Description
Hello,
I need to apply a transition on a target defined by ios_extension rule.
I have the following setup:
App -> Extension
App -> Module_A -> Module_B -> Module_C -> ... -> Module_Z
Extension -> Module_B -> Module_C
- Modules are statically linked into top level targets:
App,Extension. Module_Cis the largest module.
In order to reduce App size, i would like to flavour Module_C for Extension.
In order to flavour Module_C for Extension i need to propagate a custom build setting along the Extension -> ... dependency tree.
I have done some research and it looks like that at the moment there is no supported way of applying a transition on a target defined by a third party rule.
The most commonly proposed workaround that i found is to create a wrapper rule around the third party rule.
The wrapper rule can apply required transitions on the wrapped rule and propagate its providers.
I have pretty much done this with ios_extension, but there is an issue that i am facing.
The issue is that not all ios_extension's providers are accessible from outside of rules_apple, and without for example AppleDebugInfo no dSYMs for Extension are generated, or without _AppleSymbolsFileInfo no .symbols for Extension are generated.
I didn't find any difference in the output with/without _AppleCodesigningDossierInfo, AppleExtensionSafeValidationInfo, _AppleSwiftDylibsInfo.
load("//Bazel/flavour:flavour_transition.bzl", "flavour_transition")
load(
"@build_bazel_rules_apple//apple:providers.bzl",
"AppleBundleInfo",
"AppleCodesigningDossierInfo",
"AppleDsymBundleInfo",
"AppleResourceInfo",
"IosExtensionBundleInfo",
)
load(
"@build_bazel_rules_apple//apple/internal/providers:embeddable_info.bzl",
"AppleEmbeddableInfo",
)
def _flavoured_ios_extension_impl(ctx):
ios_extension = ctx.attr.ios_extension[0]
# The list of providers extracted from the `print(ios_extension)` output (unaccessible providers are commented out).
ios_extension_providers = [
DefaultInfo,
apple_common.AppleExecutableBinary,
IosExtensionBundleInfo,
apple_common.AppleDebugOutputs,
AppleBundleInfo,
# _AppleCodesigningDossierInfo,
AppleCodesigningDossierInfo,
AppleDsymBundleInfo,
# AppleDebugInfo,
AppleEmbeddableInfo,
# _AppleExtensionSafeValidationInfo,
AppleResourceInfo,
# _AppleSwiftDylibsInfo,
# _AppleSymbolsFileInfo,
OutputGroupInfo,
]
return [
ios_extension[provider]
for provider in ios_extension_providers
if provider in ios_extension
]
flavoured_ios_extension = rule(
implementation = _flavoured_ios_extension_impl,
doc = "ios_extension wrapper that applies flavour_transition",
attrs = {
"ios_extension": attr.label(mandatory = True, cfg = flavour_transition),
"flavour": attr.string(mandatory = True),
"_allowlist_function_transition": attr.label(default = "@bazel_tools//tools/allowlists/function_transition_allowlist"),
},
)