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+# rust-on-ios
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+This is a quick proof-of-concept for a bitcode-enabled library built from Rust intended for consumption in an iOS app built in Unity (2018.4.11f1)
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+Unity defaults to embedding bitcode meaning all static dependencies must do likewise. Rust, by default, does not embed bitcode for static library targets. We can use `-C lto -Z embed-bitcode` to ask Rust to embed bitcode (afaict `-C lto` is required because the shipped iOS rust-std libs also need to embed bitcode.)
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+
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+Naturally both Rust and Apple have forked LLVM and they are not always in-sync which is the current major problem [outlined here](https://github.com/rust-lang/rust/issues/35968). For Xcode 11.1 the latest Rust version we can use is `nightly-2019-07-17`.
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+## Building
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+- cd librusty
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+- cargo install cargo-lipo
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+- rustup target add aarch64-apple-ios
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+- cargo lipo --targets aarch64-apple-ios --release
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+- cp target/universal/release/librusty.a ../unity/Assets/Plugins/iOS/librusty.a
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+## So, what?
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+Until Rust officially decides to support bitcode we have to jump through hoops in order to do so:
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+- We must use a specific (nightly) compiler version
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+- Xcode betas/updates **may** break linkability of our static library
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+- Downstream developers **may not** all be on the same (latest) version of Xcode
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