Update the c_enum macro to take multiple values

Partial cherry pick of a541bf4 ("libc: remove uses of enum as per #4419").

Co-authored-by: mbyx <[email protected]>

Author: tgross35

src/macros.rs

@@ -223,10 +223,24 @@ macro_rules! e {
 ///
 /// See <https://github.com/rust-lang/libc/issues/4419> for more.
 macro_rules! c_enum {
-    (
+    ($(
+        $(#[repr($repr:ty)])?
+        pub enum $ty_name:ident {
+            $($variant:ident $(= $value:expr)?,)+
+        }
+    )+) => {
+        $(c_enum!(@expand;
+            $(#[repr($repr)])?
+            pub enum $ty_name {
+                $($variant $(= $value)?,)+
+            }
+        );)+
+    };
+
+    (@expand;
         $(#[repr($repr:ty)])?
-        enum $ty_name:ident {
-            $($variant:ident $(= $value:literal)?,)+
+        pub enum $ty_name:ident {
+            $($variant:ident $(= $value:expr)?,)+
         }
     ) => {
         pub type $ty_name = c_enum!(@ty $($repr)?);
@@ -237,7 +251,7 @@ macro_rules! c_enum {
     (@one; $_ty_name:ident; $_idx:expr;) => {};
     (
         @one; $ty_name:ident; $default_val:expr;
-        $variant:ident $(= $value:literal)?,
+        $variant:ident $(= $value:expr)?,
         $($tail:tt)*
     ) => {
         pub const $variant: $ty_name = {
@@ -413,7 +427,7 @@ mod tests {
     fn c_enumbasic() {
         // By default, variants get sequential values.
         c_enum! {
-            enum e {
+            pub enum e {
                 VAR0,
                 VAR1,
                 VAR2,
@@ -430,7 +444,7 @@ mod tests {
         // By default, variants get sequential values.
         c_enum! {
             #[repr(u16)]
-            enum e {
+            pub enum e {
                 VAR0,
             }
         }
@@ -442,7 +456,7 @@ mod tests {
     fn c_enumset_value() {
         // Setting an explicit value resets the count.
         c_enum! {
-            enum e {
+            pub enum e {
                 VAR2 = 2,
                 VAR3,
                 VAR4,
@@ -459,7 +473,7 @@ mod tests {
         // C enums always take one more than the previous value, unless set to a specific
         // value. Duplicates are allowed.
         c_enum! {
-            enum e {
+            pub enum e {
                 VAR0,
                 VAR2_0 = 2,
                 VAR3_0,

src/unix/linux_like/linux/mod.rs

@@ -84,7 +84,7 @@ e! {
 }
 
 c_enum! {
-    enum pid_type {
+    pub enum pid_type {
         PIDTYPE_PID,
         PIDTYPE_TGID,
         PIDTYPE_PGID,
@@ -4468,14 +4468,12 @@ pub const RTNLGRP_STATS: c_uint = 0x24;
 
 // linux/cn_proc.h
 c_enum! {
-    enum proc_cn_mcast_op {
+    pub enum proc_cn_mcast_op {
         PROC_CN_MCAST_LISTEN = 1,
         PROC_CN_MCAST_IGNORE = 2,
     }
-}
 
-c_enum! {
-    enum proc_cn_event {
+    pub enum proc_cn_event {
         PROC_EVENT_NONE = 0x00000000,
         PROC_EVENT_FORK = 0x00000001,
         PROC_EVENT_EXEC = 0x00000002,