Adjust the f! macro to be more flexible

Currently this only matches `$body` if every line ends with a semicolon.
Make this simpler by just using the `block` matcher.

Additionally, allow a trailing comma.

(backport <rust-lang#4107>)
(cherry picked from commit 0ac42fd)

Author: tgross35

src/macros.rs

@@ -203,95 +203,83 @@ cfg_if! {
         macro_rules! f {
             ($(
                 $(#[$attr:meta])*
-                pub $({$constness:ident})* fn $i:ident($($arg:ident: $argty:ty),*) -> $ret:ty {
-                    $($body:stmt);*
-                }
+                pub $({$constness:ident})* fn $i:ident($($arg:ident: $argty:ty),* $(,)?) -> $ret:ty
+                    $body:block
             )*) => ($(
                 #[inline]
                 $(#[$attr])*
-                pub $($constness)* unsafe extern fn $i($($arg: $argty),*) -> $ret {
-                    $($body);*
-                }
+                pub $($constness)* unsafe extern fn $i($($arg: $argty),*) -> $ret
+                    $body
             )*)
         }
 
         /// Define a safe function that is const as long as `const-extern-fn` is enabled.
         macro_rules! safe_f {
             ($(
                 $(#[$attr:meta])*
-                pub $({$constness:ident})* fn $i:ident($($arg:ident: $argty:ty),*) -> $ret:ty {
-                    $($body:stmt);*
-                }
+                pub $({$constness:ident})* fn $i:ident($($arg:ident: $argty:ty),* $(,)?) -> $ret:ty
+                    $body:block
             )*) => ($(
                 #[inline]
                 $(#[$attr])*
-                pub $($constness)* extern fn $i($($arg: $argty),*) -> $ret {
-                    $($body);*
-                }
+                pub $($constness)* extern fn $i($($arg: $argty),*) -> $ret
+                    $body
             )*)
         }
 
         /// A nonpublic function that is const as long as `const-extern-fn` is enabled.
         macro_rules! const_fn {
             ($(
                 $(#[$attr:meta])*
-                $({$constness:ident})* fn $i:ident($($arg:ident: $argty:ty),*) -> $ret:ty {
-                    $($body:stmt);*
-                }
+                $({$constness:ident})* fn $i:ident($($arg:ident: $argty:ty),* $(,)?) -> $ret:ty
+                    $body:block
             )*) => ($(
                 #[inline]
                 $(#[$attr])*
-                $($constness)* fn $i($($arg: $argty),*) -> $ret {
-                    $($body);*
-                }
+                $($constness)* fn $i($($arg: $argty),*) -> $ret
+                    $body
             )*)
         }
     } else {
         /// Define an `unsafe` function that is const as long as `const-extern-fn` is enabled.
         macro_rules! f {
             ($(
                 $(#[$attr:meta])*
-                pub $({$constness:ident})* fn $i:ident($($arg:ident: $argty:ty),*) -> $ret:ty {
-                    $($body:stmt);*
-                }
+                pub $({$constness:ident})* fn $i:ident($($arg:ident: $argty:ty),* $(,)?) -> $ret:ty
+                    $body:block
             )*) => ($(
                 #[inline]
                 $(#[$attr])*
-                pub unsafe extern fn $i($($arg: $argty),*) -> $ret {
-                    $($body);*
-                }
+                pub unsafe extern fn $i($($arg: $argty),*) -> $ret
+                    $body
             )*)
         }
 
         /// Define a safe function that is const as long as `const-extern-fn` is enabled.
         macro_rules! safe_f {
             ($(
                 $(#[$attr:meta])*
-                pub $({$constness:ident})* fn $i:ident($($arg:ident: $argty:ty),*) -> $ret:ty {
-                    $($body:stmt);*
-                }
+                pub $({$constness:ident})* fn $i:ident($($arg:ident: $argty:ty),* $(,)?) -> $ret:ty
+                    $body:block
             )*) => ($(
                 #[inline]
                 $(#[$attr])*
-                pub extern fn $i($($arg: $argty),*) -> $ret {
-                    $($body);*
-                }
+                pub extern fn $i($($arg: $argty),*) -> $ret
+                    $body
             )*)
         }
 
         /// A nonpublic function that is const as long as `const-extern-fn` is enabled.
         macro_rules! const_fn {
             ($(
                 $(#[$attr:meta])*
-                $({$constness:ident})* fn $i:ident($($arg:ident: $argty:ty),*) -> $ret:ty {
-                    $($body:stmt);*
-                }
+                $({$constness:ident})* fn $i:ident($($arg:ident: $argty:ty),* $(,)?) -> $ret:ty
+                    $body:block
             )*) => ($(
                 #[inline]
                 $(#[$attr])*
-                fn $i($($arg: $argty),*) -> $ret {
-                    $($body);*
-                }
+                fn $i($($arg: $argty),*) -> $ret
+                    $body
             )*)
         }
     }