Add AbortAdapter allocator adapter

See its documentation for why its useful

Author: Ericson2314

src/liballoc/abort_adapter.rs

@@ -0,0 +1,109 @@
+//! An allocator adapter that blows up by calling `handle_alloc_error` on all errors.
+//!
+//! On one hand, concrete allocator implementations should always be written
+//! without panicking on user error and OOM to give users maximum
+//! flexibility. On the other hand, code that depends on allocation succeeding
+//! should depend on `Alloc<Err=!>` to avoid repetitively handling errors from
+//! which it cannot recover.
+//!
+//! This adapter bridges the gap, effectively allowing `Alloc<Err=!>` to be
+//! implemented by any allocator.
+
+#![unstable(feature = "allocator_api",
+            reason = "the precise API and guarantees it provides may be tweaked \
+                      slightly, especially to possibly take into account the \
+                      types being stored to make room for a future \
+                      tracing garbage collector",
+            issue = "32838")]
+
+use core::usize;
+use core::ptr::NonNull;
+
+use crate::alloc::*;
+
+/// An allocator adapter that blows up by calling `handle_alloc_error` on all errors.
+///
+/// See the [module-level documentation](../../std/abort_adapter/index.html) for more.
+#[derive(Copy, Clone, Debug, Default)]
+pub struct AbortAdapter<Alloc>(pub Alloc);
+
+impl<A: AllocHelper> AllocHelper for AbortAdapter<A> {
+    type Err = !;
+}
+
+unsafe impl<A: Alloc> Alloc for AbortAdapter<A> {
+    unsafe fn alloc(&mut self, layout: Layout) -> Result<NonNull<u8>, Self::Err> {
+        self.0.alloc(layout).or_else(|_| handle_alloc_error(layout))
+    }
+
+    unsafe fn dealloc(&mut self, ptr: NonNull<u8>, layout: Layout) {
+        self.0.dealloc(ptr, layout)
+    }
+
+    fn usable_size(&self, layout: &Layout) -> (usize, usize) {
+        self.0.usable_size(layout)
+    }
+
+    unsafe fn realloc(&mut self,
+                      ptr: NonNull<u8>,
+                      layout: Layout,
+                      new_size: usize) -> Result<NonNull<u8>, Self::Err> {
+        self.0.realloc(ptr, layout, new_size).or_else(|_| handle_alloc_error(layout))
+    }
+
+    unsafe fn alloc_zeroed(&mut self, layout: Layout) -> Result<NonNull<u8>, Self::Err> {
+        self.0.alloc_zeroed(layout).or_else(|_| handle_alloc_error(layout))
+    }
+
+    unsafe fn alloc_excess(&mut self, layout: Layout) -> Result<Excess, Self::Err> {
+        self.0.alloc_excess(layout).or_else(|_| handle_alloc_error(layout))
+    }
+
+    unsafe fn grow_in_place(&mut self,
+                            ptr: NonNull<u8>,
+                            layout: Layout,
+                            new_size: usize) -> Result<(), CannotReallocInPlace> {
+        self.0.grow_in_place(ptr, layout, new_size)
+    }
+
+    unsafe fn shrink_in_place(&mut self,
+                              ptr: NonNull<u8>,
+                              layout: Layout,
+                              new_size: usize) -> Result<(), CannotReallocInPlace> {
+        self.0.shrink_in_place(ptr, layout, new_size)
+    }
+
+    fn alloc_one<T>(&mut self) -> Result<NonNull<T>, Self::Err>
+        where Self: Sized
+    {
+        self.0.alloc_one().or_else(|_| handle_alloc_error(Layout::new::<T>()))
+    }
+
+    unsafe fn dealloc_one<T>(&mut self, ptr: NonNull<T>)
+        where Self: Sized
+    {
+        self.0.dealloc_one(ptr)
+    }
+
+    fn alloc_array<T>(&mut self, n: usize) -> Result<NonNull<T>, Self::Err>
+        where Self: Sized
+    {
+        self.0.alloc_array(n).or_else(|_| handle_alloc_error(Layout::new::<T>()))
+    }
+
+    unsafe fn realloc_array<T>(&mut self,
+                               ptr: NonNull<T>,
+                               n_old: usize,
+                               n_new: usize) -> Result<NonNull<T>, Self::Err>
+        where Self: Sized
+    {
+        self.0.realloc_array(ptr, n_old, n_new)
+            .or_else(|_| handle_alloc_error(Layout::new::<T>()))
+    }
+
+    unsafe fn dealloc_array<T>(&mut self, ptr: NonNull<T>, n: usize) -> Result<(), Self::Err>
+        where Self: Sized
+    {
+        self.0.dealloc_array(ptr, n).or_else(|_| handle_alloc_error(Layout::new::<T>()))
+    }
+}

src/liballoc/lib.rs

@@ -112,6 +112,7 @@
 #![feature(maybe_uninit_extra, maybe_uninit_slice, maybe_uninit_array)]
 #![feature(alloc_layout_extra)]
 #![feature(try_trait)]
+#![feature(never_type)]
 
 // Allow testing this library
 
@@ -128,6 +129,7 @@ mod macros;
 // Heaps provided for low-level allocation strategies
 
 pub mod alloc;
+pub mod abort_adapter;
 
 // Primitive types using the heaps above
 

src/liballoc/raw_vec.rs

@@ -422,7 +422,8 @@ impl<T, A: Alloc<Err = AllocErr>> RawVec<T, A> {
         -> Result<usize, CollectionAllocErr> {
 
         // Nothing we can really do about these checks :(
-        let required_cap = used_cap.checked_add(needed_extra_cap).ok_or(CollectionAllocErr::CapacityOverflow)?;
+        let required_cap = used_cap.checked_add(needed_extra_cap)
+            .ok_or(CollectionAllocErr::CapacityOverflow)?;
         // Cannot overflow, because `cap <= isize::MAX`, and type of `cap` is `usize`.
         let double_cap = self.cap * 2;
         // `double_cap` guarantees exponential growth.
@@ -651,10 +652,12 @@ impl<T, A: Alloc<Err = AllocErr>> RawVec<T, A> {
 
             // Nothing we can really do about these checks :(
             let new_cap = match strategy {
-                Exact => used_cap.checked_add(needed_extra_cap).ok_or(CollectionAllocErr::CapacityOverflow)?,
+                Exact => used_cap.checked_add(needed_extra_cap)
+                    .ok_or(CollectionAllocErr::CapacityOverflow)?,
                 Amortized => self.amortized_new_size(used_cap, needed_extra_cap)?,
             };
-            let new_layout = Layout::array::<T>(new_cap).map_err(|_| CollectionAllocErr::CapacityOverflow)?;
+            let new_layout = Layout::array::<T>(new_cap)
+                .map_err(|_| CollectionAllocErr::CapacityOverflow)?;
 
             alloc_guard(new_layout.size())?;