Fix building for iOS (#767)

examples/WORKSPACE.bazel

@@ -53,3 +53,37 @@ load("@bazel_toolchains//rules:rbe_repo.bzl", "rbe_autoconfig")
 # Use this as is if you are using the rbe_ubuntu16_04 container,
 # otherwise refer to RBE docs.
 rbe_autoconfig(name = "buildkite_config")
+
+http_archive(
+    name = "build_bazel_rules_apple",
+    sha256 = "0052d452af7742c8f3a4e0929763388a66403de363775db7e90adecb2ba4944b",
+    url = "https://github.com/bazelbuild/rules_apple/releases/download/0.31.3/rules_apple.0.31.3.tar.gz",
+)
+
+load(
+    "@build_bazel_rules_apple//apple:repositories.bzl",
+    "apple_rules_dependencies",
+)
+
+apple_rules_dependencies()
+
+load(
+    "@build_bazel_rules_swift//swift:repositories.bzl",
+    "swift_rules_dependencies",
+)
+
+swift_rules_dependencies()
+
+load(
+    "@build_bazel_rules_swift//swift:extras.bzl",
+    "swift_rules_extra_dependencies",
+)
+
+swift_rules_extra_dependencies()
+
+load(
+    "@build_bazel_apple_support//lib:repositories.bzl",
+    "apple_support_dependencies",
+)
+
+apple_support_dependencies()

examples/third_party/BUILD.bazel

@@ -58,6 +58,7 @@ test_suite(
         "//apr:apr_build_test",
         "//apr_util:apr_util_build_test",
         "//cares:test_c_ares",
+        "//cares:test_c_ares_ios",
         "//curl:curl_test_suite",
         "//gn:gn_launch_test",
         "//gperftools:test",

examples/third_party/WORKSPACE.bazel

@@ -17,3 +17,39 @@ local_repository(
 load("//:repositories.bzl", "repositories")
 
 repositories()
+
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+
+http_archive(
+    name = "build_bazel_rules_apple",
+    sha256 = "0052d452af7742c8f3a4e0929763388a66403de363775db7e90adecb2ba4944b",
+    url = "https://github.com/bazelbuild/rules_apple/releases/download/0.31.3/rules_apple.0.31.3.tar.gz",
+)
+
+load(
+    "@build_bazel_rules_apple//apple:repositories.bzl",
+    "apple_rules_dependencies",
+)
+
+apple_rules_dependencies()
+
+load(
+    "@build_bazel_rules_swift//swift:repositories.bzl",
+    "swift_rules_dependencies",
+)
+
+swift_rules_dependencies()
+
+load(
+    "@build_bazel_rules_swift//swift:extras.bzl",
+    "swift_rules_extra_dependencies",
+)
+
+swift_rules_extra_dependencies()
+
+load(
+    "@build_bazel_apple_support//lib:repositories.bzl",
+    "apple_support_dependencies",
+)
+
+apple_support_dependencies()

examples/third_party/cares/BUILD.bazel

@@ -1,8 +1,24 @@
-load("@rules_cc//cc:defs.bzl", "cc_test")
+load("@build_bazel_rules_apple//apple:ios.bzl", "ios_build_test")
+load("@rules_cc//cc:defs.bzl", "cc_library", "cc_test")
 
 cc_test(
     name = "test_c_ares",
     srcs = ["c-ares-test.cpp"],
     visibility = ["//:__pkg__"],
     deps = ["@cares"],
 )
+
+cc_library(
+    name = "ios_lib",
+    srcs = ["c-ares-test.cpp"],
+    tags = ["manual"],
+    deps = ["@cares"],
+)
+
+ios_build_test(
+    name = "test_c_ares_ios",
+    minimum_os_version = "12.0",
+    tags = ["manual"],
+    targets = ["ios_lib"],
+    visibility = ["//:__pkg__"],
+)

foreign_cc/private/framework.bzl

@@ -15,7 +15,6 @@ load(
     "script_extension",
     "shebang",
 )
-load("//foreign_cc/private/framework:platform.bzl", "os_name")
 load(
     ":cc_toolchain_util.bzl",
     "LibrariesToLinkInfo",
@@ -280,15 +279,23 @@ def get_env_prelude(ctx, lib_name, data_dependencies, target_root):
         "export EXT_BUILD_DEPS=$$INSTALLDIR$$.ext_build_deps",
     ]
 
-    if os_name(ctx) == "macos":
-        env_snippet.extend(["export DEVELOPER_DIR=\"$(xcode-select --print-path)\"", "export SDKROOT=\"$(xcrun --sdk macosx --show-sdk-path)\""])
-
     env = dict()
 
     # Add all environment variables from the cc_toolchain
     cc_env = _correct_path_variable(get_env_vars(ctx))
     env.update(cc_env)
 
+    # This logic mirrors XcodeLocalEnvProvider#querySdkRoot in bazel itself
+    if "APPLE_SDK_PLATFORM" in cc_env:
+        platform = cc_env["APPLE_SDK_PLATFORM"]
+        version = cc_env["APPLE_SDK_VERSION_OVERRIDE"]
+        sdk = "{}{}".format(platform.lower(), version)
+        env_snippet.extend([
+            # TODO: This path needs to take cc_env["XCODE_VERSION_OVERRIDE"] into account
+            "export DEVELOPER_DIR=\"$(xcode-select --print-path)\"",
+            "export SDKROOT=\"$(xcrun --sdk {} --show-sdk-path)\"".format(sdk),
+        ])
+
     cc_toolchain = find_cpp_toolchain(ctx)
     if cc_toolchain.compiler == "msvc-cl":
         # Prepend PATH environment variable with the path to the toolchain linker, which prevents MSYS using its linker (/usr/bin/link.exe) rather than the MSVC linker (both are named "link.exe")