Reverted mistaken missed functionality

src/cp_sat_wrapper.cpp

@@ -61,6 +61,20 @@ cp_sat_wrapper_cp_model_stats(unsigned char* model_buf, size_t model_size) {
     return strdup(stats.c_str());
 }
 
+extern "C" char*
+cp_sat_wrapper_cp_solver_response_stats(
+    unsigned char* response_buf,
+    size_t response_size,
+    bool has_objective)
+{
+    sat::CpSolverResponse response;
+    const bool res = response.ParseFromArray(response_buf, response_size);
+    assert(res);
+
+    const std::string stats = sat::CpSolverResponseStats(response, has_objective);
+    return strdup(stats.c_str());
+}
+
 extern "C" char*
 cp_sat_wrapper_validate_cp_model(unsigned char* model_buf, size_t model_size) {
     sat::CpModelProto model;

src/ffi.rs

@@ -17,6 +17,11 @@ extern "C" {
         out_size: &mut usize,
     ) -> *mut u8;
     fn cp_sat_wrapper_cp_model_stats(model_buf: *const u8, model_size: usize) -> *mut c_char;
+    fn cp_sat_wrapper_cp_solver_response_stats(
+        response_buf: *const u8,
+        response_size: usize,
+        has_objective: bool,
+    ) -> *mut c_char;
     fn cp_sat_wrapper_validate_cp_model(model_buf: *const u8, model_size: usize) -> *mut c_char;
     fn cp_sat_wrapper_solution_is_feasible(
         model_buf: *const u8,
@@ -81,6 +86,29 @@ pub fn cp_model_stats(model: &proto::CpModelProto) -> String {
     res
 }
 
+/// Returns a string with some statistics on the solver response.
+///
+/// If the second argument is false, we will just display NA for the
+/// objective value instead of zero. It is not really needed but it
+/// makes things a bit clearer to see that there is no objective.
+pub fn cp_solver_response_stats(response: &proto::CpSolverResponse, has_objective: bool) -> String {
+    let mut response_buf = Vec::default();
+    response.encode(&mut response_buf).unwrap();
+    let char_ptr = unsafe {
+        cp_sat_wrapper_cp_solver_response_stats(
+            response_buf.as_ptr(),
+            response_buf.len(),
+            has_objective,
+        )
+    };
+    let res = unsafe { CStr::from_ptr(char_ptr) }
+        .to_str()
+        .unwrap()
+        .to_owned();
+    unsafe { libc::free(char_ptr as _) };
+    res
+}
+
 /// Verifies that the given model satisfies all the properties
 /// described in the proto comments. Returns an empty string if it is
 /// the case, otherwise fails at the first error and returns a

src/lib.rs

@@ -33,7 +33,7 @@
 //!     let response = model.solve();
 //!     println!(
 //!         "{}",
-//!         cp_sat::ffi::cp_model_stats(&model.proto())
+//!         cp_sat::ffi::cp_solver_response_stats(&response, false)
 //!     );
 //!
 //!     if response.status() == CpSolverStatus::Optimal {