proc_macro: add #![warn(unreachable_pub)]

library/proc_macro/src/bridge/closure.rs

@@ -3,7 +3,7 @@
 use std::marker::PhantomData;
 
 #[repr(C)]
-pub struct Closure<'a, A, R> {
+pub(super) struct Closure<'a, A, R> {
     call: unsafe extern "C" fn(*mut Env, A) -> R,
     env: *mut Env,
     // Prevent Send and Sync impls. `!Send`/`!Sync` is the usual way of doing
@@ -26,7 +26,7 @@ impl<'a, A, R, F: FnMut(A) -> R> From<&'a mut F> for Closure<'a, A, R> {
 }
 
 impl<'a, A, R> Closure<'a, A, R> {
-    pub fn call(&mut self, arg: A) -> R {
+    pub(super) fn call(&mut self, arg: A) -> R {
         unsafe { (self.call)(self.env, arg) }
     }
 }

library/proc_macro/src/bridge/fxhash.rs

@@ -9,7 +9,7 @@ use std::hash::{BuildHasherDefault, Hasher};
 use std::ops::BitXor;
 
 /// Type alias for a hashmap using the `fx` hash algorithm.
-pub type FxHashMap<K, V> = HashMap<K, V, BuildHasherDefault<FxHasher>>;
+pub(super) type FxHashMap<K, V> = HashMap<K, V, BuildHasherDefault<FxHasher>>;
 
 /// A speedy hash algorithm for use within rustc. The hashmap in alloc by
 /// default uses SipHash which isn't quite as speedy as we want. In the compiler
@@ -23,7 +23,7 @@ pub type FxHashMap<K, V> = HashMap<K, V, BuildHasherDefault<FxHasher>>;
 /// similar or slightly worse than FNV, but the speed of the hash function
 /// itself is much higher because it works on up to 8 bytes at a time.
 #[derive(Default)]
-pub struct FxHasher {
+pub(super) struct FxHasher {
     hash: usize,
 }
 

library/proc_macro/src/bridge/rpc.rs

@@ -67,7 +67,7 @@ macro_rules! rpc_encode_decode {
                 mod tag {
                     #[repr(u8)] enum Tag { $($variant),* }
 
-                    $(pub const $variant: u8 = Tag::$variant as u8;)*
+                    $(pub(crate) const $variant: u8 = Tag::$variant as u8;)*
                 }
 
                 match self {
@@ -89,7 +89,7 @@ macro_rules! rpc_encode_decode {
                 mod tag {
                     #[repr(u8)] enum Tag { $($variant),* }
 
-                    $(pub const $variant: u8 = Tag::$variant as u8;)*
+                    $(pub(crate) const $variant: u8 = Tag::$variant as u8;)*
                 }
 
                 match u8::decode(r, s) {

library/proc_macro/src/bridge/selfless_reify.rs

@@ -44,7 +44,7 @@ macro_rules! define_reify_functions {
         fn $name:ident $(<$($param:ident),*>)?
             for $(extern $abi:tt)? fn($($arg:ident: $arg_ty:ty),*) -> $ret_ty:ty;
     )+) => {
-        $(pub const fn $name<
+        $(pub(super) const fn $name<
             $($($param,)*)?
             F: Fn($($arg_ty),*) -> $ret_ty + Copy
         >(f: F) -> $(extern $abi)? fn($($arg_ty),*) -> $ret_ty {

library/proc_macro/src/lib.rs

@@ -32,6 +32,7 @@
 #![allow(internal_features)]
 #![deny(ffi_unwind_calls)]
 #![warn(rustdoc::unescaped_backticks)]
+#![warn(unreachable_pub)]
 
 #[unstable(feature = "proc_macro_internals", issue = "27812")]
 #[doc(hidden)]