Expand macro gating

Author: Aaron1011

src/macros.rs

@@ -164,6 +164,21 @@ cfg_if! {
                 }
             )*)
         }
+
+        macro_rules! const_fn {
+            ($($({$constness:ident})* fn $i:ident(
+                        $($arg:ident: $argty:ty),*
+            ) -> $ret:ty {
+                $($body:stmt);*
+            })*) => ($(
+                #[inline]
+                $($constness)* fn $i($($arg: $argty),*
+                ) -> $ret {
+                    $($body);*
+                }
+            )*)
+        }
+        
     } else {
         #[allow(unused_macros)]
         macro_rules! f {
@@ -173,7 +188,22 @@ cfg_if! {
                 $($body:stmt);*
             })*) => ($(
                 #[inline]
-                pub unsafe extern fn $i($($arg: $argty),*) -> $ret {
+                pub unsafe extern fn $i($($arg: $argty),*
+                ) -> $ret {
+                    $($body);*
+                }
+            )*)
+        }
+
+        macro_rules! const_fn {
+            ($($({$constness:ident})* fn $i:ident(
+                        $($arg:ident: $argty:ty),*
+            ) -> $ret:ty {
+                $($body:stmt);*
+            })*) => ($(
+                #[inline]
+                fn $i($($arg: $argty),*
+                ) -> $ret {
                     $($body);*
                 }
             )*)

src/unix/linux_like/mod.rs

@@ -1165,8 +1165,10 @@ pub const ARPHRD_IEEE802154: u16 = 804;
 pub const ARPHRD_VOID: u16 = 0xFFFF;
 pub const ARPHRD_NONE: u16 = 0xFFFE;
 
-const fn CMSG_ALIGN(len: usize) -> usize {
-    len + ::mem::size_of::<usize>() - 1 & !(::mem::size_of::<usize>() - 1)
+const_fn! {
+    {const} fn CMSG_ALIGN(len: usize) -> usize {
+        len + ::mem::size_of::<usize>() - 1 & !(::mem::size_of::<usize>() - 1)
+    }
 }
 
 f! {