From 81ebaf27cb4301a833f5a4ba1f4a6e63cfcc32b3 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Sun, 10 Mar 2024 17:12:27 +0100
Subject: [PATCH 1/2] RawVec::into_box: avoid unnecessary intermediate
reference
---
library/alloc/src/raw_vec.rs | 3 +--
tests/ui/hygiene/panic-location.rs | 1 +
tests/ui/hygiene/panic-location.run.stderr | 2 +-
3 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/library/alloc/src/raw_vec.rs b/library/alloc/src/raw_vec.rs
index ace73c0fdaa5e..0ee293db73a93 100644
--- a/library/alloc/src/raw_vec.rs
+++ b/library/alloc/src/raw_vec.rs
@@ -5,7 +5,6 @@ use core::cmp;
use core::hint;
use core::mem::{self, ManuallyDrop, MaybeUninit, SizedTypeProperties};
use core::ptr::{self, NonNull, Unique};
-use core::slice;
#[cfg(not(no_global_oom_handling))]
use crate::alloc::handle_alloc_error;
@@ -192,7 +191,7 @@ impl<T, A: Allocator> RawVec<T, A> {
let me = ManuallyDrop::new(self);
unsafe {
- let slice = slice::from_raw_parts_mut(me.ptr() as *mut MaybeUninit<T>, len);
+ let slice = ptr::slice_from_raw_parts_mut(me.ptr() as *mut MaybeUninit<T>, len);
Box::from_raw_in(slice, ptr::read(&me.alloc))
}
}
diff --git a/tests/ui/hygiene/panic-location.rs b/tests/ui/hygiene/panic-location.rs
index a98960d74b019..b2f9bfe4f9a7a 100644
--- a/tests/ui/hygiene/panic-location.rs
+++ b/tests/ui/hygiene/panic-location.rs
@@ -1,6 +1,7 @@
//@ run-fail
//@ check-run-results
//@ exec-env:RUST_BACKTRACE=0
+//@ normalize-stderr-test ".rs:\d+:\d+" -> ".rs:LL:CC"
//
// Regression test for issue #70963
// The captured stderr from this test reports a location
diff --git a/tests/ui/hygiene/panic-location.run.stderr b/tests/ui/hygiene/panic-location.run.stderr
index ec0ce18c3dfa7..5c1778bc485f9 100644
--- a/tests/ui/hygiene/panic-location.run.stderr
+++ b/tests/ui/hygiene/panic-location.run.stderr
@@ -1,3 +1,3 @@
-thread 'main' panicked at library/alloc/src/raw_vec.rs:26:5:
+thread 'main' panicked at library/alloc/src/raw_vec.rs:LL:CC:
capacity overflow
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
From a7443f554215b76ef1f911b1d6d07b4b7ebbb23c Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Sun, 10 Mar 2024 18:04:03 +0100
Subject: [PATCH 2/2] test into_boxed_slice with custom allocator in Miri
---
.../tests/pass/box-custom-alloc-aliasing.rs | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)
diff --git a/src/tools/miri/tests/pass/box-custom-alloc-aliasing.rs b/src/tools/miri/tests/pass/box-custom-alloc-aliasing.rs
index 541e5f244db08..ada9cf4537547 100644
--- a/src/tools/miri/tests/pass/box-custom-alloc-aliasing.rs
+++ b/src/tools/miri/tests/pass/box-custom-alloc-aliasing.rs
@@ -92,6 +92,8 @@ unsafe impl Allocator for MyAllocator {
}
unsafe fn deallocate(&self, ptr: NonNull<u8>, _layout: Layout) {
+ // Make sure accesses via `self` don't disturb anything.
+ let _val = self.bins[0].top.get();
// Since manually finding the corresponding bin of `ptr` is very expensive,
// doing pointer arithmetics is preferred.
// But this means we access `top` via `ptr` rather than `self`!
@@ -101,22 +103,30 @@ unsafe impl Allocator for MyAllocator {
if self.thread_id == thread_id {
unsafe { (*their_bin).push(ptr) };
} else {
- todo!("Deallocating from another thread")
+ todo!("Deallocating from another thread");
}
+ // Make sure we can also still access this via `self` after the rest is done.
+ let _val = self.bins[0].top.get();
}
}
// Make sure to involve `Box` in allocating these,
// as that's where `noalias` may come from.
-fn v<T, A: Allocator>(t: T, a: A) -> Vec<T, A> {
+fn v1<T, A: Allocator>(t: T, a: A) -> Vec<T, A> {
(Box::new_in([t], a) as Box<[T], A>).into_vec()
}
+fn v2<T, A: Allocator>(t: T, a: A) -> Vec<T, A> {
+ let v = v1(t, a);
+ // There was a bug in `into_boxed_slice` that caused aliasing issues,
+ // so round-trip through that as well.
+ v.into_boxed_slice().into_vec()
+}
fn main() {
assert!(mem::size_of::<MyBin>() <= 128); // if it grows bigger, the trick to access the "header" no longer works
let my_alloc = MyAllocator::new();
- let a = v(1usize, &my_alloc);
- let b = v(2usize, &my_alloc);
+ let a = v1(1usize, &my_alloc);
+ let b = v2(2usize, &my_alloc);
assert_eq!(a[0] + 1, b[0]);
assert_eq!(addr_of!(a[0]).wrapping_add(1), addr_of!(b[0]));
drop((a, b));