Improved support for visibility restrictions

Author: fuine

src/lib.rs

@@ -116,24 +116,12 @@ pub use core::ops::Deref as __Deref;
 #[cfg_attr(feature="nightly", allow_internal_unstable)]
 #[doc(hidden)]
 macro_rules! __lazy_static_internal {
-    ($(#[$attr:meta])* static ref $N:ident : $T:ty = $e:expr; $($t:tt)*) => {
-        __lazy_static_internal!(@PRIV, $(#[$attr])* static ref $N : $T = $e; $($t)*);
-    };
-    ($(#[$attr:meta])* pub(in $pub_in:path) static ref $N:ident : $T:ty = $e:expr; $($t:tt)*) => {
-        __lazy_static_internal!(@PUB_IN, $pub_in, $(#[$attr])* static ref $N : $T = $e; $($t)*);
-    };
-    ($(#[$attr:meta])* pub static ref $N:ident : $T:ty = $e:expr; $($t:tt)*) => {
-        __lazy_static_internal!(@PUB, $(#[$attr])* static ref $N : $T = $e; $($t)*);
-    };
-    (@PUB_IN, $pub_in:path, $(#[$attr:meta])* static ref $N:ident : $T:ty = $e:expr; $($t:tt)*) => {
-        __lazy_static_internal!(@MAKE TY, PUB_IN, $pub_in, $(#[$attr])*, $N);
+    // optional visibility restrictions are wrapped in `()` to allow for
+    // explicitly passing otherwise implicit information about private items
+    ($(#[$attr:meta])* ($($vis:tt)*) static ref $N:ident : $T:ty = $e:expr; $($t:tt)*) => {
+        __lazy_static_internal!(@MAKE TY, $(#[$attr])*, ($($vis)*), $N);
         __lazy_static_internal!(@TAIL, $N : $T = $e);
-        __lazy_static_internal!($($t)*);
-    };
-    (@$VIS:ident, $(#[$attr:meta])* static ref $N:ident : $T:ty = $e:expr; $($t:tt)*) => {
-        __lazy_static_internal!(@MAKE TY, $VIS, $(#[$attr])*, $N);
-        __lazy_static_internal!(@TAIL, $N : $T = $e);
-        __lazy_static_internal!($($t)*);
+        lazy_static!($($t)*);
     };
     (@TAIL, $N:ident : $T:ty = $e:expr) => {
         impl $crate::__Deref for $N {
@@ -159,32 +147,15 @@ macro_rules! __lazy_static_internal {
             }
         }
     };
-    (@MAKE TY, PUB, $(#[$attr:meta])*, $N:ident) => {
+    // `vis` is wrapped in `()` to prevent parsing ambiguity
+    (@MAKE TY, $(#[$attr:meta])*, ($($vis:tt)*), $N:ident) => {
         #[allow(missing_copy_implementations)]
         #[allow(non_camel_case_types)]
         #[allow(dead_code)]
         $(#[$attr])*
-        pub struct $N {__private_field: ()}
+        $($vis)* struct $N {__private_field: ()}
         #[doc(hidden)]
-        pub static $N: $N = $N {__private_field: ()};
-    };
-    (@MAKE TY, PUB_IN, $pub_in:path, $(#[$attr:meta])*, $N:ident) => {
-        #[allow(missing_copy_implementations)]
-        #[allow(non_camel_case_types)]
-        #[allow(dead_code)]
-        $(#[$attr])*
-        pub(in $pub_in) struct $N {__private_field: ()}
-        #[doc(hidden)]
-        pub(in $pub_in) static $N: $N = $N {__private_field: ()};
-    };
-    (@MAKE TY, PRIV, $(#[$attr:meta])*, $N:ident) => {
-        #[allow(missing_copy_implementations)]
-        #[allow(non_camel_case_types)]
-        #[allow(dead_code)]
-        $(#[$attr])*
-        struct $N {__private_field: ()}
-        #[doc(hidden)]
-        static $N: $N = $N {__private_field: ()};
+        $($vis)* static $N: $N = $N {__private_field: ()};
     };
     () => ()
 }
@@ -193,13 +164,14 @@ macro_rules! __lazy_static_internal {
 #[cfg_attr(feature="nightly", allow_internal_unstable)]
 macro_rules! lazy_static {
     ($(#[$attr:meta])* static ref $N:ident : $T:ty = $e:expr; $($t:tt)*) => {
-        __lazy_static_internal!(@PRIV, $(#[$attr])* static ref $N : $T = $e; $($t)*);
-    };
-    ($(#[$attr:meta])* pub (in $pub_in:path) static ref $N:ident : $T:ty = $e:expr; $($t:tt)*) => {
-        __lazy_static_internal!(@PUB_IN, $pub_in, $(#[$attr])* static ref $N : $T = $e; $($t)*);
+        // use `()` to explicitly forward the information about private items
+        __lazy_static_internal!($(#[$attr])* () static ref $N : $T = $e; $($t)*);
     };
     ($(#[$attr:meta])* pub static ref $N:ident : $T:ty = $e:expr; $($t:tt)*) => {
-        __lazy_static_internal!(@PUB, $(#[$attr])* static ref $N : $T = $e; $($t)*);
+        __lazy_static_internal!($(#[$attr])* (pub) static ref $N : $T = $e; $($t)*);
+    };
+    ($(#[$attr:meta])* pub ($($vis:tt)+) static ref $N:ident : $T:ty = $e:expr; $($t:tt)*) => {
+        __lazy_static_internal!($(#[$attr])* (pub ($($vis)+)) static ref $N : $T = $e; $($t)*);
     };
     () => ()
 }

tests/test.rs

@@ -84,16 +84,32 @@ mod visibility {
         static ref BAR: Box<u32> = Box::new(98);
     }
 
+    pub mod inner {
+        lazy_static! {
+            pub(in visibility) static ref BAZ: Box<u32> = Box::new(42);
+            pub(crate) static ref BAG: Box<u32> = Box::new(37);
+            // if uncommented this should cause a compiler error
+            // error: incorrect visibility restriction
+            // pub(nonsense) static ref BIG: Box<u32> = Box::new(6);
+        }
+    }
+
     #[test]
     fn sub_test() {
         assert_eq!(**FOO, 0);
         assert_eq!(**BAR, 98);
+        assert_eq!(**inner::BAZ, 42);
+        assert_eq!(**inner::BAG, 37);
     }
 }
 
 #[test]
 fn test_visibility() {
     assert_eq!(*visibility::FOO, Box::new(0));
+    // if uncommented this should cause a compiler error:
+    // error[E0603]: static `BAZ` is private
+    // assert_eq!(*visibility::inner::BAZ, Box::new(42));
+    assert_eq!(*visibility::inner::BAG, Box::new(37));
 }
 
 // This should not cause a warning about a missing Copy implementation