From 698f8c2f01ea549d77d7dc3338a12e04c11057b9 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 17 Apr 2024 14:02:58 +0200 Subject: Adding upstream version 1.64.0+dfsg1. Signed-off-by: Daniel Baumann --- library/alloc/tests/thin_box.rs | 262 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 262 insertions(+) create mode 100644 library/alloc/tests/thin_box.rs (limited to 'library/alloc/tests/thin_box.rs') diff --git a/library/alloc/tests/thin_box.rs b/library/alloc/tests/thin_box.rs new file mode 100644 index 000000000..368aa564f --- /dev/null +++ b/library/alloc/tests/thin_box.rs @@ -0,0 +1,262 @@ +use core::fmt::Debug; +use core::mem::size_of; +use std::boxed::ThinBox; + +#[test] +fn want_niche_optimization() { + fn uses_niche() -> bool { + size_of::<*const ()>() == size_of::>>() + } + + trait Tr {} + assert!(uses_niche::()); + assert!(uses_niche::<[i32]>()); + assert!(uses_niche::()); +} + +#[test] +fn want_thin() { + fn is_thin() -> bool { + size_of::<*const ()>() == size_of::>() + } + + trait Tr {} + assert!(is_thin::()); + assert!(is_thin::<[i32]>()); + assert!(is_thin::()); +} + +#[allow(dead_code)] +fn assert_covariance() { + fn thin_box<'new>(b: ThinBox<[&'static str]>) -> ThinBox<[&'new str]> { + b + } +} + +#[track_caller] +fn verify_aligned(ptr: *const T) { + // Use `black_box` to attempt to obscure the fact that we're calling this + // function on pointers that come from box/references, which the compiler + // would otherwise realize is impossible (because it would mean we've + // already executed UB). + // + // That is, we'd *like* it to be possible for the asserts in this function + // to detect brokenness in the ThinBox impl. + // + // It would probably be better if we instead had these as debug_asserts + // inside `ThinBox`, prior to the point where we do the UB. Anyway, in + // practice these checks are mostly just smoke-detectors for an extremely + // broken `ThinBox` impl, since it's an extremely subtle piece of code. + let ptr = core::hint::black_box(ptr); + let align = core::mem::align_of::(); + assert!( + (ptr.addr() & (align - 1)) == 0 && !ptr.is_null(), + "misaligned ThinBox data; valid pointers to `{}` should be aligned to {align}: {ptr:p}", + core::any::type_name::(), + ); +} + +#[track_caller] +fn check_thin_sized(make: impl FnOnce() -> T) { + let value = make(); + let boxed = ThinBox::new(value.clone()); + let val = &*boxed; + verify_aligned(val as *const T); + assert_eq!(val, &value); +} + +#[track_caller] +fn check_thin_dyn(make: impl FnOnce() -> T) { + let value = make(); + let wanted_debug = format!("{value:?}"); + let boxed: ThinBox = ThinBox::new_unsize(value.clone()); + let val = &*boxed; + // wide reference -> wide pointer -> thin pointer + verify_aligned(val as *const dyn Debug as *const T); + let got_debug = format!("{val:?}"); + assert_eq!(wanted_debug, got_debug); +} + +macro_rules! define_test { + ( + @test_name: $testname:ident; + + $(#[$m:meta])* + struct $Type:ident($inner:ty); + + $($test_stmts:tt)* + ) => { + #[test] + fn $testname() { + use core::sync::atomic::{AtomicIsize, Ordering}; + // Define the type, and implement new/clone/drop in such a way that + // the number of live instances will be counted. + $(#[$m])* + #[derive(Debug, PartialEq)] + struct $Type { + _priv: $inner, + } + + impl Clone for $Type { + fn clone(&self) -> Self { + verify_aligned(self); + Self::new(self._priv.clone()) + } + } + + impl Drop for $Type { + fn drop(&mut self) { + verify_aligned(self); + Self::modify_live(-1); + } + } + + impl $Type { + fn new(i: $inner) -> Self { + Self::modify_live(1); + Self { _priv: i } + } + + fn modify_live(n: isize) -> isize { + static COUNTER: AtomicIsize = AtomicIsize::new(0); + COUNTER.fetch_add(n, Ordering::Relaxed) + n + } + + fn live_objects() -> isize { + Self::modify_live(0) + } + } + // Run the test statements + let _: () = { $($test_stmts)* }; + // Check that we didn't leak anything, or call drop too many times. + assert_eq!( + $Type::live_objects(), 0, + "Wrong number of drops of {}, `initializations - drops` should be 0.", + stringify!($Type), + ); + } + }; +} + +define_test! { + @test_name: align1zst; + struct Align1Zst(()); + + check_thin_sized(|| Align1Zst::new(())); + check_thin_dyn(|| Align1Zst::new(())); +} + +define_test! { + @test_name: align1small; + struct Align1Small(u8); + + check_thin_sized(|| Align1Small::new(50)); + check_thin_dyn(|| Align1Small::new(50)); +} + +define_test! { + @test_name: align1_size_not_pow2; + struct Align64NotPow2Size([u8; 79]); + + check_thin_sized(|| Align64NotPow2Size::new([100; 79])); + check_thin_dyn(|| Align64NotPow2Size::new([100; 79])); +} + +define_test! { + @test_name: align1big; + struct Align1Big([u8; 256]); + + check_thin_sized(|| Align1Big::new([5u8; 256])); + check_thin_dyn(|| Align1Big::new([5u8; 256])); +} + +// Note: `#[repr(align(2))]` is worth testing because +// - can have pointers which are misaligned, unlike align(1) +// - is still expected to have an alignment less than the alignment of a vtable. +define_test! { + @test_name: align2zst; + #[repr(align(2))] + struct Align2Zst(()); + + check_thin_sized(|| Align2Zst::new(())); + check_thin_dyn(|| Align2Zst::new(())); +} + +define_test! { + @test_name: align2small; + #[repr(align(2))] + struct Align2Small(u8); + + check_thin_sized(|| Align2Small::new(60)); + check_thin_dyn(|| Align2Small::new(60)); +} + +define_test! { + @test_name: align2full; + #[repr(align(2))] + struct Align2Full([u8; 2]); + check_thin_sized(|| Align2Full::new([3u8; 2])); + check_thin_dyn(|| Align2Full::new([3u8; 2])); +} + +define_test! { + @test_name: align2_size_not_pow2; + #[repr(align(2))] + struct Align2NotPower2Size([u8; 6]); + + check_thin_sized(|| Align2NotPower2Size::new([3; 6])); + check_thin_dyn(|| Align2NotPower2Size::new([3; 6])); +} + +define_test! { + @test_name: align2big; + #[repr(align(2))] + struct Align2Big([u8; 256]); + + check_thin_sized(|| Align2Big::new([5u8; 256])); + check_thin_dyn(|| Align2Big::new([5u8; 256])); +} + +define_test! { + @test_name: align64zst; + #[repr(align(64))] + struct Align64Zst(()); + + check_thin_sized(|| Align64Zst::new(())); + check_thin_dyn(|| Align64Zst::new(())); +} + +define_test! { + @test_name: align64small; + #[repr(align(64))] + struct Align64Small(u8); + + check_thin_sized(|| Align64Small::new(50)); + check_thin_dyn(|| Align64Small::new(50)); +} + +define_test! { + @test_name: align64med; + #[repr(align(64))] + struct Align64Med([u8; 64]); + check_thin_sized(|| Align64Med::new([10; 64])); + check_thin_dyn(|| Align64Med::new([10; 64])); +} + +define_test! { + @test_name: align64_size_not_pow2; + #[repr(align(64))] + struct Align64NotPow2Size([u8; 192]); + + check_thin_sized(|| Align64NotPow2Size::new([10; 192])); + check_thin_dyn(|| Align64NotPow2Size::new([10; 192])); +} + +define_test! { + @test_name: align64big; + #[repr(align(64))] + struct Align64Big([u8; 256]); + + check_thin_sized(|| Align64Big::new([10; 256])); + check_thin_dyn(|| Align64Big::new([10; 256])); +} -- cgit v1.2.3