Fix build scripts targeting the wrong architecture

.bazelci/presubmit.yml

@@ -366,6 +366,14 @@ tasks:
     working_directory: examples/ios
     build_targets:
       - "//..."
+  ios_build:
+    name: iOS build script cross compile test
+    platform: macos
+    working_directory: examples/ios_build
+    test_flags:
+      - "--platforms=//:ios_x86_64"
+    test_targets:
+      - "//..."
 
 buildifier:
   version: latest

cargo/cargo_build_script.bzl

@@ -13,6 +13,31 @@ load("//rust/private:rustc.bzl", "BuildInfo", "get_compilation_mode_opts", "get_
 # buildifier: disable=bzl-visibility
 load("//rust/private:utils.bzl", "dedent", "expand_dict_value_locations", "find_cc_toolchain", "find_toolchain", "name_to_crate_name")
 
+def strip_target(elems):
+    """Remove '-target xxx' from C(XX)FLAGS.
+
+    The cpp toolchain adds '-target xxx' and '-isysroot xxx' to CFLAGS. If it is not stripped out before
+    the CFLAGS are provided to build scripts, it can cause the build to take on the host architecture
+    instead of the target architecture.
+
+    Args:
+        elems (list): A list of args
+
+    Returns:
+        list: the modified args
+    """
+    skip_next = False
+    out_elems = []
+    for elem in elems:
+        if skip_next:
+            skip_next = False
+            continue
+        if elem == "-target" or elem == "-isysroot":
+            skip_next = True
+            continue
+        out_elems.append(elem)
+    return out_elems
+
 def get_cc_compile_args_and_env(cc_toolchain, feature_configuration):
     """Gather cc environment variables from the given `cc_toolchain`
 
@@ -30,16 +55,16 @@ def get_cc_compile_args_and_env(cc_toolchain, feature_configuration):
         feature_configuration = feature_configuration,
         cc_toolchain = cc_toolchain,
     )
-    cc_c_args = cc_common.get_memory_inefficient_command_line(
+    cc_c_args = strip_target(cc_common.get_memory_inefficient_command_line(
         feature_configuration = feature_configuration,
         action_name = C_COMPILE_ACTION_NAME,
         variables = compile_variables,
-    )
-    cc_cxx_args = cc_common.get_memory_inefficient_command_line(
+    ))
+    cc_cxx_args = strip_target(cc_common.get_memory_inefficient_command_line(
         feature_configuration = feature_configuration,
         action_name = CPP_COMPILE_ACTION_NAME,
         variables = compile_variables,
-    )
+    ))
     cc_env = cc_common.get_environment_variables(
         feature_configuration = feature_configuration,
         action_name = C_COMPILE_ACTION_NAME,

examples/.bazelignore

@@ -2,3 +2,4 @@ android
 cargo_manifest_dir/external_crate
 crate_universe
 ios
+ios_build

examples/ios_build/.gitignore

@@ -0,0 +1 @@
+bazel-*

examples/ios_build/BUILD.bazel

@@ -0,0 +1,65 @@
+load("@rules_rust//rust:defs.bzl", "rust_static_library")
+
+rust_static_library(
+    name = "ios_build_lib",
+    srcs = glob(["**/*.rs"]),
+    edition = "2018",
+    deps = [
+        "@ios_build//:zstd",
+    ],
+)
+
+filegroup(
+    name = "lib",
+    srcs = ["ios_build_lib"],
+)
+
+sh_test(
+    name = "check_arch",
+    srcs = ["check_arch.sh"],
+    args = ["$(location :lib)"],
+    data = [":lib"],
+)
+
+platform(
+    name = "macos_x86_64",
+    constraint_values = [
+        "@platforms//cpu:x86_64",
+        "@platforms//os:macos",
+    ],
+)
+
+platform(
+    name = "macos_arm64",
+    constraint_values = [
+        "@platforms//cpu:arm64",
+        "@platforms//os:macos",
+    ],
+)
+
+platform(
+    name = "ios_x86_64",
+    constraint_values = [
+        "@platforms//cpu:x86_64",
+        "@platforms//os:ios",
+        "@build_bazel_apple_support//constraints:simulator",
+    ],
+)
+
+platform(
+    name = "ios_sim_arm64",
+    constraint_values = [
+        "@platforms//cpu:arm64",
+        "@platforms//os:ios",
+        "@build_bazel_apple_support//constraints:simulator",
+    ],
+)
+
+platform(
+    name = "ios_arm64",
+    constraint_values = [
+        "@platforms//cpu:arm64",
+        "@platforms//os:ios",
+        "@build_bazel_apple_support//constraints:device",
+    ],
+)

examples/ios_build/Cargo.Bazel.lock

@@ -0,0 +1,63 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "cc"
+version = "1.0.73"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2fff2a6927b3bb87f9595d67196a70493f627687a71d87a0d692242c33f58c11"
+dependencies = [
+ "jobserver",
+]
+
+[[package]]
+name = "ios_build"
+version = "0.1.0"
+dependencies = [
+ "zstd",
+]
+
+[[package]]
+name = "jobserver"
+version = "0.1.25"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "068b1ee6743e4d11fb9c6a1e6064b3693a1b600e7f5f5988047d98b3dc9fb90b"
+dependencies = [
+ "libc",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.134"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "329c933548736bc49fd575ee68c89e8be4d260064184389a5b77517cddd99ffb"
+
+[[package]]
+name = "zstd"
+version = "0.11.2+zstd.1.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "20cc960326ece64f010d2d2107537f26dc589a6573a316bd5b1dba685fa5fde4"
+dependencies = [
+ "zstd-safe",
+]
+
+[[package]]
+name = "zstd-safe"
+version = "5.0.2+zstd.1.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1d2a5585e04f9eea4b2a3d1eca508c4dee9592a89ef6f450c11719da0726f4db"
+dependencies = [
+ "libc",
+ "zstd-sys",
+]
+
+[[package]]
+name = "zstd-sys"
+version = "2.0.1+zstd.1.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9fd07cbbc53846d9145dbffdf6dd09a7a0aa52be46741825f5c97bdd4f73f12b"
+dependencies = [
+ "cc",
+ "libc",
+]

examples/ios_build/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "ios_build"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+zstd = "0.11.2"

examples/ios_build/WORKSPACE.bazel

@@ -0,0 +1,64 @@
+workspace(name = "examples")
+
+local_repository(
+    name = "rules_rust",
+    path = "../../",
+)
+
+load("@rules_rust//rust:repositories.bzl", "rules_rust_dependencies", "rust_register_toolchains")
+
+rules_rust_dependencies()
+
+rust_register_toolchains(
+    edition = "2018",
+    extra_target_triples = [
+        "aarch64-apple-ios-sim",
+        "x86_64-apple-ios",
+    ],
+)
+
+load("@rules_rust//crate_universe:repositories.bzl", "crate_universe_dependencies")
+
+crate_universe_dependencies(bootstrap = True)
+
+load("@rules_rust//crate_universe:defs.bzl", "crates_repository", "splicing_config")
+
+crates_repository(
+    name = "ios_build",
+    cargo_lockfile = "//:Cargo.Bazel.lock",
+    # `generator` is not necessary in official releases.
+    # See load satement for `cargo_bazel_bootstrap`.
+    generator = "@cargo_bazel_bootstrap//:cargo-bazel",
+    lockfile = "//:cargo-bazel-lock.json",
+    manifests = ["//:Cargo.toml"],
+    splicing_config = splicing_config(
+        resolver_version = "2",
+    ),
+)
+
+load(
+    "@ios_build//:defs.bzl",
+    ios_build_crate_repositories = "crate_repositories",
+)
+
+ios_build_crate_repositories()
+
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+
+# Used for Bazel CI
+http_archive(
+    name = "bazelci_rules",
+    sha256 = "eca21884e6f66a88c358e580fd67a6b148d30ab57b1680f62a96c00f9bc6a07e",
+    strip_prefix = "bazelci_rules-1.0.0",
+    url = "https://github.com/bazelbuild/continuous-integration/releases/download/rules-1.0.0/bazelci_rules-1.0.0.tar.gz",
+)
+
+load("@bazelci_rules//:rbe_repo.bzl", "rbe_preconfig")
+
+# Creates a default toolchain config for RBE.
+# Use this as is if you are using the rbe_ubuntu16_04 container,
+# otherwise refer to RBE docs.
+rbe_preconfig(
+    name = "buildkite_config",
+    toolchain = "ubuntu1804-bazel-java11",
+)