Auto merge of #28306 - alexcrichton:less-rt, r=brson

This commit does some refactoring to make almost all of the `std::rt` private.
Specifically, the following items are no longer part of its API:

* DEFAULT_ERROR_CODE
* backtrace
* unwind
* args
* at_exit
* cleanup
* heap (this is just alloc::heap)
* min_stack
* util

The module is now tagged as `#[doc(hidden)]` as the only purpose it's serve is
an entry point for the `panic!` macro via the `begin_unwind` and
`begin_unwind_fmt` reexports.

Author: bors

src/doc/nomicon/destructors.md

@@ -26,13 +26,16 @@ this is totally fine.
 For instance, a custom implementation of `Box` might write `Drop` like this:
 
 ```rust
-#![feature(heap_api, core_intrinsics, unique)]
+#![feature(alloc, heap_api, core_intrinsics, unique)]
+
+extern crate alloc;
 
-use std::rt::heap;
 use std::ptr::Unique;
 use std::intrinsics::drop_in_place;
 use std::mem;
 
+use alloc::heap;
+
 struct Box<T>{ ptr: Unique<T> }
 
 impl<T> Drop for Box<T> {
@@ -45,6 +48,7 @@ impl<T> Drop for Box<T> {
         }
     }
 }
+# fn main() {}
 ```
 
 and this works fine because when Rust goes to drop the `ptr` field it just sees
@@ -54,13 +58,16 @@ use-after-free the `ptr` because when drop exits, it becomes inacessible.
 However this wouldn't work:
 
 ```rust
-#![feature(heap_api, core_intrinsics, unique)]
+#![feature(alloc, heap_api, core_intrinsics, unique)]
+
+extern crate alloc;
 
-use std::rt::heap;
 use std::ptr::Unique;
 use std::intrinsics::drop_in_place;
 use std::mem;
 
+use alloc::heap;
+
 struct Box<T>{ ptr: Unique<T> }
 
 impl<T> Drop for Box<T> {
@@ -87,6 +94,7 @@ impl<T> Drop for SuperBox<T> {
         }
     }
 }
+# fn main() {}
 ```
 
 After we deallocate the `box`'s ptr in SuperBox's destructor, Rust will
@@ -129,13 +137,16 @@ The classic safe solution to overriding recursive drop and allowing moving out
 of Self during `drop` is to use an Option:
 
 ```rust
-#![feature(heap_api, core_intrinsics, unique)]
+#![feature(alloc, heap_api, core_intrinsics, unique)]
+
+extern crate alloc;
 
-use std::rt::heap;
 use std::ptr::Unique;
 use std::intrinsics::drop_in_place;
 use std::mem;
 
+use alloc::heap;
+
 struct Box<T>{ ptr: Unique<T> }
 
 impl<T> Drop for Box<T> {
@@ -165,6 +176,7 @@ impl<T> Drop for SuperBox<T> {
         }
     }
 }
+# fn main() {}
 ```
 
 However this has fairly odd semantics: you're saying that a field that *should*

src/doc/nomicon/vec-alloc.md

@@ -9,7 +9,7 @@ This is perfectly fine because we already have `cap == 0` as our sentinel for no
 allocation. We don't even need to handle it specially in almost any code because
 we usually need to check if `cap > len` or `len > 0` anyway. The traditional
 Rust value to put here is `0x01`. The standard library actually exposes this
-as `std::rt::heap::EMPTY`. There are quite a few places where we'll
+as `alloc::heap::EMPTY`. There are quite a few places where we'll
 want to use `heap::EMPTY` because there's no real allocation to talk about but
 `null` would make the compiler do bad things.
 
@@ -20,11 +20,12 @@ the `heap` API anyway, so let's just get that dependency over with.
 So:
 
 ```rust,ignore
-#![feature(heap_api)]
+#![feature(alloc, heap_api)]
 
-use std::rt::heap::EMPTY;
 use std::mem;
 
+use alloc::heap::EMPTY;
+
 impl<T> Vec<T> {
     fn new() -> Self {
         assert!(mem::size_of::<T>() != 0, "We're not ready to handle ZSTs");

src/doc/nomicon/vec-final.md

@@ -2,17 +2,16 @@
 
 ```rust
 #![feature(unique)]
-#![feature(heap_api)]
+#![feature(alloc, heap_api)]
+
+extern crate alloc;
 
 use std::ptr::{Unique, self};
-use std::rt::heap;
 use std::mem;
 use std::ops::{Deref, DerefMut};
 use std::marker::PhantomData;
 
-
-
-
+use alloc::heap;
 
 struct RawVec<T> {
     ptr: Unique<T>,

src/libarena/lib.rs

@@ -49,7 +49,8 @@ use std::marker;
 use std::mem;
 use std::ptr;
 use std::rc::Rc;
-use std::rt::heap::{allocate, deallocate};
+
+use alloc::heap::{allocate, deallocate};
 
 // The way arena uses arrays is really deeply awful. The arrays are
 // allocated, and have capacities reserved, but the fill for the array

src/liblog/lib.rs

@@ -174,7 +174,6 @@
 #![feature(box_syntax)]
 #![feature(const_fn)]
 #![feature(iter_cmp)]
-#![feature(rt)]
 #![feature(staged_api)]
 #![feature(static_mutex)]
 
@@ -185,7 +184,6 @@ use std::io::prelude::*;
 use std::mem;
 use std::env;
 use std::ptr;
-use std::rt;
 use std::slice;
 use std::sync::{Once, StaticMutex};
 
@@ -292,7 +290,6 @@ pub fn log(level: u32, loc: &'static LogLocation, args: fmt::Arguments) {
         let _g = LOCK.lock();
         match FILTER as usize {
             0 => {}
-            1 => panic!("cannot log after main thread has exited"),
             n => {
                 let filter = mem::transmute::<_, &String>(n);
                 if !args.to_string().contains(filter) {
@@ -385,9 +382,6 @@ pub fn mod_enabled(level: u32, module: &str) -> bool {
     let _g = LOCK.lock();
     unsafe {
         assert!(DIRECTIVES as usize != 0);
-        assert!(DIRECTIVES as usize != 1,
-                "cannot log after the main thread has exited");
-
         enabled(level, module, (*DIRECTIVES).iter())
     }
 }
@@ -442,19 +436,6 @@ fn init() {
 
         assert!(DIRECTIVES.is_null());
         DIRECTIVES = Box::into_raw(box directives);
-
-        // Schedule the cleanup for the globals for when the runtime exits.
-        let _ = rt::at_exit(move || {
-            let _g = LOCK.lock();
-            assert!(!DIRECTIVES.is_null());
-            let _directives = Box::from_raw(DIRECTIVES);
-            DIRECTIVES = 1 as *mut _;
-
-            if !FILTER.is_null() {
-                let _filter = Box::from_raw(FILTER);
-                FILTER = 1 as *mut _;
-            }
-        });
     }
 }
 

src/libstd/collections/hash/table.rs

@@ -8,23 +8,20 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use self::BucketState::*;
+use alloc::heap::{allocate, deallocate, EMPTY};
 
-use clone::Clone;
 use cmp;
 use hash::{Hash, Hasher};
-use iter::{Iterator, ExactSizeIterator};
-use marker::{Copy, Send, Sync, Sized, self};
+use marker;
 use mem::{align_of, size_of};
 use mem;
 use num::wrapping::OverflowingOps;
-use ops::{Deref, DerefMut, Drop};
-use option::Option;
-use option::Option::{Some, None};
+use ops::{Deref, DerefMut};
 use ptr::{self, Unique};
-use rt::heap::{allocate, deallocate, EMPTY};
 use collections::hash_state::HashState;
 
+use self::BucketState::*;
+
 const EMPTY_BUCKET: u64 = 0;
 
 /// The raw hashtable, providing safe-ish access to the unzipped and highly

src/libstd/io/lazy.rs

@@ -12,8 +12,8 @@ use prelude::v1::*;
 
 use cell::Cell;
 use ptr;
-use rt;
 use sync::{StaticMutex, Arc};
+use sys_common;
 
 pub struct Lazy<T> {
     lock: StaticMutex,
@@ -51,7 +51,7 @@ impl<T: Send + Sync + 'static> Lazy<T> {
         // `Arc` allocation in our own internal box (it will get deallocated by
         // the at exit handler). Otherwise we just return the freshly allocated
         // `Arc`.
-        let registered = rt::at_exit(move || {
+        let registered = sys_common::at_exit(move || {
             let g = self.lock.lock();
             let ptr = self.ptr.get();
             self.ptr.set(1 as *mut _);

src/libstd/panicking.rs

@@ -13,9 +13,10 @@ use io::prelude::*;
 
 use any::Any;
 use cell::RefCell;
-use rt::{backtrace, unwind};
 use sys::stdio::Stderr;
+use sys_common::backtrace;
 use sys_common::thread_info;
+use sys_common::unwind;
 
 thread_local! {
     pub static LOCAL_STDERR: RefCell<Option<Box<Write + Send>>> = {

src/libstd/process.rs

@@ -582,7 +582,7 @@ impl Child {
 /// to run.
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn exit(code: i32) -> ! {
-    ::rt::cleanup();
+    ::sys_common::cleanup();
     ::sys::os::exit(code)
 }
 

src/libstd/rt.rs

@@ -0,0 +1,65 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! Runtime services
+//!
+//! The `rt` module provides a narrow set of runtime services,
+//! including the global heap (exported in `heap`) and unwinding and
+//! backtrace support. The APIs in this module are highly unstable,
+//! and should be considered as private implementation details for the
+//! time being.
+
+#![unstable(feature = "rt",
+            reason = "this public module should not exist and is highly likely \
+                      to disappear",
+            issue = "0")]
+#![doc(hidden)]
+
+use borrow::ToOwned;
+use mem;
+use sys;
+use sys_common::thread_info::{self, NewThread};
+use sys_common;
+use thread::{self, Thread};
+
+// Reexport some of our utilities which are expected by other crates.
+pub use sys_common::unwind::{begin_unwind, begin_unwind_fmt};
+
+#[cfg(not(test))]
+#[lang = "start"]
+fn lang_start(main: *const u8, argc: isize, argv: *const *const u8) -> isize {
+    sys::init();
+
+    let failed = unsafe {
+        let main_guard = sys::thread::guard::init();
+        sys::stack_overflow::init();
+
+        // Next, set up the current Thread with the guard information we just
+        // created. Note that this isn't necessary in general for new threads,
+        // but we just do this to name the main thread and to give it correct
+        // info about the stack bounds.
+        let thread: Thread = NewThread::new(Some("<main>".to_owned()));
+        thread_info::set(main_guard, thread);
+
+        // Store our args if necessary in a squirreled away location
+        sys_common::args::init(argc, argv);
+
+        // Let's run some code!
+        let res = thread::catch_panic(mem::transmute::<_, fn()>(main));
+        sys_common::cleanup();
+        res.is_err()
+    };
+
+    if failed {
+        101
+    } else {
+        0
+    }
+}