From 56074b5231ceef266a1097ea355f62c951e1b468 Mon Sep 17 00:00:00 2001 From: Amanieu d'Antras Date: Fri, 14 Oct 2022 02:24:58 +0100 Subject: Rewrite implementation of `#[alloc_error_handler]` The new implementation doesn't use weak lang items and instead changes `#[alloc_error_handler]` to an attribute macro just like `#[global_allocator]`. The attribute will generate the `__rg_oom` function which is called by the compiler-generated `__rust_alloc_error_handler`. If no `__rg_oom` function is defined in any crate then the compiler shim will call `__rdl_oom` in the alloc crate which will simply panic. This also fixes link errors with `-C link-dead-code` with `default_alloc_error_handler`: `__rg_oom` was previously defined in the alloc crate and would attempt to reference the `oom` lang item, even if it didn't exist. This worked as long as `__rg_oom` was excluded from linking since it was not called. This is a prerequisite for the stabilization of `default_alloc_error_handler` (#102318). --- library/alloc/src/alloc.rs | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) (limited to 'library/alloc/src/alloc.rs') diff --git a/library/alloc/src/alloc.rs b/library/alloc/src/alloc.rs index 8187517ccfb..8c6663569a5 100644 --- a/library/alloc/src/alloc.rs +++ b/library/alloc/src/alloc.rs @@ -402,19 +402,18 @@ pub use std::alloc::handle_alloc_error; #[allow(unused_attributes)] #[unstable(feature = "alloc_internals", issue = "none")] pub mod __alloc_error_handler { - use crate::alloc::Layout; - - // called via generated `__rust_alloc_error_handler` - - // if there is no `#[alloc_error_handler]` + // called via generated `__rust_alloc_error_handler` if there is no + // `#[alloc_error_handler]`. #[rustc_std_internal_symbol] pub unsafe fn __rdl_oom(size: usize, _align: usize) -> ! { panic!("memory allocation of {size} bytes failed") } - // if there is an `#[alloc_error_handler]` + #[cfg(bootstrap)] #[rustc_std_internal_symbol] pub unsafe fn __rg_oom(size: usize, align: usize) -> ! { + use crate::alloc::Layout; + let layout = unsafe { Layout::from_size_align_unchecked(size, align) }; extern "Rust" { #[lang = "oom"] -- cgit 1.4.1-3-g733a5