cmake_including_rust: A CMake repository from AndrewGaspar

Compiling a C++ Program with a Statically-Linked Rust Library Using CMake

Project Set-Up

This is an test case for adding Rust to a C++ project that is currently being compiled using CMake, through the ExternalProject module. It's desired to have this library be statically linked (using a *.a file) vs. dynamically-linked (using a .so file).

The project can built by doing the following:

$ cmake .
$ make

The set-up is currently the following:

    ├── CMakeLists.txt
    ├── README.md
    ├── rust_hello
    │   ├── binding
    │   │   └── rust_hello.h
    │   ├── Cargo.toml
    │   └── src
    │       └── lib.rs
    └── src
        └── main.cpp

The Rust library (lib.rs) is compiled using cargo build through the ExternalProject module in CMake, and has it's binding automatically generated using the cbindgen tool, with the resulting artifacts set in the target folder that gets created under rust_hello.

The Cargo.toml file for that project specifies that both a static and dynamic library should be built, by specifying crate-type = ["staticlib","cdylib"] under [lib]. I have verified that both of these are created.

However, I begin running into an issue when I want to use the println!() macro. The Rust library currently has two functions:

hello_from_rust() -> uses println!() to output "hello, world! -- from a Rust function!" to the command line
return_a_four() returns an i32 type with a value of 4

Current Issues

Everything works fine, as long as I am compiling with the dynamic .so library instead of the .a library. This gets specified near the end of the CMakeLists.txt file, (there's a TO_DO located above that section, which should be found fairly easily). When I compile using the dynamic library, everything works as expected such that I end up with a binary called say_hello in the main directory, that when run , and I get the following output:

username@user:~/rust-projects/cmake_including_rust$ ./say_hello
hello, world! -- from c++ main()
hello, world! -- from a Rust function!
my_int now equals: 4
                   ^ should be a '4'

However, if I start from the same clean version of the repository (clear all of the new cmake and cargo artifacts), and just alter the lines the CMakeLists.txt files s.t. they read

target_link_libraries(
  say_hello
  debug "${PROJECT_SOURCE_DIR}/rust_hello/target/debug/librust_hello.a"
  optimized "${PROJECT_SOURCE_DIR}/rust_hello/target/release/librust_hello.a"
)

and repeat the same build steps, I end up with the following during the make step:

username@user:~/rust-projects/cmake_including_rust$ make
Scanning dependencies of target rust_hello
[ 10%] Creating directories for 'rust_hello'
[ 20%] No download step for 'rust_hello'
[ 30%] No patch step for 'rust_hello'
[ 40%] No update step for 'rust_hello'
[ 50%] No configure step for 'rust_hello'
[ 60%] Performing build step for 'rust_hello'
-- rust_hello build command succeeded.  See also /home/username/rust-projects/cmake_including_rust/RUST/src/rust_hello-stamp/rust_hello-build-*.log
[ 70%] No install step for 'rust_hello'
[ 80%] Completed 'rust_hello'
[ 80%] Built target rust_hello
Scanning dependencies of target say_hello
[ 90%] Building CXX object CMakeFiles/say_hello.dir/src/main.cpp.o
[100%] Linking CXX executable say_hello
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::backtrace::printing::dladdr::resolve_symname':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/backtrace/printing/dladdr.rs:15: undefined reference to `dladdr'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::mutex::Mutex::init':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/mutex.rs:45: undefined reference to `pthread_mutexattr_init'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/mutex.rs:47: undefined reference to `pthread_mutexattr_settype'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/mutex.rs:51: undefined reference to `pthread_mutexattr_destroy'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/mutex.rs:45: undefined reference to `pthread_mutexattr_init'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/mutex.rs:47: undefined reference to `pthread_mutexattr_settype'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/mutex.rs:51: undefined reference to `pthread_mutexattr_destroy'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::mutex::ReentrantMutex::init':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/mutex.rs:99: undefined reference to `pthread_mutexattr_init'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/mutex.rs:101: undefined reference to `pthread_mutexattr_settype'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/mutex.rs:106: undefined reference to `pthread_mutexattr_destroy'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/mutex.rs:99: undefined reference to `pthread_mutexattr_init'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/mutex.rs:101: undefined reference to `pthread_mutexattr_settype'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/mutex.rs:106: undefined reference to `pthread_mutexattr_destroy'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::mutex::Mutex::init':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/mutex.rs:45: undefined reference to `pthread_mutexattr_init'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/mutex.rs:47: undefined reference to `pthread_mutexattr_settype'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/mutex.rs:51: undefined reference to `pthread_mutexattr_destroy'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::backtrace::printing::dladdr::resolve_symname':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/backtrace/printing/dladdr.rs:15: undefined reference to `dladdr'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::thread_local::create':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread_local.rs:11: undefined reference to `pthread_key_create'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread_local.rs:11: undefined reference to `pthread_key_create'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::thread_local::destroy':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread_local.rs:28: undefined reference to `pthread_key_delete'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread_local.rs:28: undefined reference to `pthread_key_delete'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::thread_local::create':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread_local.rs:11: undefined reference to `pthread_key_create'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread_local.rs:11: undefined reference to `pthread_key_create'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::thread_local::destroy':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread_local.rs:28: undefined reference to `pthread_key_delete'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread_local.rs:28: undefined reference to `pthread_key_delete'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::thread_local::get':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread_local.rs:23: undefined reference to `pthread_getspecific'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::thread_local::create':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread_local.rs:11: undefined reference to `pthread_key_create'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread_local.rs:11: undefined reference to `pthread_key_create'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::thread_local::destroy':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread_local.rs:28: undefined reference to `pthread_key_delete'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread_local.rs:28: undefined reference to `pthread_key_delete'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::thread_local::set':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread_local.rs:17: undefined reference to `pthread_setspecific'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::thread_local::create':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread_local.rs:11: undefined reference to `pthread_key_create'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread_local.rs:11: undefined reference to `pthread_key_create'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::thread_local::destroy':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread_local.rs:28: undefined reference to `pthread_key_delete'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread_local.rs:28: undefined reference to `pthread_key_delete'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::thread_local::get':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread_local.rs:23: undefined reference to `pthread_getspecific'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread_local.rs:23: undefined reference to `pthread_getspecific'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::thread_local::create':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread_local.rs:11: undefined reference to `pthread_key_create'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread_local.rs:11: undefined reference to `pthread_key_create'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::thread_local::destroy':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread_local.rs:28: undefined reference to `pthread_key_delete'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread_local.rs:28: undefined reference to `pthread_key_delete'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::thread_local::set':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread_local.rs:17: undefined reference to `pthread_setspecific'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::rwlock::RWLock::write':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/rwlock.rs:72: undefined reference to `pthread_rwlock_wrlock'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::rwlock::RWLock::raw_unlock':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/rwlock.rs:103: undefined reference to `pthread_rwlock_unlock'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/rwlock.rs:103: undefined reference to `pthread_rwlock_unlock'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::rwlock::RWLock::write':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/rwlock.rs:72: undefined reference to `pthread_rwlock_wrlock'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::rwlock::RWLock::raw_unlock':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/rwlock.rs:103: undefined reference to `pthread_rwlock_unlock'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/rwlock.rs:103: undefined reference to `pthread_rwlock_unlock'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::rwlock::RWLock::read':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/rwlock.rs:24: undefined reference to `pthread_rwlock_rdlock'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::rwlock::RWLock::raw_unlock':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/rwlock.rs:103: undefined reference to `pthread_rwlock_unlock'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/rwlock.rs:103: undefined reference to `pthread_rwlock_unlock'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::thread::guard::get_stack_start':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread.rs:267: undefined reference to `pthread_getattr_np'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread.rs:271: undefined reference to `pthread_attr_getstack'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::weak::fetch':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/weak.rs:68: undefined reference to `dlsym'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::condvar::Condvar::init':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/condvar.rs:48: undefined reference to `pthread_condattr_setclock'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::process::process_inner::<impl std::sys::unix::process::process_common::Command>::do_exec':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/process/process_unix.rs:229: undefined reference to `pthread_sigmask'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::thread::pthread_attr_setstacksize':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread.rs:32: undefined reference to `pthread_attr_setstacksize'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::thread::Thread::new':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread.rs:64: undefined reference to `pthread_attr_setstacksize'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread.rs:69: undefined reference to `pthread_create'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::thread::Thread::join':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread.rs:168: undefined reference to `pthread_join'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `<std::sys::unix::thread::Thread as core::ops::drop::Drop>::drop':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread.rs:186: undefined reference to `pthread_detach'
rust_hello/target/release/librust_hello.a(std-e39317eb74365d3c.std.6yaz5a4r-cgu.0.rcgu.o): In function `std::sys::unix::thread::guard::current':
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread.rs:365: undefined reference to `pthread_getattr_np'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread.rs:368: undefined reference to `pthread_attr_getguardsize'
/rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858//src/libstd/sys/unix/thread.rs:374: undefined reference to `pthread_attr_getstack'
collect2: error: ld returned 1 exit status
CMakeFiles/say_hello.dir/build.make:95: recipe for target 'say_hello' failed
make[2]: *** [say_hello] Error 1
CMakeFiles/Makefile2:67: recipe for target 'CMakeFiles/say_hello.dir/all' failed
make[1]: *** [CMakeFiles/say_hello.dir/all] Error 2
Makefile:83: recipe for target 'all' failed
make: *** [all] Error 2

What's more, if I comment out the hello_from_rust() function and comment it out in main.cpp, the return_a_four() function works fine! This makes me think it has something to the println!() function itself, and how that interacts with the environment itself. I don't even need to call the function or anything-- it's the build step which has the problem, so I don't think it's a runtime issue or anything along those lines.

I've done a bit of digging, but I can't seem to figure out why this is happening. It seems like there's a missing dependency in either pthread or with dladdr, although as far as I can tell, they're installed in my system and called out in the CMakeLists.txt file. I think something similar has been brought up in a Reddit thread (see below), although I believe the user was working on Windows (I'm on Linux), and I haven't been able to figure out the right combination of things to fix this problem (even though I'm mirroring his code pretty closely; thanks Eoin!)

Any help would be really appreciated!

Here are my current system specs:

Ubuntu 18.04LTS
Intel i5 processor
cmake version 3.10.2
GNU make 4.1
g++/gcc version 7.3.0
cargo and rustc version 1.33.0 (stable)

Reddit thread about this:

Rust Embedded's "A little Rust with your C":

https://rust-embedded.github.io/book/interoperability/rust-with-c.html

A project using CMake and Rust to run Rust on a BBC micro:bit (search for ExternalProject):

https://github.com/rossng/microbit-rust-hal

AndrewGaspar/cmake_including_rust

Compiling a C++ Program with a Statically-Linked Rust Library Using CMake

Project Set-Up

Current Issues