search

rust-lang / cmake-rs

Rust build dependency for running cmake
https://docs.rs/cmake
Apache License 2.0
301 stars 121 forks source link

Improve cross compiling support #158

Closed messense closed 1 year ago

messense commented 2 years ago

This PR changes cmake-rs to fill out CMAKE_SYSTEM_NAME and CMAKE_SYSTEM_PROCESSOR based CARGO_CFG_TARGET_OS and CARGO_CFG_TARGET_ARCH when cross compiling while CMAKE_TOOLCHAIN_FILE and CMAKE_SYSTEM_NAME isn't set by user.

It's tested on CI using cross.

Closes #75 Closes #80 Closes #151

jrose-signal commented 1 year ago

I'm afraid this broke no-toolchain cross-compilation using Visual Studio, from an x86_64 Windows host to aarch64-pc-windows-msvc. Things are a bit clunky there in general (the existing support goes through platforms and does not set CMAKE_SYSTEM_PROCESSOR), but it was working in 1.48.0 (and I'm afraid we hadn't been testing with new crate versions, so we didn't discover this sooner).

(Specifically, the auto-search for CMAKE_C_COMPILER and CMAKE_CXX_COMPILER doesn't kick in, even though it works fine for a non-cross-compile MSVS generator build.)

jrose-signal commented 1 year ago

Workaround: set CMAKE_SYSTEM_NAME to an empty string, which counts as defined for this crate, but unset for CMake itself.

jrose-signal commented 1 year ago

Turns out this also broke cross-compiling to Mac Catalyst targets (*-apple-ios-macabi), because CMake doesn't like having CMAKE_SYSTEM_NAME set to "iOS" while compiling against a macOS sysroot. That should probably eventually be fixed in CMake itself, but for now setting CMAKE_SYSTEM_NAME back to "Darwin" does work, at least for simple libraries. I don't know if you want to put that in this crate, though.

EDIT (months later): here's CMake not deciding what to do about Catalyst, which isn't cmake-rs's fault.