Whats the equivalent of ${ANDROID_ABI} when linking static lib in Bazel?

Issue

In cmake you can specify ${ANDROID_ABI} when linking a static C++ lib to get the correct version of the library (e.g. arm64-v8a, armeabi-v7a, x86_64, etc)

target_link_libraries(mylib debug
        foo/lib/${ANDROID_ABI}/libfoo.a

What's the equivalent of that in Bazel? If I have platform specific versions of libfoo.a in foo/lib/arm64-v8a, foo/lib/arm64-v8a, foo/lib/arm64-v8a, etc. How do I link the correct on in Bazel?

Solution

You can use select(), config_setting, and --fat_apk_cpu for this:

cc_library(
  name = "foo",
  srcs = select({
    "arm64-v8a": ["foo/lib/arm64-v8a/libfoo.a"],
    "armeabi-v7a": ["foo/lib/armeabi-v7a/libfoo.a"],
    "x86": ["foo/lib/x86/libfoo.a"],
    "x86_64": ["foo/lib/x86_64/libfoo.a"],
  }),
)

config_setting(
  name = "arm64-v8a",
  values = {
    "cpu": "arm64-v8a",
  },
)

config_setting(
  name = "armeabi-v7a",
  values = {
    "cpu": "armeabi-v7a",
  },
)

config_setting(
  name = "x86",
  values = {
    "cpu": "x86",
  },
)

config_setting(
  name = "x86_64",
  values = {
    "cpu": "x86_64",
  },
)

and your cc_library rules can depend on foo.

Then specify --fat_apk_cpu on the command line, e.g. to build and package a .so for each platform, specify --fat_apk_cpu=arm64-v8a,armeabi-v7a,x86,x86_64, or some subset for what you're targeting, e.g. for an emulator --fat_apk_cpu=x86_64

Answered By - ahumesky