Use cmake_package to link against LLVM

Currently, we are using the same approach as the llvm-sys package to
facilitate linking against LLVM, replicating a lot of their 'build.rs'
in the process. The process uses the `llvm-config` binary to find the
necessary libraries and include directories to link against LLVM.

This method has some downsides, mainly not being able to find the binary
if it is not in the PATH and `llvm-config` not properly reporting that
FFI needs to be linked. We noticed that these problems do not occur for
the CMake build of the C++ Nyxstone library. This commit introduces the
`cmake_package` crate to use CMake's `find_library` function to find the
LLVM libraries.

.github/workflows/rust.yml

@@ -15,7 +15,6 @@ jobs:
     env:
       working-dir: ./bindings/rust
       NYXSTONE_LLVM_PREFIX: "/usr/lib/llvm-15/"
-      NYXSTONE_LINK_FFI: "1"
     steps:
     - uses: actions/checkout@v4
     - name: Packages
@@ -43,10 +42,10 @@ jobs:
     - name: Packages
       run: brew install llvm@15
     - name: Build
-      run: RUSTFLAGS="-L$(brew --prefix zstd)/lib" NYXSTONE_LLVM_PREFIX="$(brew --prefix llvm@15)" NYXSTONE_LINK_FFI=1 cargo build
+      run: RUSTFLAGS="-L$(brew --prefix zstd)/lib" NYXSTONE_LLVM_PREFIX="$(brew --prefix llvm@15)" cargo build
       working-directory: ${{ env.working-dir }}
     - name: Run tests
-      run: RUSTFLAGS="-L$(brew --prefix zstd)/lib" RUSTDOCFLAGS="-L$(brew --prefix zstd)/lib" NYXSTONE_LLVM_PREFIX="$(brew --prefix llvm@15)" NYXSTONE_LINK_FFI=1 cargo test
+      run: RUSTFLAGS="-L$(brew --prefix zstd)/lib" RUSTDOCFLAGS="-L$(brew --prefix zstd)/lib" NYXSTONE_LLVM_PREFIX="$(brew --prefix llvm@15)" cargo test
       working-directory: ${{ env.working-dir }}
 
   mac-llvm-16:
@@ -58,10 +57,10 @@ jobs:
     - name: Packages
       run: brew install llvm@16
     - name: Build
-      run: RUSTFLAGS="-L$(brew --prefix zstd)/lib" NYXSTONE_LLVM_PREFIX="$(brew --prefix llvm@16)" NYXSTONE_LINK_FFI=1 cargo build
+      run: RUSTFLAGS="-L$(brew --prefix zstd)/lib" NYXSTONE_LLVM_PREFIX="$(brew --prefix llvm@16)" cargo build
       working-directory: ${{ env.working-dir }}
     - name: Run tests
-      run: RUSTFLAGS="-L$(brew --prefix zstd)/lib" RUSTDOCFLAGS="-L$(brew --prefix zstd)/lib" NYXSTONE_LLVM_PREFIX="$(brew --prefix llvm@16)" NYXSTONE_LINK_FFI=1 cargo test
+      run: RUSTFLAGS="-L$(brew --prefix zstd)/lib" RUSTDOCFLAGS="-L$(brew --prefix zstd)/lib" NYXSTONE_LLVM_PREFIX="$(brew --prefix llvm@16)" cargo test
       working-directory: ${{ env.working-dir }}
 
   mac-llvm-17:
@@ -73,10 +72,10 @@ jobs:
     - name: Packages
       run: brew install llvm@17
     - name: Build
-      run: RUSTFLAGS="-L$(brew --prefix zstd)/lib" NYXSTONE_LLVM_PREFIX="$(brew --prefix llvm@17)" NYXSTONE_LINK_FFI=1 cargo build
+      run: RUSTFLAGS="-L$(brew --prefix zstd)/lib" NYXSTONE_LLVM_PREFIX="$(brew --prefix llvm@17)" cargo build
       working-directory: ${{ env.working-dir }}
     - name: Run tests
-      run: RUSTFLAGS="-L$(brew --prefix zstd)/lib" RUSTDOCFLAGS="-L$(brew --prefix zstd)/lib" NYXSTONE_LLVM_PREFIX="$(brew --prefix llvm@17)" NYXSTONE_LINK_FFI=1 cargo test
+      run: RUSTFLAGS="-L$(brew --prefix zstd)/lib" RUSTDOCFLAGS="-L$(brew --prefix zstd)/lib" NYXSTONE_LLVM_PREFIX="$(brew --prefix llvm@17)" cargo test
       working-directory: ${{ env.working-dir }}
 
   mac-llvm-18:
@@ -88,9 +87,9 @@ jobs:
     - name: Packages
       run: brew install llvm@18
     - name: Build
-      run: RUSTFLAGS="-L$(brew --prefix zstd)/lib" NYXSTONE_LLVM_PREFIX="$(brew --prefix llvm@18)" NYXSTONE_LINK_FFI=1 cargo build
+      run: RUSTFLAGS="-L$(brew --prefix zstd)/lib" NYXSTONE_LLVM_PREFIX="$(brew --prefix llvm@18)" cargo build
       working-directory: ${{ env.working-dir }}
     - name: Run tests
-      run: RUSTFLAGS="-L$(brew --prefix zstd)/lib" RUSTDOCFLAGS="-L$(brew --prefix zstd)/lib" NYXSTONE_LLVM_PREFIX="$(brew --prefix llvm@18)" NYXSTONE_LINK_FFI=1 cargo test
+      run: RUSTFLAGS="-L$(brew --prefix zstd)/lib" RUSTDOCFLAGS="-L$(brew --prefix zstd)/lib" NYXSTONE_LLVM_PREFIX="$(brew --prefix llvm@18)" cargo test
       working-directory: ${{ env.working-dir }}
 

bindings/rust/Cargo.toml

@@ -24,6 +24,7 @@ clap = { version = "4.5", features = ["derive"] }
 [build-dependencies]
 cxx-build = "1.0.94"
 anyhow = { version = "1.0.68", default-features = true }
+cmake-package = "0.1.2"
 
 [lib]
 path = "src/lib.rs"

bindings/rust/README.md

@@ -7,11 +7,10 @@ Official bindings for the Nyxstone assembler/disassembler engine.
 
 ## Building
 
-The project can be build via `cargo build`, as long as LLVM with a major version in the range 15-18 is installed in the `$PATH` or the environment variable `$NYXSTONE_LLVM_PREFIX` points to the installation location of a LLVM library.
-
-LLVM might be linked against FFI, but not correctly report this fact via `llvm-config`. If your LLVM does link FFI and
-Nyxstone fails to run, set the `NYXSTONE_LINK_FFI` environment variable to `1`, which will ensure that Nyxstone
-links against `libffi`.
+The project can be build via `cargo build`, as long as LLVM with a major version in the range 15 to 18 is availabe to CMake
+and cmake is installed on the system. If your installation of LLVM is installed in a non-standard location, you can set
+`NYXSTONE_LLVM_PREFIX` to tell Nyxstone or use the `CMAKE_INCLUDE_PATH` environment variable to add the directory to the
+CMake search path.  
 
 ## Installation