],
	),
	],
	tools = [tool(path = "/usr/bin/strip")],
	)

[jin]

@susinmotion how should we route ObjC rules issues like this one?

[keith]

#13123

[susinmotion]

@jin you did exactly the right thing!

[github-actions]

Thank you for contributing to the Bazel repository! This issue has been marked as stale since it has not had any activity in the last 1+ years. It will be closed in the next 14 days unless any other activity occurs or one of the following labels is added: "not stale", "awaiting-bazeler". Please reach out to the triage team (@bazelbuild/triage) if you think this issue is still relevant or you are interested in getting the issue resolved.