Auto merge of rust-lang#109507 - Amanieu:panic-oom-payload, r=davidtwco

Report allocation errors as panics

OOM is now reported as a panic but with a custom payload type (`AllocErrorPanicPayload`) which holds the layout that was passed to `handle_alloc_error`.

This should be review one commit at a time:
- The first commit adds `AllocErrorPanicPayload` and changes allocation errors to always be reported as panics.
- The second commit removes `#[alloc_error_handler]` and the `alloc_error_hook` API.

ACP: rust-lang/libs-team#192

Closes rust-lang#51540
Closes rust-lang#51245

Author: bors

example/alloc_example.rs

@@ -1,4 +1,4 @@
-#![feature(start, core_intrinsics, alloc_error_handler)]
+#![feature(start, core_intrinsics)]
 #![no_std]
 
 extern crate alloc;
@@ -22,11 +22,6 @@ fn panic_handler(_: &core::panic::PanicInfo) -> ! {
     core::intrinsics::abort();
 }
 
-#[alloc_error_handler]
-fn alloc_error_handler(_: alloc::alloc::Layout) -> ! {
-    core::intrinsics::abort();
-}
-
 #[start]
 fn main(_argc: isize, _argv: *const *const u8) -> isize {
     let world: Box<&str> = Box::new("Hello World!\0");

src/allocator.rs

@@ -6,7 +6,6 @@ use crate::prelude::*;
 use rustc_ast::expand::allocator::{AllocatorKind, AllocatorTy, ALLOCATOR_METHODS};
 use rustc_codegen_ssa::base::allocator_kind_for_codegen;
 use rustc_session::config::OomStrategy;
-use rustc_span::symbol::sym;
 
 /// Returns whether an allocator shim was created
 pub(crate) fn codegen(
@@ -15,21 +14,14 @@ pub(crate) fn codegen(
     unwind_context: &mut UnwindContext,
 ) -> bool {
     let Some(kind) = allocator_kind_for_codegen(tcx) else { return false };
-    codegen_inner(
-        module,
-        unwind_context,
-        kind,
-        tcx.alloc_error_handler_kind(()).unwrap(),
-        tcx.sess.opts.unstable_opts.oom,
-    );
+    codegen_inner(module, unwind_context, kind, tcx.sess.opts.unstable_opts.oom);
     true
 }
 
 fn codegen_inner(
     module: &mut impl Module,
     unwind_context: &mut UnwindContext,
     kind: AllocatorKind,
-    alloc_error_handler_kind: AllocatorKind,
     oom_strategy: OomStrategy,
 ) {
     let usize_ty = module.target_config().pointer_type();
@@ -71,19 +63,6 @@ fn codegen_inner(
         );
     }
 
-    let sig = Signature {
-        call_conv: module.target_config().default_call_conv,
-        params: vec![AbiParam::new(usize_ty), AbiParam::new(usize_ty)],
-        returns: vec![],
-    };
-    crate::common::create_wrapper_function(
-        module,
-        unwind_context,
-        sig,
-        "__rust_alloc_error_handler",
-        &alloc_error_handler_kind.fn_name(sym::oom),
-    );
-
     let data_id = module.declare_data(OomStrategy::SYMBOL, Linkage::Export, false, false).unwrap();
     let mut data_ctx = DataContext::new();
     data_ctx.set_align(1);