Cross-Compiling to Linux from macOS

Rafael_Costa · September 21, 2016, 5:14pm

Hello fellow Swift users,

I’m encountering some problems and I wish to know if anyone here has ever come across something similar.

In essence, I want to cross-compile a Swift Project on macOS to run it on Linux. I’m using the following command to (try) to do so:

swift build -c release --build-path ./.build/linux -Xswiftc -static-stdlib -Xswiftc -target -Xswiftc x86_64-unknown-linux-gnu

The “target” parameter is passing to the “swiftc” program just fine. The problem is that it is overwritten by a “target” parameter added automatically by swift-build (that sets the target as the same arch/OS as the host machine)

How can I prevent that? Is it possible to cross-compile for Linux on macOS?

Thanks in advance,
Rafael Costa
rafael@rafaelcosta.me

Karl · September 21, 2016, 9:38pm

It is possible, but I don’t know if swift-build supports it. We don’t really have much comprehensive support for cross-compiling right now.

To cross-compile, you need to set the target, sysroot and tools-directory (the latter only required if compiling an executable, not for swiftmodules). You might also need to set the resource-dir to the lib/swift folder where the target’s standard library is.

···

On 21 Sep 2016, at 19:14, Rafael Costa via swift-users <swift-users@swift.org> wrote:

Hello fellow Swift users,

I’m encountering some problems and I wish to know if anyone here has ever come across something similar.

In essence, I want to cross-compile a Swift Project on macOS to run it on Linux. I’m using the following command to (try) to do so:

swift build -c release --build-path ./.build/linux -Xswiftc -static-stdlib -Xswiftc -target -Xswiftc x86_64-unknown-linux-gnu

The “target” parameter is passing to the “swiftc” program just fine. The problem is that it is overwritten by a “target” parameter added automatically by swift-build (that sets the target as the same arch/OS as the host machine)

How can I prevent that? Is it possible to cross-compile for Linux on macOS?

Thanks in advance,
Rafael Costa
rafael@rafaelcosta.me <mailto:rafael@rafaelcosta.me>

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swift-users mailing list
swift-users@swift.org
https://lists.swift.org/mailman/listinfo/swift-users

Karl · September 21, 2016, 9:45pm

For example, this is what we do in LLDB to cross-compile the REPL:

github.com

apple/swift-lldb/blob/587e781a6fab4db0338a6e71bbc7fc3475f9d43c/tools/repl/swift/CMakeLists.txt#L11


      
          set(LLVM_NO_RTTI 1)
          
          include(AddLLVM)
          include(SwiftAddCustomCommandTarget)
          
          set(output_dir "${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/bin")
          set(module_cache_dir "${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/repl_swift_module_cache")
          
          set(swift_compile_cmd "${LLDB_SWIFTC}" -resource-dir "${LLDB_PATH_TO_SWIFT_BUILD}/lib/swift" -module-cache-path "${module_cache_dir}")
          if(CMAKE_CROSSCOMPILING)
            set(swift_compile_cmd ${swift_compile_cmd} -target "${LLVM_HOST_TRIPLE}" -sdk "${CMAKE_SYSROOT}")
            if(CMAKE_C_COMPILER_EXTERNAL_TOOLCHAIN)
          	  set(swift_compile_cmd ${swift_compile_cmd} -tools-directory "${CMAKE_C_COMPILER_EXTERNAL_TOOLCHAIN}")
            endif()
          endif()
          
          if (CMAKE_SYSTEM_NAME MATCHES "Linux")  
            add_custom_command_target(
                repl_swift_target
                COMMAND ${swift_compile_cmd} -o "${output_dir}/repl_swift" -Xlinker -rpath -Xlinker \$ORIGIN/../lib/swift/linux "${CMAKE_CURRENT_SOURCE_DIR}/main.swift"
                OUTPUT "${output_dir}/repl_swift"

···

On 21 Sep 2016, at 19:14, Rafael Costa via swift-users <swift-users@swift.org> wrote:

Hello fellow Swift users,

I’m encountering some problems and I wish to know if anyone here has ever come across something similar.

In essence, I want to cross-compile a Swift Project on macOS to run it on Linux. I’m using the following command to (try) to do so:

swift build -c release --build-path ./.build/linux -Xswiftc -static-stdlib -Xswiftc -target -Xswiftc x86_64-unknown-linux-gnu

The “target” parameter is passing to the “swiftc” program just fine. The problem is that it is overwritten by a “target” parameter added automatically by swift-build (that sets the target as the same arch/OS as the host machine)

How can I prevent that? Is it possible to cross-compile for Linux on macOS?

Thanks in advance,
Rafael Costa
rafael@rafaelcosta.me <mailto:rafael@rafaelcosta.me>

_______________________________________________
swift-users mailing list
swift-users@swift.org
https://lists.swift.org/mailman/listinfo/swift-users

Rafael_Costa · September 21, 2016, 10:04pm

Thank you Karl

···

Enviado do meu iPhone

Em 21 de set de 2016, às 18:45, Karl <razielim@gmail.com> escreveu:

On 21 Sep 2016, at 19:14, Rafael Costa via swift-users <swift-users@swift.org> wrote:

Hello fellow Swift users,

I’m encountering some problems and I wish to know if anyone here has ever come across something similar.

In essence, I want to cross-compile a Swift Project on macOS to run it on Linux. I’m using the following command to (try) to do so:

swift build -c release --build-path ./.build/linux -Xswiftc -static-stdlib -Xswiftc -target -Xswiftc x86_64-unknown-linux-gnu

The “target” parameter is passing to the “swiftc” program just fine. The problem is that it is overwritten by a “target” parameter added automatically by swift-build (that sets the target as the same arch/OS as the host machine)

How can I prevent that? Is it possible to cross-compile for Linux on macOS?

Thanks in advance,
Rafael Costa
rafael@rafaelcosta.me

_______________________________________________
swift-users mailing list
swift-users@swift.org
https://lists.swift.org/mailman/listinfo/swift-users

For example, this is what we do in LLDB to cross-compile the REPL:

https://github.com/apple/swift-lldb/blob/587e781a6fab4db0338a6e71bbc7fc3475f9d43c/tools/repl/swift/CMakeLists.txt#L11