Add support for depending on shared libraries on linux.

.bazelci/presubmit.yml

@@ -15,9 +15,12 @@ platforms:
     - "..."
     - "@examples//..."
   macos:
-    build_targets:
-    - "..."
-    - "@examples//..."
-    test_targets:
+    targets: &targets
+    - "--" # Hack for https://github.com/bazelbuild/continuous-integration/pull/245
     - "..."
+    # Skip tests for dylib support on osx, since it's not yet supported.
     - "@examples//..."
+    - "-@examples//ffi/rust_calling_c:matrix_dylib_test"
+    - "-@examples//ffi/rust_calling_c:matrix_dynamically_linked"
+    build_targets: *targets
+    test_targets: *targets

examples/ffi/rust_calling_c/BUILD

@@ -0,0 +1,41 @@
+package(default_visibility = ["//ffi/rust_calling_c:__subpackages__"])
+
+load("@//rust:rust.bzl", "rust_library", "rust_test", "rust_binary")
+
+rust_library(
+    name = "matrix",
+    srcs = [
+        "src/ffi.rs",
+        "src/lib.rs",
+        "src/matrix.rs",
+    ],
+    deps = [
+        "//ffi/rust_calling_c/c:native_matrix",
+        "@libc//:libc",
+    ],
+)
+
+rust_test(
+    name = "matrix_test",
+    deps = [":matrix"],
+)
+
+## Do the same as above, but with a dynamic c library.
+
+rust_library(
+    name = "matrix_dynamically_linked",
+    srcs = [
+        "src/ffi.rs",
+        "src/lib.rs",
+        "src/matrix.rs",
+    ],
+    deps = [
+        "//ffi/rust_calling_c/c:native_matrix_so",
+        "@libc//:libc",
+    ],
+)
+
+rust_test(
+    name = "matrix_dylib_test",
+    deps = [":matrix_dynamically_linked"],
+)

examples/ffi/rust_calling_c/c/BUILD

@@ -0,0 +1,35 @@
+package(default_visibility = ["//ffi/rust_calling_c:__subpackages__"])
+
+cc_library(
+    name = "native_matrix",
+    srcs = ["matrix.c"],
+    hdrs = ["matrix.h"],
+    copts = ["-std=c99"],
+)
+
+cc_test(
+    name = "native_matrix_test",
+    srcs = ["matrix_test.c"],
+    copts = ["-std=c99"],
+    deps = [
+        ":native_matrix",
+    ],
+)
+
+## Do the same as above, but with a dynamic c library.
+
+cc_library(
+    name = "native_matrix_so",
+    srcs = [":libnative_matrix_so.so"],
+    hdrs = ["matrix.h"],
+)
+
+cc_binary(
+    name = "libnative_matrix_so.so",
+    srcs = [
+        "matrix.c",
+        "matrix.h",
+    ],
+    copts = ["-std=c99"],
+    linkshared = True,
+)

examples/matrix/src/matrix.c → examples/ffi/rust_calling_c/c/matrix.c

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include "matrix/src/matrix.h"
+#include "ffi/rust_calling_c/c/matrix.h"
 
 #include <string.h>
 #include <stdio.h>

examples/matrix/src/matrix_test.c → examples/ffi/rust_calling_c/c/matrix_test.c

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include "matrix/src/matrix.h"
+#include "ffi/rust_calling_c/c/matrix.h"
 
 #include <assert.h>
 #include <stdint.h>

examples/matrix/src/ffi.rs → examples/ffi/rust_calling_c/src/ffi.rs

@@ -24,7 +24,7 @@ pub struct Matrix {
     pub data: *mut uint64_t,
 }
 
-#[link(name = "native_matrix")]
+// #[link(name = "native_matrix")] // Don't need this, BUILD file manages linking already.
 extern {
     pub fn matrix_new(rows: size_t, cols: size_t, data: *const uint64_t) -> *mut Matrix;
     pub fn matrix_at(matrix: *const Matrix, row: size_t, col: size_t, n: *mut uint64_t) -> c_int;

examples/matrix/src/lib.rs → examples/ffi/rust_calling_c/src/lib.rs

@@ -16,4 +16,4 @@ extern crate libc;
 
 mod ffi;
 
-pub mod matrix;
+pub mod matrix;

examples/matrix/src/matrix.rs → examples/ffi/rust_calling_c/src/matrix.rs

@@ -18,7 +18,7 @@ use std::ptr;
 
 /// Wrapper around pointer to FFI Matrix struct.
 pub struct Matrix {
-    pub matrix: *mut ffi::Matrix,
+    matrix: *mut ffi::Matrix,
 }
 
 /// Wrapper around low-level FFI Matrix API.
@@ -38,7 +38,7 @@ impl Matrix {
         let mut data_copy: Vec<u64> = vec![0; data.len()];
         data_copy.clone_from_slice(data);
         unsafe {
-            let mut matrix: *mut ffi::Matrix = ffi::matrix_new(rows, cols, data_copy.as_ptr());
+            let matrix: *mut ffi::Matrix = ffi::matrix_new(rows, cols, data_copy.as_ptr());
             if matrix.is_null() {
                 panic!("Failed to allocate Matrix.");
             }