sys: define 'enif_compare_pids' to behave like macro in C code

rustler/src/types/local_pid.rs

@@ -1,7 +1,7 @@
 use crate::wrapper::{pid, ErlNifPid};
 use crate::{Decoder, Encoder, Env, Error, NifResult, Term};
-use std::mem::MaybeUninit;
 use std::cmp::Ordering;
+use std::mem::MaybeUninit;
 
 #[derive(Copy, Clone)]
 pub struct LocalPid {
@@ -37,27 +37,23 @@ impl Encoder for LocalPid {
     }
 }
 
-#[cfg(feature="nif_version_2_15")]
 impl PartialEq for LocalPid {
     fn eq(&self, other: &Self) -> bool {
-        unsafe{ rustler_sys::enif_compare_pids(self.as_c_arg(), other.as_c_arg()) == 0 }
+        unsafe { rustler_sys::enif_compare_pids(self.as_c_arg(), other.as_c_arg()) == 0 }
     }
 }
 
-#[cfg(feature="nif_version_2_15")]
 impl Eq for LocalPid {}
 
-#[cfg(feature="nif_version_2_15")]
 impl PartialOrd for LocalPid {
     fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
         Some(self.cmp(other))
     }
 }
 
-#[cfg(feature="nif_version_2_15")]
 impl Ord for LocalPid {
     fn cmp(&self, other: &Self) -> Ordering {
-        let cmp = unsafe{ rustler_sys::enif_compare_pids(self.as_c_arg(), other.as_c_arg()) };
+        let cmp = unsafe { rustler_sys::enif_compare_pids(self.as_c_arg(), other.as_c_arg()) };
         cmp.cmp(&0)
     }
 }

rustler_sys/build.rs

@@ -858,11 +858,6 @@ fn build_api(b: &mut dyn ApiBuilder, opts: &GenerateOptions) {
             "enif_make_monitor_term",
             "env: *mut ErlNifEnv, mon: *const ErlNifMonitor",
         );
-        b.func(
-            "c_int",
-            "enif_compare_pids",
-            "pid1: *const ErlNifPid, pid2: *const ErlNifPid"
-        );
     }
 
     // 2.16 was introduced in OTP 24

rustler_sys/src/rustler_sys_api.rs

@@ -203,6 +203,12 @@ pub unsafe fn enif_make_pid(_env: *mut ErlNifEnv, pid: ErlNifPid) -> ERL_NIF_TER
     pid.pid
 }
 
+/// See [enif_compare_pids](http://erlang.org/doc/man/erl_nif.html#enif_compare_pids) in the Erlang docs
+pub unsafe fn enif_compare_pids(pid1: *const ErlNifPid, pid2: *const ErlNifPid) -> c_int {
+    // Mimics the implementation of the enif_compare_pids macro
+    enif_compare((*pid1).pid, (*pid2).pid)
+}
+
 /// See [ErlNifSysInfo](http://www.erlang.org/doc/man/erl_nif.html#ErlNifSysInfo) in the Erlang docs.
 #[allow(missing_copy_implementations)]
 #[repr(C)]

rustler_tests/native/rustler_test/src/test_local_pid.rs

@@ -14,4 +14,4 @@ pub fn compare_local_pids(lhs: LocalPid, rhs: LocalPid) -> i32 {
 #[rustler::nif]
 pub fn are_equal_local_pids(lhs: LocalPid, rhs: LocalPid) -> bool {
     lhs == rhs
-}
+}