Auto merge of #52191 - SimonSapin:alloc_error_handler, r=alexcrichton

Implement #[alloc_error_handler]

This to-be-stable attribute is equivalent to `#[lang = "oom"]`. It is required when using the `alloc` crate without the `std` crate. It is called by `handle_alloc_error`, which is in turned called by "infallible" allocations APIs such as `Vec::push`.

2 files changed, 5 insertions, 3 deletions

diff --git a/src/libstd/alloc.rs b/src/libstd/alloc.rs
index f6cecbea11f..8db365cd21d 100644
--- a/src/libstd/alloc.rs
+++ b/src/libstd/alloc.rs
@@ -125,9 +125,10 @@ fn default_alloc_error_hook(layout: Layout) {
 
 #[cfg(not(test))]
 #[doc(hidden)]
-#[lang = "oom"]
+#[cfg_attr(stage0, lang = "oom")]
+#[cfg_attr(not(stage0), alloc_error_handler)]
 #[unstable(feature = "alloc_internals", issue = "0")]
-pub extern fn rust_oom(layout: Layout) -> ! {
+pub fn rust_oom(layout: Layout) -> ! {
     let hook = HOOK.load(Ordering::SeqCst);
     let hook: fn(Layout) = if hook.is_null() {
         default_alloc_error_hook
diff --git a/src/libstd/lib.rs b/src/libstd/lib.rs
index d73cb1f8349..fec14b8d67d 100644
--- a/src/libstd/lib.rs
+++ b/src/libstd/lib.rs
@@ -233,8 +233,9 @@
 // std is implemented with unstable features, many of which are internal
 // compiler details that will never be stable
 #![feature(alloc)]
-#![feature(allocator_api)]
+#![feature(alloc_error_handler)]
 #![feature(alloc_system)]
+#![feature(allocator_api)]
 #![feature(allocator_internals)]
 #![feature(allow_internal_unsafe)]
 #![feature(allow_internal_unstable)]