Re-introduce FnBox

Author: bjorn3

patches/0015-Remove-usage-of-unsized-locals.patch

@@ -44,53 +44,16 @@ index f6dee7c..0c6a8c0 100644
  #[unstable(feature = "coerce_unsized", issue = "27732")]
  impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<Box<U>> for Box<T> {}
 
-diff --git a/src/libstd/sys_common/at_exit_imp.rs b/src/libstd/sys_common/at_exit_imp.rs
-index 1181b86..20f9251 100644
---- a/src/libstd/sys_common/at_exit_imp.rs
-+++ b/src/libstd/sys_common/at_exit_imp.rs
-@@ -38,6 +38,7 @@ unsafe fn init() -> bool {
-     true
- }
- 
-+/*
- pub fn cleanup() {
-     for i in 1..=ITERS {
-         unsafe {
-@@ -60,6 +61,7 @@ pub fn cleanup() {
-         }
-     }
- }
-+*/
- 
- pub fn push(f: Box<dyn FnOnce()>) -> bool {
-     unsafe {
-diff --git a/src/libstd/sys_common/mod.rs b/src/libstd/sys_common/mod.rs
-index 6260c3b..611ed7e 100644
---- a/src/libstd/sys_common/mod.rs
-+++ b/src/libstd/sys_common/mod.rs
-@@ -127,7 +127,6 @@ pub fn cleanup() {
-     CLEANUP.call_once(|| unsafe {
-         sys::args::cleanup();
-         sys::stack_overflow::cleanup();
--        at_exit_imp::cleanup();
-     });
- }
- 
 diff --git a/src/libstd/sys_common/thread.rs b/src/libstd/sys_common/thread.rs
 index b2142e7..718bb1c 100644
 --- a/src/libstd/sys_common/thread.rs
 +++ b/src/libstd/sys_common/thread.rs
-@@ -6,12 +6,7 @@ use crate::sys::thread as imp;
+@@ -6,7 +6,7 @@ pub unsafe fn start_thread(main: *mut u8) {
+     let _handler = stack_overflow::Handler::new();
 
- #[allow(dead_code)]
- pub unsafe fn start_thread(main: *mut u8) {
--    // Next, set up our stack overflow handler which may get triggered if we run
--    // out of stack.
--    let _handler = stack_overflow::Handler::new();
--
--    // Finally, let's run some code.
+     // Finally, let's run some code.
 -    Box::from_raw(main as *mut Box<dyn FnOnce()>)()
-+    panic!("Threads are not yet supported, because cranelift doesn't support atomics.");
++    Box::from_raw(main as *mut Box<dyn FnBox()>)()
  }
 
  pub fn min_stack() -> usize {
@@ -101,7 +64,7 @@ index f4a1783..362b537 100644
 @@ -40,5 +40,7 @@ impl Thread {
      // unsafe: see thread::Builder::spawn_unchecked for safety requirements
      pub unsafe fn new(stack: usize, p: Box<dyn FnOnce()>) -> io::Result<Thread> {
-+        panic!("Threads are not yet supported, because cranelift doesn't support atomics.");
++        panic!("Warning: Threads are not yet fully supported, because cranelift doesn't support atomics.");
 +
          let p = box p;
          let mut native: libc::pthread_t = mem::zeroed();

patches/0018-Add-FnBox-back.patch

@@ -0,0 +1,173 @@
+From 8617310c3c9e192080df6a0c7b4835d3f02e27b9 Mon Sep 17 00:00:00 2001
+From: bjorn3 <[email protected]>
+Date: Fri, 1 Nov 2019 20:58:30 +0100
+Subject: [PATCH] Add FnBox back
+
+---
+ src/liballoc/boxed.rs                | 13 +++++++++++++
+ src/libstd/prelude/v1.rs             |  2 +-
+ src/libstd/sys/cloudabi/thread.rs    |  2 +-
+ src/libstd/sys/hermit/thread.rs      |  4 ++--
+ src/libstd/sys/unix/thread.rs        |  4 ++--
+ src/libstd/sys_common/at_exit_imp.rs |  6 +++---
+ src/libstd/sys_common/mod.rs         |  2 +-
+ src/libstd/sys_common/thread.rs      |  2 +-
+ src/libstd/thread/mod.rs             |  2 +-
+ 9 files changed, 25 insertions(+), 12 deletions(-)
+
+diff --git a/src/liballoc/boxed.rs b/src/liballoc/boxed.rs
+index ef9b648..e32b870 100644
+--- a/src/liballoc/boxed.rs
++++ b/src/liballoc/boxed.rs
+@@ -1079,3 +1079,16 @@ impl<F: ?Sized + Future + Unpin> Future for Box<F> {
+         F::poll(Pin::new(&mut *self), cx)
+     }
+ }
++
++#[stable(feature = "rust1", since = "1.0.0")]
++pub trait FnBox<A>: FnOnce<A> {
++    #[stable(feature = "rust1", since = "1.0.0")]
++    extern "rust-call" fn call_box(self: Box<Self>, args: A) -> Self::Output;
++}
++
++#[stable(feature = "rust1", since = "1.0.0")]
++impl<A, F: FnOnce<A>> FnBox<A> for F {
++    extern "rust-call" fn call_box(self: Box<Self>, args: A) -> Self::Output {
++        <F as FnOnce<A>>::call_once(*self, args)
++    }
++}
+diff --git a/src/libstd/prelude/v1.rs b/src/libstd/prelude/v1.rs
+index 3e4cf91..1f50eb3 100644
+--- a/src/libstd/prelude/v1.rs
++++ b/src/libstd/prelude/v1.rs
+@@ -94,6 +94,6 @@ pub use core::prelude::v1::{
+ #[stable(feature = "rust1", since = "1.0.0")]
+ #[doc(no_inline)]
+-pub use crate::boxed::Box;
++pub use crate::boxed::{Box, FnBox};
+ #[stable(feature = "rust1", since = "1.0.0")]
+ #[doc(no_inline)]
+ pub use crate::string::{String, ToString};
+diff --git a/src/libstd/sys/cloudabi/thread.rs b/src/libstd/sys/cloudabi/thread.rs
+index 240b6ea..6f71c6b 100644
+--- a/src/libstd/sys/cloudabi/thread.rs
++++ b/src/libstd/sys/cloudabi/thread.rs
+@@ -21,7 +21,7 @@ unsafe impl Sync for Thread {}
+ 
+ impl Thread {
+     // unsafe: see thread::Builder::spawn_unchecked for safety requirements
+-    pub unsafe fn new(stack: usize, p: Box<dyn FnOnce()>) -> io::Result<Thread> {
++    pub unsafe fn new(stack: usize, p: Box<dyn FnBox()>) -> io::Result<Thread> {
+         let p = box p;
+         let mut native: libc::pthread_t = mem::zeroed();
+         let mut attr: libc::pthread_attr_t = mem::zeroed();
+diff --git a/src/libstd/sys/hermit/thread.rs b/src/libstd/sys/hermit/thread.rs
+index 99a9c83..b8bc392 100644
+--- a/src/libstd/sys/hermit/thread.rs
++++ b/src/libstd/sys/hermit/thread.rs
+@@ -44,9 +44,9 @@ unsafe impl Sync for Thread {}
+ pub const DEFAULT_MIN_STACK_SIZE: usize = 262144;
+ 
+ impl Thread {
+     pub unsafe fn new_with_coreid(
+         _stack: usize,
+-        p: Box<dyn FnOnce()>,
++        p: Box<dyn FnBox()>,
+         core_id: isize,
+     ) -> io::Result<Thread> {
+         let p = box p;
+@@ -67,7 +67,7 @@ impl Thread {
+         }
+     }
+ 
+-    pub unsafe fn new(stack: usize, p: Box<dyn FnOnce()>) -> io::Result<Thread> {
++    pub unsafe fn new(stack: usize, p: Box<dyn FnBox()>) -> io::Result<Thread> {
+         Thread::new_with_coreid(stack, p, -1 /* = no specific core */)
+     }
+ 
+diff --git a/src/libstd/sys/unix/thread.rs b/src/libstd/sys/unix/thread.rs
+index 143cf2f..a6e8faf 100644
+--- a/src/libstd/sys/unix/thread.rs
++++ b/src/libstd/sys/unix/thread.rs
+@@ -38,8 +38,8 @@ unsafe fn pthread_attr_setstacksize(_attr: *mut libc::pthread_attr_t,
+ 
+ impl Thread {
+     // unsafe: see thread::Builder::spawn_unchecked for safety requirements
+-    pub unsafe fn new(stack: usize, p: Box<dyn FnOnce()>) -> io::Result<Thread> {
++    pub unsafe fn new(stack: usize, p: Box<dyn FnBox()>) -> io::Result<Thread> {
+         panic!("Warning: Threads are not yet fully supported, because cranelift doesn't support atomics.");
+ 
+         let p = box p;
+         let mut native: libc::pthread_t = mem::zeroed();
+diff --git a/src/libstd/sys_common/at_exit_imp.rs b/src/libstd/sys_common/at_exit_imp.rs
+index cdb72ee..e523333 100644
+--- a/src/libstd/sys_common/at_exit_imp.rs
++++ b/src/libstd/sys_common/at_exit_imp.rs
+@@ -6,7 +6,7 @@ use crate::mem;
+ use crate::ptr;
+ use crate::sys_common::mutex::Mutex;
+ 
+-type Queue = Vec<Box<dyn FnOnce()>>;
++type Queue = Vec<Box<dyn FnBox()>>;
+ 
+ // NB these are specifically not types from `std::sync` as they currently rely
+ // on poisoning and this module needs to operate at a lower level than requiring
+@@ -53,14 +53,14 @@ pub fn cleanup() {
+                 let queue: Box<Queue> = Box::from_raw(queue);
+                 for to_run in *queue {
+                     // We are not holding any lock, so reentrancy is fine.
+-                    to_run();
++                    to_run.call_box(());
+                 }
+             }
+         }
+     }
+ }
+ 
+-pub fn push(f: Box<dyn FnOnce()>) -> bool {
++pub fn push(f: Box<dyn FnBox()>) -> bool {
+     unsafe {
+         let _guard = LOCK.lock();
+         if init() {
+diff --git a/src/libstd/sys_common/mod.rs b/src/libstd/sys_common/mod.rs
+index 7a0bcd0..668bef2 100644
+--- a/src/libstd/sys_common/mod.rs
++++ b/src/libstd/sys_common/mod.rs
+@@ -113,7 +113,7 @@ pub trait FromInner<Inner> {
+ /// closure will be run once the main thread exits. Returns `Err` to indicate
+ /// that the closure could not be registered, meaning that it is not scheduled
+ /// to be run.
+-pub fn at_exit<F: FnOnce() + Send + 'static>(f: F) -> Result<(), ()> {
++pub fn at_exit<F: FnBox() + Send + 'static>(f: F) -> Result<(), ()> {
+     if at_exit_imp::push(Box::new(f)) { Ok(()) } else { Err(()) }
+ }
+ 
+diff --git a/src/libstd/sys_common/thread.rs b/src/libstd/sys_common/thread.rs
+index c638be9..5c18a18 100644
+--- a/src/libstd/sys_common/thread.rs
++++ b/src/libstd/sys_common/thread.rs
+@@ -10,7 +10,7 @@ pub unsafe fn start_thread(main: *mut u8) {
+     let _handler = stack_overflow::Handler::new();
+ 
+     // Finally, let's run some code.
+-    Box::from_raw(main as *mut Box<dyn FnBox()>)()
++    Box::from_raw(main as *mut Box<dyn FnBox()>).call_box(())
+ }
+ 
+ pub fn min_stack() -> usize {
+diff --git a/src/libstd/thread/mod.rs b/src/libstd/thread/mod.rs
+index 0ffa6ac..4a3e3d6 100644
+--- a/src/libstd/thread/mod.rs
++++ b/src/libstd/thread/mod.rs
+@@ -485,7 +485,7 @@ impl Builder {
+             // returning.
+             native: Some(imp::Thread::new(
+                 stack_size,
+-                mem::transmute::<Box<dyn FnOnce() + 'a>, Box<dyn FnOnce() + 'static>>(Box::new(
++                mem::transmute::<Box<dyn FnBox() + 'a>, Box<dyn FnBox() + 'static>>(Box::new(
+                     main,
+                 )),
+             )?),
+-- 
+2.20.1
+