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Auto merge of rust-lang#130907 - GuillaumeGomez:rollup-423r4i4, r=Gui…
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…llaumeGomez

Rollup of 11 pull requests

Successful merges:

 - rust-lang#130279 (Document subtleties of `ManuallyDrop`)
 - rust-lang#130517 (Add the library workspace to the suggested rust-analyzer config)
 - rust-lang#130820 (Fix diagnostics for coroutines with () as input.)
 - rust-lang#130833 (Fix the misleading diagnostic for `let_underscore_drop` on type without `Drop` implementation)
 - rust-lang#130845 (Utf8Chunks: add link to Utf8Chunk)
 - rust-lang#130850 (Pass Module Analysis Manager to Standard Instrumentations)
 - rust-lang#130861 (Use `mem::offset_of!` for `sockaddr_un.sun_path`)
 - rust-lang#130862 (rustdoc: do not animate :target when user prefers reduced motion)
 - rust-lang#130868 (Update FIXME comment in s390x_unknown_linux_*.rs)
 - rust-lang#130879 (Pass correct HirId to late_bound_vars in diagnostic code)
 - rust-lang#130880 (add missing FIXME(const-hack))

r? `@ghost`
`@rustbot` modify labels: rollup
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bors committed Sep 26, 2024
2 parents 2bd1e89 + 3d4d45f commit 58420a0
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Showing 27 changed files with 282 additions and 100 deletions.
3 changes: 2 additions & 1 deletion compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs
Original file line number Diff line number Diff line change
Expand Up @@ -882,7 +882,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
let ty = self.lowerer().lower_ty(hir_ty);
debug!(?ty, "return type (lowered)");
debug!(?expected, "expected type");
let bound_vars = self.tcx.late_bound_vars(hir_ty.hir_id.owner.into());
let bound_vars =
self.tcx.late_bound_vars(self.tcx.local_def_id_to_hir_id(fn_id));
let ty = Binder::bind_with_vars(ty, bound_vars);
let ty = self.normalize(hir_ty.span, ty);
let ty = self.tcx.instantiate_bound_regions_with_erased(ty);
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2 changes: 1 addition & 1 deletion compiler/rustc_lint/messages.ftl
Original file line number Diff line number Diff line change
Expand Up @@ -531,7 +531,7 @@ lint_non_binding_let_multi_suggestion =
consider immediately dropping the value
lint_non_binding_let_on_drop_type =
non-binding let on a type that implements `Drop`
non-binding let on a type that has a destructor
lint_non_binding_let_on_sync_lock = non-binding let on a synchronization lock
.label = this lock is not assigned to a binding and is immediately dropped
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2 changes: 1 addition & 1 deletion compiler/rustc_lint/src/let_underscore.rs
Original file line number Diff line number Diff line change
Expand Up @@ -51,7 +51,7 @@ declare_lint! {
/// intent.
pub LET_UNDERSCORE_DROP,
Allow,
"non-binding let on a type that implements `Drop`"
"non-binding let on a type that has a destructor"
}

declare_lint! {
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11 changes: 6 additions & 5 deletions compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -732,12 +732,7 @@ extern "C" LLVMRustResult LLVMRustOptimize(
PTO.SLPVectorization = SLPVectorize;
PTO.MergeFunctions = MergeFunctions;

// FIXME: We may want to expose this as an option.
bool DebugPassManager = false;

PassInstrumentationCallbacks PIC;
StandardInstrumentations SI(TheModule->getContext(), DebugPassManager);
SI.registerCallbacks(PIC);

if (LlvmSelfProfiler) {
LLVMSelfProfileInitializeCallbacks(PIC, LlvmSelfProfiler,
Expand Down Expand Up @@ -784,6 +779,12 @@ extern "C" LLVMRustResult LLVMRustOptimize(
CGSCCAnalysisManager CGAM;
ModuleAnalysisManager MAM;

// FIXME: We may want to expose this as an option.
bool DebugPassManager = false;

StandardInstrumentations SI(TheModule->getContext(), DebugPassManager);
SI.registerCallbacks(PIC, &MAM);

if (LLVMPluginsLen) {
auto PluginsStr = StringRef(LLVMPlugins, LLVMPluginsLen);
SmallVector<StringRef> Plugins;
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Original file line number Diff line number Diff line change
Expand Up @@ -6,9 +6,8 @@ pub(crate) fn target() -> Target {
base.endian = Endian::Big;
// z10 is the oldest CPU supported by LLVM
base.cpu = "z10".into();
// FIXME: The ABI implementation in cabi_s390x.rs is for now hard-coded to assume the no-vector
// ABI. Pass the -vector feature string to LLVM to respect this assumption. On LLVM < 16, we
// also strip v128 from the data_layout below to match the older LLVM's expectation.
// FIXME: The ABI implementation in abi/call/s390x.rs is for now hard-coded to assume the no-vector
// ABI. Pass the -vector feature string to LLVM to respect this assumption.
base.features = "-vector".into();
base.max_atomic_width = Some(128);
base.min_global_align = Some(16);
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Original file line number Diff line number Diff line change
Expand Up @@ -6,9 +6,8 @@ pub(crate) fn target() -> Target {
base.endian = Endian::Big;
// z10 is the oldest CPU supported by LLVM
base.cpu = "z10".into();
// FIXME: The ABI implementation in cabi_s390x.rs is for now hard-coded to assume the no-vector
// ABI. Pass the -vector feature string to LLVM to respect this assumption. On LLVM < 16, we
// also strip v128 from the data_layout below to match the older LLVM's expectation.
// FIXME: The ABI implementation in abi/call/s390x.rs is for now hard-coded to assume the no-vector
// ABI. Pass the -vector feature string to LLVM to respect this assumption.
base.features = "-vector".into();
base.max_atomic_width = Some(128);
base.min_global_align = Some(16);
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Original file line number Diff line number Diff line change
Expand Up @@ -2635,49 +2635,47 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
// This shouldn't be common unless manually implementing one of the
// traits manually, but don't make it more confusing when it does
// happen.
Ok(
if Some(expected_trait_ref.def_id) != self.tcx.lang_items().coroutine_trait()
&& not_tupled
{
self.report_and_explain_type_error(
TypeTrace::trait_refs(
&obligation.cause,
true,
expected_trait_ref,
found_trait_ref,
),
ty::error::TypeError::Mismatch,
)
} else if found.len() == expected.len() {
self.report_closure_arg_mismatch(
span,
found_span,
found_trait_ref,
expected_trait_ref,
obligation.cause.code(),
found_node,
obligation.param_env,
)
} else {
let (closure_span, closure_arg_span, found) = found_did
.and_then(|did| {
let node = self.tcx.hir().get_if_local(did)?;
let (found_span, closure_arg_span, found) =
self.get_fn_like_arguments(node)?;
Some((Some(found_span), closure_arg_span, found))
})
.unwrap_or((found_span, None, found));

self.report_arg_count_mismatch(
if Some(expected_trait_ref.def_id) != self.tcx.lang_items().coroutine_trait() && not_tupled
{
return Ok(self.report_and_explain_type_error(
TypeTrace::trait_refs(&obligation.cause, true, expected_trait_ref, found_trait_ref),
ty::error::TypeError::Mismatch,
));
}
if found.len() != expected.len() {
let (closure_span, closure_arg_span, found) = found_did
.and_then(|did| {
let node = self.tcx.hir().get_if_local(did)?;
let (found_span, closure_arg_span, found) = self.get_fn_like_arguments(node)?;
Some((Some(found_span), closure_arg_span, found))
})
.unwrap_or((found_span, None, found));

// If the coroutine take a single () as its argument,
// the trait argument would found the coroutine take 0 arguments,
// but get_fn_like_arguments would give 1 argument.
// This would result in "Expected to take 1 argument, but it takes 1 argument".
// Check again to avoid this.
if found.len() != expected.len() {
return Ok(self.report_arg_count_mismatch(
span,
closure_span,
expected,
found,
found_trait_ty.is_closure(),
closure_arg_span,
)
},
)
));
}
}
Ok(self.report_closure_arg_mismatch(
span,
found_span,
found_trait_ref,
expected_trait_ref,
obligation.cause.code(),
found_node,
obligation.param_env,
))
}

/// Given some node representing a fn-like thing in the HIR map,
Expand Down
130 changes: 118 additions & 12 deletions library/core/src/mem/manually_drop.rs
Original file line number Diff line number Diff line change
@@ -1,22 +1,21 @@
use crate::ops::{Deref, DerefMut, DerefPure};
use crate::ptr;

/// A wrapper to inhibit the compiler from automatically calling `T`’s destructor.
/// This wrapper is 0-cost.
/// A wrapper to inhibit the compiler from automatically calling `T`’s
/// destructor. This wrapper is 0-cost.
///
/// `ManuallyDrop<T>` is guaranteed to have the same layout and bit validity as
/// `T`, and is subject to the same layout optimizations as `T`. As a consequence,
/// it has *no effect* on the assumptions that the compiler makes about its
/// contents. For example, initializing a `ManuallyDrop<&mut T>` with [`mem::zeroed`]
/// is undefined behavior. If you need to handle uninitialized data, use
/// [`MaybeUninit<T>`] instead.
/// `T`, and is subject to the same layout optimizations as `T`. As a
/// consequence, it has *no effect* on the assumptions that the compiler makes
/// about its contents. For example, initializing a `ManuallyDrop<&mut T>` with
/// [`mem::zeroed`] is undefined behavior. If you need to handle uninitialized
/// data, use [`MaybeUninit<T>`] instead.
///
/// Note that accessing the value inside a `ManuallyDrop<T>` is safe.
/// This means that a `ManuallyDrop<T>` whose content has been dropped must not
/// be exposed through a public safe API.
/// Correspondingly, `ManuallyDrop::drop` is unsafe.
/// Note that accessing the value inside a `ManuallyDrop<T>` is safe. This means
/// that a `ManuallyDrop<T>` whose content has been dropped must not be exposed
/// through a public safe API. Correspondingly, `ManuallyDrop::drop` is unsafe.
///
/// # `ManuallyDrop` and drop order.
/// # `ManuallyDrop` and drop order
///
/// Rust has a well-defined [drop order] of values. To make sure that fields or
/// locals are dropped in a specific order, reorder the declarations such that
Expand All @@ -40,9 +39,116 @@ use crate::ptr;
/// }
/// ```
///
/// # Interaction with `Box`
///
/// Currently, if you have a `ManuallyDrop<T>`, where the type `T` is a `Box` or
/// contains a `Box` inside, then dropping the `T` followed by moving the
/// `ManuallyDrop<T>` is [considered to be undefined
/// behavior](https://github.com/rust-lang/unsafe-code-guidelines/issues/245).
/// That is, the following code causes undefined behavior:
///
/// ```no_run
/// use std::mem::ManuallyDrop;
///
/// let mut x = ManuallyDrop::new(Box::new(42));
/// unsafe {
/// ManuallyDrop::drop(&mut x);
/// }
/// let y = x; // Undefined behavior!
/// ```
///
/// This is [likely to change in the
/// future](https://rust-lang.github.io/rfcs/3336-maybe-dangling.html). In the
/// meantime, consider using [`MaybeUninit`] instead.
///
/// # Safety hazards when storing `ManuallyDrop` in a struct or an enum.
///
/// Special care is needed when all of the conditions below are met:
/// * A struct or enum contains a `ManuallyDrop`.
/// * The `ManuallyDrop` is not inside a `union`.
/// * The struct or enum is part of public API, or is stored in a struct or an
/// enum that is part of public API.
/// * There is code that drops the contents of the `ManuallyDrop` field, and
/// this code is outside the struct or enum's `Drop` implementation.
///
/// In particular, the following hazards may occur:
///
/// #### Storing generic types
///
/// If the `ManuallyDrop` contains a client-supplied generic type, the client
/// might provide a `Box` as that type. This would cause undefined behavior when
/// the struct or enum is later moved, as mentioned in the previous section. For
/// example, the following code causes undefined behavior:
///
/// ```no_run
/// use std::mem::ManuallyDrop;
///
/// pub struct BadOption<T> {
/// // Invariant: Has been dropped iff `is_some` is false.
/// value: ManuallyDrop<T>,
/// is_some: bool,
/// }
/// impl<T> BadOption<T> {
/// pub fn new(value: T) -> Self {
/// Self { value: ManuallyDrop::new(value), is_some: true }
/// }
/// pub fn change_to_none(&mut self) {
/// if self.is_some {
/// self.is_some = false;
/// unsafe {
/// // SAFETY: `value` hasn't been dropped yet, as per the invariant
/// // (This is actually unsound!)
/// ManuallyDrop::drop(&mut self.value);
/// }
/// }
/// }
/// }
///
/// // In another crate:
///
/// let mut option = BadOption::new(Box::new(42));
/// option.change_to_none();
/// let option2 = option; // Undefined behavior!
/// ```
///
/// #### Deriving traits
///
/// Deriving `Debug`, `Clone`, `PartialEq`, `PartialOrd`, `Ord`, or `Hash` on
/// the struct or enum could be unsound, since the derived implementations of
/// these traits would access the `ManuallyDrop` field. For example, the
/// following code causes undefined behavior:
///
/// ```no_run
/// use std::mem::ManuallyDrop;
///
/// // This derive is unsound in combination with the `ManuallyDrop::drop` call.
/// #[derive(Debug)]
/// pub struct Foo {
/// value: ManuallyDrop<String>,
/// }
/// impl Foo {
/// pub fn new() -> Self {
/// let mut temp = Self {
/// value: ManuallyDrop::new(String::from("Unsafe rust is hard."))
/// };
/// unsafe {
/// // SAFETY: `value` hasn't been dropped yet.
/// ManuallyDrop::drop(&mut temp.value);
/// }
/// temp
/// }
/// }
///
/// // In another crate:
///
/// let foo = Foo::new();
/// println!("{:?}", foo); // Undefined behavior!
/// ```
///
/// [drop order]: https://doc.rust-lang.org/reference/destructors.html
/// [`mem::zeroed`]: crate::mem::zeroed
/// [`MaybeUninit<T>`]: crate::mem::MaybeUninit
/// [`MaybeUninit`]: crate::mem::MaybeUninit
#[stable(feature = "manually_drop", since = "1.20.0")]
#[lang = "manually_drop"]
#[derive(Copy, Clone, Debug, Default, PartialEq, Eq, PartialOrd, Ord, Hash)]
Expand Down
2 changes: 1 addition & 1 deletion library/core/src/ptr/alignment.rs
Original file line number Diff line number Diff line change
Expand Up @@ -155,7 +155,7 @@ impl Alignment {
!(unsafe { self.as_usize().unchecked_sub(1) })
}

// Remove me once `Ord::max` is usable in const
// FIXME(const-hack) Remove me once `Ord::max` is usable in const
pub(crate) const fn max(a: Self, b: Self) -> Self {
if a.as_usize() > b.as_usize() { a } else { b }
}
Expand Down
4 changes: 4 additions & 0 deletions library/core/src/str/lossy.rs
Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,8 @@ impl [u8] {
/// Creates an iterator over the contiguous valid UTF-8 ranges of this
/// slice, and the non-UTF-8 fragments in between.
///
/// See the [`Utf8Chunk`] type for documenation of the items yielded by this iterator.
///
/// # Examples
///
/// This function formats arbitrary but mostly-UTF-8 bytes into Rust source
Expand Down Expand Up @@ -148,6 +150,8 @@ impl fmt::Debug for Debug<'_> {
/// If you want a simple conversion from UTF-8 byte slices to string slices,
/// [`from_utf8`] is easier to use.
///
/// See the [`Utf8Chunk`] type for documenation of the items yielded by this iterator.
///
/// [byteslice]: slice
/// [`from_utf8`]: super::from_utf8
///
Expand Down
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