Global.oom -> heap::alloc::oom and explanation fixup

src/vec-alloc.md

@@ -37,10 +37,11 @@ that, we'll need to use the rest of the heap APIs. These basically allow us to
 talk directly to Rust's allocator (jemalloc by default).
 
 We'll also need a way to handle out-of-memory (OOM) conditions. The standard
-library calls the `abort` intrinsic, which just calls an illegal instruction to
-crash the whole program. The reason we abort and don't panic is because
-unwinding can cause allocations to happen, and that seems like a bad thing to do
-when your allocator just came back with "hey I don't have any more memory".
+library calls `std::alloc::oom()`, which in turn calls the the `oom` langitem.
+By default this just aborts the program by executing an illegal cpu instruction.
+The reason we abort and don't panic is because unwinding can cause allocations
+to happen, and that seems like a bad thing to do when your allocator just came
+back with "hey I don't have any more memory".
 
 Of course, this is a bit silly since most platforms don't actually run out of
 memory in a conventional way. Your operating system will probably kill the
@@ -51,15 +52,6 @@ of memory at once (e.g. half the theoretical address space). As such it's
 like the standard library as much as possible, so we'll just kill the whole
 program.
 
-We said we don't want to use intrinsics, so doing exactly what `std` does is
-out. Instead, we'll call `std::process::exit` with some random number.
-
-```rust
-fn oom() {
-    ::std::process::exit(-9999);
-}
-```
-
 Okay, now we can write growing. Roughly, we want to have this logic:
 
 ```text
@@ -165,6 +157,8 @@ such we will guard against this case explicitly.
 Ok with all the nonsense out of the way, let's actually allocate some memory:
 
 ```rust,ignore
+use std::alloc::oom;
+
 fn grow(&mut self) {
     // this is all pretty delicate, so let's say it's all unsafe
     unsafe {

src/vec-final.md

@@ -9,7 +9,7 @@ use std::ptr::{Unique, self};
 use std::mem;
 use std::ops::{Deref, DerefMut};
 use std::marker::PhantomData;
-use std::alloc::{GlobalAlloc, Layout, Global};
+use std::alloc::{GlobalAlloc, Layout, Global, oom};
 
 struct RawVec<T> {
     ptr: Unique<T>,
@@ -46,7 +46,7 @@ impl<T> RawVec<T> {
 
             // If allocate or reallocate fail, oom
             if ptr.is_null() {
-                Global.oom()
+                oom()
             }
 
             self.ptr = Unique::new_unchecked(ptr as *mut _);
@@ -299,12 +299,5 @@ impl<'a, T> Drop for Drain<'a, T> {
     }
 }
 
-/// Abort the process, we're out of memory!
-///
-/// In practice this is probably dead code on most OSes
-fn oom() {
-    ::std::process::exit(-9999);
-}
-
 # fn main() {}
 ```