test: Add an example build script usage crate

Add a example / test crate named `example-build-script`
to the project workspace.

Pull in and link a simple Rust binary to several Conan dependencies:

- openssl
- libxml2
- zlib

Test that the example Rust binary links and runs correctly.

.github/workflows/rust.yml

@@ -26,6 +26,10 @@ jobs:
       run: conan profile detect
     - name: Run tests
       run: cargo test --verbose
+    - name: Test build the example crates
+      run: cargo build --all
+    - name: Test run the build script example
+      run: cargo run -p example-build-script
   fmt:
     name: Check code formatting
     runs-on: ubuntu-latest

.gitlab-ci.yml

@@ -41,3 +41,5 @@ runtests:
     stage: test
     script:
       - cargo test --verbose
+      - cargo build --all
+      - cargo run -p example-build-script

Cargo.toml

@@ -12,3 +12,6 @@ readme = "README.md"
 
 [dependencies]
 serde_json = "1.0"
+
+[workspace]
+members = [ "example-build-script" ]

README.md

@@ -43,6 +43,9 @@ fn main() {
 The Conan executable is assumed to be named `conan` unless
 the `CONAN` environment variable is set to override.
 
+An example Rust crate using `conan2-rs` to link Conan dependencies
+can also be found in the project repository.
+
 ## Advanced usage
 
 Using custom Conan profiles with names derived from the Cargo target information:

example-build-script/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "example-build-script"
+description = "A working example of using Conan dependencies with conan2-rs"
+version = "0.1.0"
+edition = "2021"
+
+[build-dependencies]
+conan2 = { path = "../" }

example-build-script/build.rs

@@ -0,0 +1,5 @@
+use conan2::ConanInstall;
+
+fn main() {
+    ConanInstall::new().build("missing").run().parse().emit();
+}

example-build-script/conanfile.txt

@@ -0,0 +1,4 @@
+[requires]
+zlib/1.3
+libxml2/2.11.4
+openssl/3.1.3

example-build-script/src/main.rs

@@ -0,0 +1,43 @@
+use std::ffi::{c_int, c_uint, c_ulong, c_void};
+
+extern "C" {
+    /// zlib
+    fn adler32(adler: c_ulong, buf: *const c_void, len: c_uint) -> c_ulong;
+
+    /// libxml2
+    fn xmlCheckVersion(version: c_int);
+
+    /// libiconv
+    fn iconv_open(tocode: *const u8, fromcode: *const u8) -> *const c_void;
+
+    /// libcharset
+    fn locale_charset() -> *const u8;
+
+    /// libcrypto
+    fn EVP_MD_CTX_new() -> *const c_void;
+
+    /// libssl
+    fn OPENSSL_init_ssl(opts: u64, buf: *const c_void) -> c_int;
+}
+
+fn main() {
+    unsafe {
+        // zlib
+        adler32(0, std::ptr::null(), 0);
+
+        // libxml2
+        xmlCheckVersion(2_00_00);
+
+        // libiconv
+        iconv_open(b"a".as_ptr(), b"b".as_ptr());
+
+        // libcharset
+        locale_charset();
+
+        // libcrypto
+        EVP_MD_CTX_new();
+
+        // libssl
+        OPENSSL_init_ssl(0, std::ptr::null());
+    };
+}