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Auto merge of #127486 - matthiaskrgr:rollup-lvv018b, r=matthiaskrgr
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Rollup of 5 pull requests

Successful merges:

 - #120248 (Make casts of pointers to trait objects stricter)
 - #127355 (Mark format! with must_use hint)
 - #127399 (Verify that allocations output by GVN are sufficiently aligned.)
 - #127460 (clarify `sys::unix::fd::FileDesc::drop` comment)
 - #127467 (bootstrap: once_cell::sync::Lazy -> std::sync::LazyLock)

Failed merges:

 - #127357 (Remove `StructuredDiag`)

r? `@ghost`
`@rustbot` modify labels: rollup
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@bors
bors committed Jul 8, 2024
2 parents cfd7cf5 + a659f7a commit a06e9c8
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Showing 59 changed files with 900 additions and 259 deletions.
67 changes: 66 additions & 1 deletion compiler/rustc_borrowck/src/type_check/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -38,6 +38,7 @@ use rustc_span::def_id::CRATE_DEF_ID;
use rustc_span::source_map::Spanned;
use rustc_span::symbol::sym;
use rustc_span::Span;
use rustc_span::DUMMY_SP;
use rustc_target::abi::{FieldIdx, FIRST_VARIANT};
use rustc_trait_selection::traits::query::type_op::custom::scrape_region_constraints;
use rustc_trait_selection::traits::query::type_op::custom::CustomTypeOp;
Expand All @@ -49,6 +50,7 @@ use rustc_mir_dataflow::impls::MaybeInitializedPlaces;
use rustc_mir_dataflow::move_paths::MoveData;
use rustc_mir_dataflow::ResultsCursor;

use crate::renumber::RegionCtxt;
use crate::session_diagnostics::{MoveUnsized, SimdIntrinsicArgConst};
use crate::{
borrow_set::BorrowSet,
Expand Down Expand Up @@ -2333,7 +2335,57 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
let cast_ty_from = CastTy::from_ty(ty_from);
let cast_ty_to = CastTy::from_ty(*ty);
match (cast_ty_from, cast_ty_to) {
(Some(CastTy::Ptr(_)), Some(CastTy::Ptr(_))) => (),
(Some(CastTy::Ptr(src)), Some(CastTy::Ptr(dst))) => {
let mut normalize = |t| self.normalize(t, location);
let src_tail =
tcx.struct_tail_with_normalize(src.ty, &mut normalize, || ());
let dst_tail =
tcx.struct_tail_with_normalize(dst.ty, &mut normalize, || ());

// This checks (lifetime part of) vtable validity for pointer casts,
// which is irrelevant when there are aren't principal traits on both sides (aka only auto traits).
//
// Note that other checks (such as denying `dyn Send` -> `dyn Debug`) are in `rustc_hir_typeck`.
if let ty::Dynamic(src_tty, ..) = src_tail.kind()
&& let ty::Dynamic(dst_tty, ..) = dst_tail.kind()
&& src_tty.principal().is_some()
&& dst_tty.principal().is_some()
{
// Remove auto traits.
// Auto trait checks are handled in `rustc_hir_typeck` as FCW.
let src_obj = tcx.mk_ty_from_kind(ty::Dynamic(
tcx.mk_poly_existential_predicates(
&src_tty.without_auto_traits().collect::<Vec<_>>(),
),
tcx.lifetimes.re_static,
ty::Dyn,
));
let dst_obj = tcx.mk_ty_from_kind(ty::Dynamic(
tcx.mk_poly_existential_predicates(
&dst_tty.without_auto_traits().collect::<Vec<_>>(),
),
tcx.lifetimes.re_static,
ty::Dyn,
));

// Replace trait object lifetimes with fresh vars, to allow casts like
// `*mut dyn FnOnce() + 'a` -> `*mut dyn FnOnce() + 'static`,
let src_obj =
freshen_single_trait_object_lifetime(self.infcx, src_obj);
let dst_obj =
freshen_single_trait_object_lifetime(self.infcx, dst_obj);

debug!(?src_tty, ?dst_tty, ?src_obj, ?dst_obj);

self.eq_types(
src_obj,
dst_obj,
location.to_locations(),
ConstraintCategory::Cast { unsize_to: None },
)
.unwrap();
}
}
_ => {
span_mirbug!(
self,
Expand Down Expand Up @@ -2856,3 +2908,16 @@ impl<'tcx> TypeOp<'tcx> for InstantiateOpaqueType<'tcx> {
Ok(output)
}
}

fn freshen_single_trait_object_lifetime<'tcx>(
infcx: &BorrowckInferCtxt<'tcx>,
ty: Ty<'tcx>,
) -> Ty<'tcx> {
let &ty::Dynamic(tty, _, dyn_kind @ ty::Dyn) = ty.kind() else { bug!("expected trait object") };

let fresh = infcx
.next_region_var(rustc_infer::infer::RegionVariableOrigin::MiscVariable(DUMMY_SP), || {
RegionCtxt::Unknown
});
infcx.tcx.mk_ty_from_kind(ty::Dynamic(tty, fresh, dyn_kind))
}
14 changes: 10 additions & 4 deletions compiler/rustc_errors/src/diagnostic_impls.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -298,15 +298,21 @@ impl IntoDiagArg for hir::def::Namespace {
}

#[derive(Clone)]
pub struct DiagSymbolList(Vec<Symbol>);
pub struct DiagSymbolList<S = Symbol>(Vec<S>);

impl From<Vec<Symbol>> for DiagSymbolList {
fn from(v: Vec<Symbol>) -> Self {
impl<S> From<Vec<S>> for DiagSymbolList<S> {
fn from(v: Vec<S>) -> Self {
DiagSymbolList(v)
}
}

impl IntoDiagArg for DiagSymbolList {
impl<S> FromIterator<S> for DiagSymbolList<S> {
fn from_iter<T: IntoIterator<Item = S>>(iter: T) -> Self {
iter.into_iter().collect::<Vec<_>>().into()
}
}

impl<S: std::fmt::Display> IntoDiagArg for DiagSymbolList<S> {
fn into_diag_arg(self) -> DiagArgValue {
DiagArgValue::StrListSepByAnd(
self.0.into_iter().map(|sym| Cow::Owned(format!("`{sym}`"))).collect(),
Expand Down
5 changes: 5 additions & 0 deletions compiler/rustc_hir_typeck/messages.ftl
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Original file line number Diff line number Diff line change
Expand Up @@ -138,6 +138,11 @@ hir_typeck_option_result_asref = use `{$def_path}::as_ref` to convert `{$expecte
hir_typeck_option_result_cloned = use `{$def_path}::cloned` to clone the value inside the `{$def_path}`
hir_typeck_option_result_copied = use `{$def_path}::copied` to copy the value inside the `{$def_path}`
hir_typeck_ptr_cast_add_auto_to_object = adding {$traits_len ->
[1] an auto trait {$traits}
*[other] auto traits {$traits}
} to a trait object in a pointer cast may cause UB later on
hir_typeck_remove_semi_for_coerce = you might have meant to return the `match` expression
hir_typeck_remove_semi_for_coerce_expr = this could be implicitly returned but it is a statement, not a tail expression
hir_typeck_remove_semi_for_coerce_ret = the `match` arms can conform to this return type
Expand Down
148 changes: 117 additions & 31 deletions compiler/rustc_hir_typeck/src/cast.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -32,9 +32,9 @@ use super::FnCtxt;

use crate::errors;
use crate::type_error_struct;
use hir::ExprKind;
use rustc_data_structures::fx::FxHashSet;
use rustc_errors::{codes::*, Applicability, Diag, ErrorGuaranteed};
use rustc_hir as hir;
use rustc_hir::{self as hir, ExprKind};
use rustc_macros::{TypeFoldable, TypeVisitable};
use rustc_middle::bug;
use rustc_middle::mir::Mutability;
Expand All @@ -44,7 +44,7 @@ use rustc_middle::ty::error::TypeError;
use rustc_middle::ty::TyCtxt;
use rustc_middle::ty::{self, Ty, TypeAndMut, TypeVisitableExt, VariantDef};
use rustc_session::lint;
use rustc_span::def_id::{DefId, LOCAL_CRATE};
use rustc_span::def_id::LOCAL_CRATE;
use rustc_span::symbol::sym;
use rustc_span::Span;
use rustc_span::DUMMY_SP;
Expand Down Expand Up @@ -73,7 +73,7 @@ enum PointerKind<'tcx> {
/// No metadata attached, ie pointer to sized type or foreign type
Thin,
/// A trait object
VTable(Option<DefId>),
VTable(&'tcx ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>>),
/// Slice
Length,
/// The unsize info of this projection or opaque type
Expand Down Expand Up @@ -101,7 +101,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {

Ok(match *t.kind() {
ty::Slice(_) | ty::Str => Some(PointerKind::Length),
ty::Dynamic(tty, _, ty::Dyn) => Some(PointerKind::VTable(tty.principal_def_id())),
ty::Dynamic(tty, _, ty::Dyn) => Some(PointerKind::VTable(tty)),
ty::Adt(def, args) if def.is_struct() => match def.non_enum_variant().tail_opt() {
None => Some(PointerKind::Thin),
Some(f) => {
Expand Down Expand Up @@ -755,7 +755,7 @@ impl<'a, 'tcx> CastCheck<'tcx> {
Err(CastError::IllegalCast)
}

// ptr -> *
// ptr -> ptr
(Ptr(m_e), Ptr(m_c)) => self.check_ptr_ptr_cast(fcx, m_e, m_c), // ptr-ptr-cast

// ptr-addr-cast
Expand Down Expand Up @@ -799,40 +799,126 @@ impl<'a, 'tcx> CastCheck<'tcx> {
fn check_ptr_ptr_cast(
&self,
fcx: &FnCtxt<'a, 'tcx>,
m_expr: ty::TypeAndMut<'tcx>,
m_cast: ty::TypeAndMut<'tcx>,
m_src: ty::TypeAndMut<'tcx>,
m_dst: ty::TypeAndMut<'tcx>,
) -> Result<CastKind, CastError> {
debug!("check_ptr_ptr_cast m_expr={:?} m_cast={:?}", m_expr, m_cast);
debug!("check_ptr_ptr_cast m_src={m_src:?} m_dst={m_dst:?}");
// ptr-ptr cast. vtables must match.

let expr_kind = fcx.pointer_kind(m_expr.ty, self.span)?;
let cast_kind = fcx.pointer_kind(m_cast.ty, self.span)?;
let src_kind = fcx.tcx.erase_regions(fcx.pointer_kind(m_src.ty, self.span)?);
let dst_kind = fcx.tcx.erase_regions(fcx.pointer_kind(m_dst.ty, self.span)?);

let Some(cast_kind) = cast_kind else {
match (src_kind, dst_kind) {
// We can't cast if target pointer kind is unknown
return Err(CastError::UnknownCastPtrKind);
};
(_, None) => Err(CastError::UnknownCastPtrKind),
// Cast to thin pointer is OK
(_, Some(PointerKind::Thin)) => Ok(CastKind::PtrPtrCast),

// Cast to thin pointer is OK
if cast_kind == PointerKind::Thin {
return Ok(CastKind::PtrPtrCast);
}

let Some(expr_kind) = expr_kind else {
// We can't cast to fat pointer if source pointer kind is unknown
return Err(CastError::UnknownExprPtrKind);
};
(None, _) => Err(CastError::UnknownExprPtrKind),

// thin -> fat? report invalid cast (don't complain about vtable kinds)
(Some(PointerKind::Thin), _) => Err(CastError::SizedUnsizedCast),

// trait object -> trait object? need to do additional checks
(Some(PointerKind::VTable(src_tty)), Some(PointerKind::VTable(dst_tty))) => {
match (src_tty.principal(), dst_tty.principal()) {
// A<dyn Src<...> + SrcAuto> -> B<dyn Dst<...> + DstAuto>. need to make sure
// - `Src` and `Dst` traits are the same
// - traits have the same generic arguments
// - `SrcAuto` is a superset of `DstAuto`
(Some(src_principal), Some(dst_principal)) => {
let tcx = fcx.tcx;

// Check that the traits are actually the same.
// The `dyn Src = dyn Dst` check below would suffice,
// but this may produce a better diagnostic.
//
// Note that trait upcasting goes through a different mechanism (`coerce_unsized`)
// and is unaffected by this check.
if src_principal.def_id() != dst_principal.def_id() {
return Err(CastError::DifferingKinds);
}

// thin -> fat? report invalid cast (don't complain about vtable kinds)
if expr_kind == PointerKind::Thin {
return Err(CastError::SizedUnsizedCast);
}
// We need to reconstruct trait object types.
// `m_src` and `m_dst` won't work for us here because they will potentially
// contain wrappers, which we do not care about.
//
// e.g. we want to allow `dyn T -> (dyn T,)`, etc.
//
// We also need to skip auto traits to emit an FCW and not an error.
let src_obj = tcx.mk_ty_from_kind(ty::Dynamic(
tcx.mk_poly_existential_predicates(
&src_tty.without_auto_traits().collect::<Vec<_>>(),
),
tcx.lifetimes.re_erased,
ty::Dyn,
));
let dst_obj = tcx.mk_ty_from_kind(ty::Dynamic(
tcx.mk_poly_existential_predicates(
&dst_tty.without_auto_traits().collect::<Vec<_>>(),
),
tcx.lifetimes.re_erased,
ty::Dyn,
));

// vtable kinds must match
if fcx.tcx.erase_regions(cast_kind) == fcx.tcx.erase_regions(expr_kind) {
Ok(CastKind::PtrPtrCast)
} else {
Err(CastError::DifferingKinds)
// `dyn Src = dyn Dst`, this checks for matching traits/generics
fcx.demand_eqtype(self.span, src_obj, dst_obj);

// Check that `SrcAuto` (+auto traits implied by `Src`) is a superset of `DstAuto`.
// Emit an FCW otherwise.
let src_auto: FxHashSet<_> = src_tty
.auto_traits()
.chain(
tcx.supertrait_def_ids(src_principal.def_id())
.filter(|def_id| tcx.trait_is_auto(*def_id)),
)
.collect();

let added = dst_tty
.auto_traits()
.filter(|trait_did| !src_auto.contains(trait_did))
.collect::<Vec<_>>();

if !added.is_empty() {
tcx.emit_node_span_lint(
lint::builtin::PTR_CAST_ADD_AUTO_TO_OBJECT,
self.expr.hir_id,
self.span,
errors::PtrCastAddAutoToObject {
traits_len: added.len(),
traits: {
let mut traits: Vec<_> = added
.into_iter()
.map(|trait_did| tcx.def_path_str(trait_did))
.collect();

traits.sort();
traits.into()
},
},
)
}

Ok(CastKind::PtrPtrCast)
}

// dyn Auto -> dyn Auto'? ok.
(None, None) => Ok(CastKind::PtrPtrCast),

// dyn Trait -> dyn Auto? should be ok, but we used to not allow it.
// FIXME: allow this
(Some(_), None) => Err(CastError::DifferingKinds),

// dyn Auto -> dyn Trait? not ok.
(None, Some(_)) => Err(CastError::DifferingKinds),
}
}

// fat -> fat? metadata kinds must match
(Some(src_kind), Some(dst_kind)) if src_kind == dst_kind => Ok(CastKind::PtrPtrCast),

(_, _) => Err(CastError::DifferingKinds),
}
}

Expand Down
11 changes: 9 additions & 2 deletions compiler/rustc_hir_typeck/src/errors.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4,8 +4,8 @@ use std::borrow::Cow;

use crate::fluent_generated as fluent;
use rustc_errors::{
codes::*, Applicability, Diag, DiagArgValue, EmissionGuarantee, IntoDiagArg, MultiSpan,
SubdiagMessageOp, Subdiagnostic,
codes::*, Applicability, Diag, DiagArgValue, DiagSymbolList, EmissionGuarantee, IntoDiagArg,
MultiSpan, SubdiagMessageOp, Subdiagnostic,
};
use rustc_macros::{Diagnostic, LintDiagnostic, Subdiagnostic};
use rustc_middle::ty::{self, Ty};
Expand Down Expand Up @@ -253,6 +253,13 @@ pub struct LossyProvenanceInt2Ptr<'tcx> {
pub sugg: LossyProvenanceInt2PtrSuggestion,
}

#[derive(LintDiagnostic)]
#[diag(hir_typeck_ptr_cast_add_auto_to_object)]
pub struct PtrCastAddAutoToObject {
pub traits_len: usize,
pub traits: DiagSymbolList<String>,
}

#[derive(Subdiagnostic)]
#[multipart_suggestion(hir_typeck_suggestion, applicability = "has-placeholders")]
pub struct LossyProvenanceInt2PtrSuggestion {
Expand Down
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