joltc-sys: native iOS cross-compile (stacked on #12)#13
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Two coupled bugs surfaced when cross-compiling joltc-sys to
Android (aarch64-linux-android via NDK r26d clang from a Windows
host):
1. `cfg!(windows)` is a HOST-OS check inside build.rs. When
targeting Android from Windows, the conditional always fires
and adds the MSVC-only `/EHsc` flag to the cmake config — NDK
clang then receives `/EHsc` as a path argument and errors out
("error: no such file or directory: '/EHsc'").
Fix: read `CARGO_CFG_TARGET_OS` and only add `/EHsc` when the
actual target is windows.
2. Building for Android requires three CMake-side hints that
joltc-sys does not currently set: `CMAKE_TOOLCHAIN_FILE`
(NDK's `android.toolchain.cmake`), `ANDROID_ABI` (string the
toolchain reads — env var alone is ignored), and the
generator (Ninja, since cmake-rs defaults to MSBuild on
Windows hosts).
Fix: when `target_os == "android"`, derive ANDROID_ABI from
`CARGO_CFG_TARGET_ARCH` (aarch64 → arm64-v8a, arm →
armeabi-v7a, etc.), look up the NDK at
`ANDROID_NDK_HOME` / `ANDROID_NDK_ROOT` / `ANDROID_NDK`,
and force Ninja.
End-user contract after this change: set ANDROID_NDK_HOME,
run `cargo ndk --target aarch64-linux-android check -p joltc-sys`.
The standard cargo-ndk + nttld/setup-ndk@v1 flow Just Works.
Validated locally on Windows-host → aarch64-linux-android with
NDK r26d (full JoltPhysics + JoltC compiles in ~20s). 32-bit ARM
(armv7-linux-androideabi) hits an unrelated upstream JoltC
LAYOUT_COMPATIBLE static_assert (`JPC_*Settings` 16-byte
alignment vs `JPH::*Settings` 8-byte alignment on 32-bit ARM)
that this PR does not address.
Adds an iOS branch alongside the Android branch from SecondHalfGames#12. Covers both `aarch64-apple-ios` (device) and `aarch64-apple-ios-sim` (simulator on Apple Silicon hosts); `x86_64-apple-ios` is the legacy Intel-Mac simulator path. From a macOS host: ```sh cargo check --target aarch64-apple-ios -p joltc-sys cargo check --target aarch64-apple-ios-sim -p joltc-sys ``` Both succeed with no extra env-var setup. ## Two coupled fixes 1. **`build_joltc()` iOS branch.** Sets `CMAKE_SYSTEM_NAME=iOS`, `CMAKE_OSX_SYSROOT` (`iphoneos` for device vs `iphonesimulator` for simulator, distinguished via `CARGO_CFG_TARGET_ABI=sim`), `CMAKE_OSX_ARCHITECTURES` from `target_arch`, and `CMAKE_OSX_DEPLOYMENT_TARGET=12.0`. Forces Ninja so the build is generator-agnostic on macos CI runners. 2. **`generate_bindings()` clang-target translation.** bindgen passes rustc's TARGET to clang verbatim. rustc's iOS-simulator triple `aarch64-apple-ios-sim` is invalid clang syntax — clang errors with `version 'sim' in target triple is invalid`. Translate to clang's recognised form (`arm64-apple-ios-simulator` for sim, `arm64-apple-ios` for device) and supply the matching SDK sysroot via `xcrun --show-sdk-path` so iOS system headers (stdint.h, etc.) resolve. ## Validation - `cargo check --target aarch64-apple-ios -p joltc-sys` on macOS host (Xcode 16.4, iPhoneOS 18.5 SDK): succeeds. - `cargo check --target aarch64-apple-ios-sim -p joltc-sys`: succeeds. - Downstream Titan engine's `titan-jolt-3d` builds against both iOS targets in CI on `macos-latest`. - Desktop targets unaffected (iOS branch gated on `target_os == "ios"`). ## Stacking note This PR is stacked on SecondHalfGames#12 (`android-cross-compile-and-target-os-fix`) to share the host-vs-target awareness scaffolding. Either PR can merge first — the iOS branch is a strict additive layer.
3 tasks
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Stacked on #12 — adds an iOS branch alongside the Android branch covered there. From a macOS host:
Both succeed with no extra env-var setup.
Problem
Without an iOS branch in
joltc-sys/build.rs, the standard cargo iOS cross-compile flow fails in two distinct places:1. CMake builds against the macOS SDK
cmake-rs picks the macOS SDK by default on a macOS host. The resulting static libs link against macOS-only symbols and fail at the rust-side link step with
undefined symbolfor every iOS-specific runtime entry point. Need to setCMAKE_SYSTEM_NAME=iOS+CMAKE_OSX_SYSROOT(iphoneosfor device vsiphonesimulatorfor simulator) +CMAKE_OSX_ARCHITECTURES+CMAKE_OSX_DEPLOYMENT_TARGET.Cargo distinguishes the simulator at the target-triple level via
CARGO_CFG_TARGET_ABI=sim—aarch64-apple-ios-simsets it,aarch64-apple-iosdoesn't. Mirror that on the CMake side.2. bindgen passes rustc's TARGET to clang verbatim
rustc's iOS-simulator triple
aarch64-apple-ios-simis invalid clang syntax — clang errors withversion 'sim' in target triple is invalid. Translate to clang's recognised form (arm64-apple-ios-simulatorfor sim,arm64-apple-iosfor device) and supply the matching SDK sysroot viaxcrun --show-sdk-pathso iOS system headers (stdint.h, etc.) resolve correctly.Fix
Two coupled additions:
build_joltc()iOS branch. Sets the four CMake variables above; forces Ninja so the build is generator-agnostic on macos CI runners.generate_bindings()clang-target translation. Maps rustc → clang triples for iOS targets and passes--target+-isysrootto bindgen.Desktop targets unaffected (iOS branch gated on
target_os == "ios").Validation
cargo check --target aarch64-apple-ios -p joltc-syson macOS host (Xcode 16.4, iPhoneOS 18.5 SDK): succeeds.cargo check --target aarch64-apple-ios-sim -p joltc-sys: succeeds.titan-jolt-3dbuilds against both iOS targets in CI onmacos-latest— see Solidor777/Titan run 25579111428.Stacking
Stacked on #12 (
android-cross-compile-and-target-os-fix) to share the host-vs-target awareness scaffolding. Either PR can merge first — the iOS branch is a strict additive layer. If #12 merges first, this PR auto-narrows.Test plan
cargo check --target aarch64-apple-ios -p joltc-syson macOS hostcargo check --target aarch64-apple-ios-sim -p joltc-syson macOS hostcargo check -p joltc-sys(default host target) — unaffected