cmake: add example how to integrate cargo

5 files changed, 94 insertions, 0 deletions

diff --git a/content/2022-05-30-cmake-cargo-example/libcalc/.gitignore b/content/2022-05-30-cmake-cargo-example/libcalc/.gitignore
new file mode 100644
index 0000000..008b9b4
--- /dev/null
+++ b/content/2022-05-30-cmake-cargo-example/libcalc/.gitignore
@@ -0,0 +1,3 @@
+/target
+Cargo.lock
+libcalc.h
diff --git a/content/2022-05-30-cmake-cargo-example/libcalc/CMakeLists.txt b/content/2022-05-30-cmake-cargo-example/libcalc/CMakeLists.txt
new file mode 100644
index 0000000..2abab17
--- /dev/null
+++ b/content/2022-05-30-cmake-cargo-example/libcalc/CMakeLists.txt
@@ -0,0 +1,48 @@
+cmake_minimum_required(VERSION 3.14)
+
+set(BDIR ${CMAKE_BINARY_DIR}/libcalc)
+
+# Define external project to build rust lib with cargo.
+include(ExternalProject)
+ExternalProject_Add(
+    ext_libcalc
+    # Always trigger build, let cargo decide if we want to rebuild.
+    BUILD_ALWAYS         ON
+    CONFIGURE_COMMAND    ""
+    # Can not pass arguments to build.rs and was not able to set env variables
+    # for the external build command, therefore use 'env' to setup env var.
+    BUILD_COMMAND        env LIBCALC_BUILD_DIR=${BDIR}
+                         cargo build --target-dir ${BDIR} "$<IF:$<CONFIG:Release>,--release,>"
+    BUILD_BYPRODUCTS     ${BDIR}/$<IF:$<CONFIG:Release>,release,debug>/libcalc.a
+                         ${BDIR}/libcalc.h
+    INSTALL_COMMAND      ""
+    # Location of sources (since we don't download).
+    SOURCE_DIR           "${CMAKE_CURRENT_SOURCE_DIR}"
+    # Build dir location used as CWD for build commands.
+    BINARY_DIR           "${CMAKE_CURRENT_SOURCE_DIR}"
+    # Root directory for external project in cmake build dir.
+    PREFIX               "libcalc"
+    # Log directory (relative to PREFIX).
+    LOG_DIR              "log"
+    # Log build step.
+    LOG_BUILD             ON
+    # In case of error output log on terminal.
+    LOG_OUTPUT_ON_FAILURE ON
+)
+
+# Define pseudo target (import lib) for usage in cmake and let it depend on
+# the cargo build.
+add_library(libcalc STATIC IMPORTED GLOBAL)
+add_dependencies(libcalc ext_libcalc)
+
+# Configure the import locations (libs) for the import lib.
+
+set_target_properties(libcalc PROPERTIES
+    IMPORTED_CONFIGURATIONS "Debug;Release"
+    IMPORTED_LOCATION       "${BDIR}/release/libcalc.a"
+    IMPORTED_LOCATION_DEBUG "${BDIR}/debug/libcalc.a"
+)
+
+# Configure the additional interface for they pseudo target.
+
+target_include_directories(libcalc INTERFACE "${BDIR}")
diff --git a/content/2022-05-30-cmake-cargo-example/libcalc/Cargo.toml b/content/2022-05-30-cmake-cargo-example/libcalc/Cargo.toml
new file mode 100644
index 0000000..23ea182
--- /dev/null
+++ b/content/2022-05-30-cmake-cargo-example/libcalc/Cargo.toml
@@ -0,0 +1,10 @@
+[package]
+name = "calc"
+version = "0.1.0"
+edition = "2021"
+
+[lib]
+crate-type = ["staticlib"]
+
+[build-dependencies]
+cbindgen = "0.*"
diff --git a/content/2022-05-30-cmake-cargo-example/libcalc/build.rs b/content/2022-05-30-cmake-cargo-example/libcalc/build.rs
new file mode 100644
index 0000000..acfa6a7
--- /dev/null
+++ b/content/2022-05-30-cmake-cargo-example/libcalc/build.rs
@@ -0,0 +1,24 @@
+fn main() {
+    let crate_dir = std::env::var("CARGO_MANIFEST_DIR").unwrap();
+
+    let out_file = format!("{}/libcalc.h", std::env::var("LIBCALC_BUILD_DIR").unwrap_or(String::from(".")));
+
+    let cfg = cbindgen::Config {
+        cpp_compat: true,
+        ..Default::default()
+    };
+
+    if std::path::Path::new(&out_file).exists() {
+        std::fs::remove_file(&out_file).unwrap();
+    }
+
+    let ok = cbindgen::Builder::new()
+        .with_config(cfg)
+        .with_crate(crate_dir)
+        .with_language(cbindgen::Language::C)
+        .with_include_guard("LIBCALC_H")
+        .generate()
+        .expect("Unable to generate bindings")
+        .write_to_file(&out_file);
+    assert!(ok);
+}
diff --git a/content/2022-05-30-cmake-cargo-example/libcalc/src/lib.rs b/content/2022-05-30-cmake-cargo-example/libcalc/src/lib.rs
new file mode 100644
index 0000000..a36aace
--- /dev/null
+++ b/content/2022-05-30-cmake-cargo-example/libcalc/src/lib.rs
@@ -0,0 +1,9 @@
+#[no_mangle]
+pub extern "C" fn wrap_add(a: i32, b: i32) -> i32 {
+    a.wrapping_add(b)
+}
+
+#[no_mangle]
+pub extern "C" fn sat_add(a: i32, b: i32) -> i32 {
+    a.saturating_add(b)
+}