bjoernager/rust
bjoernager/rust
1
Fork 0
Code Issues Pull requests Activity

Auto merge of #130390 - matthiaskrgr:rollup-evbfwe2, r=matthiaskrgr

Browse source 
Rollup of 5 pull requests

Successful merges:

 - #129195 (Stabilize `&mut` (and `*mut`) as well as `&Cell` (and `*const Cell`) in const)
 - #130118 (move Option::unwrap_unchecked into const_option feature gate)
 - #130295 (Fix target-cpu fpu features on Armv8-R.)
 - #130371 (Correctly account for niche-optimized tags in rustc_transmute)
 - #130381 (library: Compute Rust exception class from its string repr)

r? `@ghost`
`@rustbot` modify labels: rollup
This commit is contained in:
bors 2024-09-15 11:19:28 +00:00
commit dde7d6649e
181 changed files with 426 additions and 1738 deletions
Download patch file Download diff file Expand all files Collapse all files

254
compiler/rustc_const_eval/src/check_consts/check.rs
View file

@ -11,18 +11,17 @@ use rustc_hir::{self as hir, LangItem};
use rustc_index::bit_set::BitSet;
use rustc_infer::infer::TyCtxtInferExt;
use rustc_infer::traits::ObligationCause;
use rustc_middle::mir::visit::{MutatingUseContext, NonMutatingUseContext, PlaceContext, Visitor};
use rustc_middle::mir::visit::Visitor;
use rustc_middle::mir::*;
use rustc_middle::span_bug;
use rustc_middle::ty::adjustment::PointerCoercion;
use rustc_middle::ty::{self, Instance, InstanceKind, Ty, TyCtxt, TypeVisitableExt};
use rustc_middle::ty::{self, Instance, InstanceKind, Ty, TypeVisitableExt};
use rustc_mir_dataflow::impls::MaybeStorageLive;
use rustc_mir_dataflow::storage::always_storage_live_locals;
use rustc_mir_dataflow::Analysis;
use rustc_span::{sym, Span, Symbol, DUMMY_SP};
use rustc_trait_selection::error_reporting::InferCtxtErrorExt;
use rustc_trait_selection::traits::{self, ObligationCauseCode, ObligationCtxt};
use rustc_type_ir::visit::{TypeSuperVisitable, TypeVisitor};
use tracing::{debug, instrument, trace};
use super::ops::{self, NonConstOp, Status};
@ -166,24 +165,6 @@ impl<'mir, 'tcx> Qualifs<'mir, 'tcx> {
}
}
struct LocalReturnTyVisitor<'a, 'mir, 'tcx> {
kind: LocalKind,
checker: &'a mut Checker<'mir, 'tcx>,
}
impl<'a, 'mir, 'tcx> TypeVisitor<TyCtxt<'tcx>> for LocalReturnTyVisitor<'a, 'mir, 'tcx> {
fn visit_ty(&mut self, t: Ty<'tcx>) {
match t.kind() {
ty::FnPtr(..) => {}
ty::Ref(_, _, hir::Mutability::Mut) => {
self.checker.check_op(ops::mut_ref::MutRef(self.kind));
t.super_visit_with(self)
}
_ => t.super_visit_with(self),
}
}
}
pub struct Checker<'mir, 'tcx> {
ccx: &'mir ConstCx<'mir, 'tcx>,
qualifs: Qualifs<'mir, 'tcx>,
@ -230,25 +211,6 @@ impl<'mir, 'tcx> Checker<'mir, 'tcx> {
return;
}
// The local type and predicate checks are not free and only relevant for `const fn`s.
if self.const_kind() == hir::ConstContext::ConstFn {
for (idx, local) in body.local_decls.iter_enumerated() {
// Handle the return place below.
if idx == RETURN_PLACE {
continue;
}
self.span = local.source_info.span;
self.check_local_or_return_ty(local.ty, idx);
}
// impl trait is gone in MIR, so check the return type of a const fn by its signature
// instead of the type of the return place.
self.span = body.local_decls[RETURN_PLACE].source_info.span;
let return_ty = self.ccx.fn_sig().output();
self.check_local_or_return_ty(return_ty.skip_binder(), RETURN_PLACE);
}
if !tcx.has_attr(def_id, sym::rustc_do_not_const_check) {
self.visit_body(body);
}
@ -358,16 +320,11 @@ impl<'mir, 'tcx> Checker<'mir, 'tcx> {
self.check_op_spanned(ops::StaticAccess, span)
}
fn check_local_or_return_ty(&mut self, ty: Ty<'tcx>, local: Local) {
let kind = self.body.local_kind(local);
let mut visitor = LocalReturnTyVisitor { kind, checker: self };
visitor.visit_ty(ty);
}
fn check_mut_borrow(&mut self, place: &Place<'_>, kind: hir::BorrowKind) {
match self.const_kind() {
/// Returns whether this place can possibly escape the evaluation of the current const/static
/// initializer. The check assumes that all already existing pointers and references point to
/// non-escaping places.
fn place_may_escape(&mut self, place: &Place<'_>) -> bool {
let is_transient = match self.const_kind() {
// In a const fn all borrows are transient or point to the places given via
// references in the arguments (so we already checked them with
// TransientMutBorrow/MutBorrow as appropriate).
@ -375,7 +332,7 @@ impl<'mir, 'tcx> Checker<'mir, 'tcx> {
// NOTE: Once we have heap allocations during CTFE we need to figure out
// how to prevent `const fn` to create long-lived allocations that point
// to mutable memory.
hir::ConstContext::ConstFn => self.check_op(ops::TransientMutBorrow(kind)),
hir::ConstContext::ConstFn => true,
_ => {
// For indirect places, we are not creating a new permanent borrow, it's just as
// transient as the already existing one. For reborrowing references this is handled
@ -387,15 +344,16 @@ impl<'mir, 'tcx> Checker<'mir, 'tcx> {
// value of the constant.
// Note: This is only sound if every local that has a `StorageDead` has a
// `StorageDead` in every control flow path leading to a `return` terminator.
// The good news is that interning will detect if any unexpected mutable
// pointer slips through.
if place.is_indirect() || self.local_is_transient(place.local) {
self.check_op(ops::TransientMutBorrow(kind));
} else {
self.check_op(ops::MutBorrow(kind));
}
// If anything slips through, there's no safety net -- safe code can create
// references to variants of `!Freeze` enums as long as that variant is `Freeze`, so
// interning can't protect us here. (There *is* a safety net for mutable references
// though, interning will ICE if we miss something here.)
place.is_indirect() || self.local_is_transient(place.local)
}
}
};
// Transient places cannot possibly escape because the place doesn't exist any more at the
// end of evaluation.
!is_transient
}
}
@ -420,47 +378,6 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
fn visit_rvalue(&mut self, rvalue: &Rvalue<'tcx>, location: Location) {
trace!("visit_rvalue: rvalue={:?} location={:?}", rvalue, location);
// Special-case reborrows to be more like a copy of a reference.
// FIXME: this does not actually handle all reborrows. It only detects cases where `*` is the outermost
// projection of the borrowed place, it skips deref'ing raw pointers and it skips `static`.
// All those cases are handled below with shared/mutable borrows.
// Once `const_mut_refs` is stable, we should be able to entirely remove this special case.
// (`const_refs_to_cell` is not needed, we already allow all borrows of indirect places anyway.)
match *rvalue {
Rvalue::Ref(_, kind, place) => {
if let Some(reborrowed_place_ref) = place_as_reborrow(self.tcx, self.body, place) {
let ctx = match kind {
BorrowKind::Shared => {
PlaceContext::NonMutatingUse(NonMutatingUseContext::SharedBorrow)
}
BorrowKind::Fake(_) => {
PlaceContext::NonMutatingUse(NonMutatingUseContext::FakeBorrow)
}
BorrowKind::Mut { .. } => {
PlaceContext::MutatingUse(MutatingUseContext::Borrow)
}
};
self.visit_local(reborrowed_place_ref.local, ctx, location);
self.visit_projection(reborrowed_place_ref, ctx, location);
return;
}
}
Rvalue::RawPtr(mutbl, place) => {
if let Some(reborrowed_place_ref) = place_as_reborrow(self.tcx, self.body, place) {
let ctx = match mutbl {
Mutability::Not => {
PlaceContext::NonMutatingUse(NonMutatingUseContext::RawBorrow)
}
Mutability::Mut => PlaceContext::MutatingUse(MutatingUseContext::RawBorrow),
};
self.visit_local(reborrowed_place_ref.local, ctx, location);
self.visit_projection(reborrowed_place_ref, ctx, location);
return;
}
}
_ => {}
}
self.super_rvalue(rvalue, location);
match rvalue {
@ -494,15 +411,12 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
let is_allowed =
self.const_kind() == hir::ConstContext::Static(hir::Mutability::Mut);
if !is_allowed {
self.check_mut_borrow(
place,
if matches!(rvalue, Rvalue::Ref(..)) {
hir::BorrowKind::Ref
} else {
hir::BorrowKind::Raw
},
);
if !is_allowed && self.place_may_escape(place) {
self.check_op(ops::EscapingMutBorrow(if matches!(rvalue, Rvalue::Ref(..)) {
hir::BorrowKind::Ref
} else {
hir::BorrowKind::Raw
}));
}
}
@ -514,40 +428,8 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
place.as_ref(),
);
// If the place is indirect, this is basically a reborrow. We have a reborrow
// special case above, but for raw pointers and pointers/references to `static` and
// when the `*` is not the first projection, `place_as_reborrow` does not recognize
// them as such, so we end up here. This should probably be considered a
// `TransientCellBorrow` (we consider the equivalent mutable case a
// `TransientMutBorrow`), but such reborrows got accidentally stabilized already and
// it is too much of a breaking change to take back.
if borrowed_place_has_mut_interior && !place.is_indirect() {
match self.const_kind() {
// In a const fn all borrows are transient or point to the places given via
// references in the arguments (so we already checked them with
// TransientCellBorrow/CellBorrow as appropriate).
// The borrow checker guarantees that no new non-transient borrows are created.
// NOTE: Once we have heap allocations during CTFE we need to figure out
// how to prevent `const fn` to create long-lived allocations that point
// to (interior) mutable memory.
hir::ConstContext::ConstFn => self.check_op(ops::TransientCellBorrow),
_ => {
// Locals with StorageDead are definitely not part of the final constant value, and
// it is thus inherently safe to permit such locals to have their
// address taken as we can't end up with a reference to them in the
// final value.
// Note: This is only sound if every local that has a `StorageDead` has a
// `StorageDead` in every control flow path leading to a `return` terminator.
// If anything slips through, there's no safety net -- safe code can create
// references to variants of `!Freeze` enums as long as that variant is `Freeze`,
// so interning can't protect us here.
if self.local_is_transient(place.local) {
self.check_op(ops::TransientCellBorrow);
} else {
self.check_op(ops::CellBorrow);
}
}
}
if borrowed_place_has_mut_interior && self.place_may_escape(place) {
self.check_op(ops::EscapingCellBorrow);
}
}
@ -636,58 +518,6 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
}
}
}
fn visit_projection_elem(
&mut self,
place_ref: PlaceRef<'tcx>,
elem: PlaceElem<'tcx>,
context: PlaceContext,
location: Location,
) {
trace!(
"visit_projection_elem: place_ref={:?} elem={:?} \
context={:?} location={:?}",
place_ref, elem, context, location,
);
self.super_projection_elem(place_ref, elem, context, location);
match elem {
ProjectionElem::Deref => {
let base_ty = place_ref.ty(self.body, self.tcx).ty;
if base_ty.is_unsafe_ptr() {
if place_ref.projection.is_empty() {
let decl = &self.body.local_decls[place_ref.local];
// If this is a static, then this is not really dereferencing a pointer,
// just directly accessing a static. That is not subject to any feature
// gates (except for the one about whether statics can even be used, but
// that is checked already by `visit_operand`).
if let LocalInfo::StaticRef { .. } = *decl.local_info() {
return;
}
}
// `*const T` is stable, `*mut T` is not
if !base_ty.is_mutable_ptr() {
return;
}
self.check_op(ops::RawMutPtrDeref);
}
if context.is_mutating_use() {
self.check_op(ops::MutDeref);
}
}
ProjectionElem::ConstantIndex { .. }
| ProjectionElem::Downcast(..)
| ProjectionElem::OpaqueCast(..)
| ProjectionElem::Subslice { .. }
| ProjectionElem::Subtype(..)
| ProjectionElem::Field(..)
| ProjectionElem::Index(_) => {}
}
}
fn visit_source_info(&mut self, source_info: &SourceInfo) {
trace!("visit_source_info: source_info={:?}", source_info);
@ -984,40 +814,6 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
}
}
fn place_as_reborrow<'tcx>(
tcx: TyCtxt<'tcx>,
body: &Body<'tcx>,
place: Place<'tcx>,
) -> Option<PlaceRef<'tcx>> {
match place.as_ref().last_projection() {
Some((place_base, ProjectionElem::Deref)) => {
// FIXME: why do statics and raw pointers get excluded here? This makes
// some code involving mutable pointers unstable, but it is unclear
// why that code is treated differently from mutable references.
// Once TransientMutBorrow and TransientCellBorrow are stable,
// this can probably be cleaned up without any behavioral changes.
// A borrow of a `static` also looks like `&(*_1)` in the MIR, but `_1` is a `const`
// that points to the allocation for the static. Don't treat these as reborrows.
if body.local_decls[place_base.local].is_ref_to_static() {
None
} else {
// Ensure the type being derefed is a reference and not a raw pointer.
// This is sufficient to prevent an access to a `static mut` from being marked as a
// reborrow, even if the check above were to disappear.
let inner_ty = place_base.ty(body, tcx).ty;
if let ty::Ref(..) = inner_ty.kind() {
return Some(place_base);
} else {
return None;
}
}
}
_ => None,
}
}
fn is_int_bool_float_or_char(ty: Ty<'_>) -> bool {
ty.is_bool() || ty.is_integral() || ty.is_char() || ty.is_floating_point()
}

116
compiler/rustc_const_eval/src/check_consts/ops.rs
View file

@ -8,7 +8,7 @@ use rustc_hir as hir;
use rustc_hir::def_id::DefId;
use rustc_infer::infer::TyCtxtInferExt;
use rustc_infer::traits::{ImplSource, Obligation, ObligationCause};
use rustc_middle::mir::{self, CallSource};
use rustc_middle::mir::CallSource;
use rustc_middle::span_bug;
use rustc_middle::ty::print::{with_no_trimmed_paths, PrintTraitRefExt as _};
use rustc_middle::ty::{
@ -391,27 +391,12 @@ impl<'tcx> NonConstOp<'tcx> for LiveDrop<'tcx> {
}
}
#[derive(Debug)]
/// A borrow of a type that contains an `UnsafeCell` somewhere. The borrow never escapes to
/// the final value of the constant.
pub(crate) struct TransientCellBorrow;
impl<'tcx> NonConstOp<'tcx> for TransientCellBorrow {
fn status_in_item(&self, _: &ConstCx<'_, 'tcx>) -> Status {
Status::Unstable(sym::const_refs_to_cell)
}
fn build_error(&self, ccx: &ConstCx<'_, 'tcx>, span: Span) -> Diag<'tcx> {
ccx.tcx
.sess
.create_feature_err(errors::InteriorMutabilityBorrow { span }, sym::const_refs_to_cell)
}
}
#[derive(Debug)]
/// A borrow of a type that contains an `UnsafeCell` somewhere. The borrow might escape to
/// the final value of the constant, and thus we cannot allow this (for now). We may allow
/// it in the future for static items.
pub(crate) struct CellBorrow;
impl<'tcx> NonConstOp<'tcx> for CellBorrow {
pub(crate) struct EscapingCellBorrow;
impl<'tcx> NonConstOp<'tcx> for EscapingCellBorrow {
fn importance(&self) -> DiagImportance {
// Most likely the code will try to do mutation with these borrows, which
// triggers its own errors. Only show this one if that does not happen.
@ -431,9 +416,9 @@ impl<'tcx> NonConstOp<'tcx> for CellBorrow {
/// This op is for `&mut` borrows in the trailing expression of a constant
/// which uses the "enclosing scopes rule" to leak its locals into anonymous
/// static or const items.
pub(crate) struct MutBorrow(pub hir::BorrowKind);
pub(crate) struct EscapingMutBorrow(pub hir::BorrowKind);
impl<'tcx> NonConstOp<'tcx> for MutBorrow {
impl<'tcx> NonConstOp<'tcx> for EscapingMutBorrow {
fn status_in_item(&self, _ccx: &ConstCx<'_, 'tcx>) -> Status {
Status::Forbidden
}
@ -460,49 +445,6 @@ impl<'tcx> NonConstOp<'tcx> for MutBorrow {
}
}
#[derive(Debug)]
pub(crate) struct TransientMutBorrow(pub hir::BorrowKind);
impl<'tcx> NonConstOp<'tcx> for TransientMutBorrow {
fn status_in_item(&self, _: &ConstCx<'_, 'tcx>) -> Status {
Status::Unstable(sym::const_mut_refs)
}
fn build_error(&self, ccx: &ConstCx<'_, 'tcx>, span: Span) -> Diag<'tcx> {
let kind = ccx.const_kind();
match self.0 {
hir::BorrowKind::Raw => ccx
.tcx
.sess
.create_feature_err(errors::TransientMutRawErr { span, kind }, sym::const_mut_refs),
hir::BorrowKind::Ref => ccx.tcx.sess.create_feature_err(
errors::TransientMutBorrowErr { span, kind },
sym::const_mut_refs,
),
}
}
}
#[derive(Debug)]
pub(crate) struct MutDeref;
impl<'tcx> NonConstOp<'tcx> for MutDeref {
fn status_in_item(&self, _: &ConstCx<'_, 'tcx>) -> Status {
Status::Unstable(sym::const_mut_refs)
}
fn importance(&self) -> DiagImportance {
// Usually a side-effect of a `TransientMutBorrow` somewhere.
DiagImportance::Secondary
}
fn build_error(&self, ccx: &ConstCx<'_, 'tcx>, span: Span) -> Diag<'tcx> {
ccx.tcx.sess.create_feature_err(
errors::MutDerefErr { span, kind: ccx.const_kind() },
sym::const_mut_refs,
)
}
}
/// A call to a `panic()` lang item where the first argument is _not_ a `&str`.
#[derive(Debug)]
pub(crate) struct PanicNonStr;
@ -524,24 +466,6 @@ impl<'tcx> NonConstOp<'tcx> for RawPtrComparison {
}
}
#[derive(Debug)]
pub(crate) struct RawMutPtrDeref;
impl<'tcx> NonConstOp<'tcx> for RawMutPtrDeref {
fn status_in_item(&self, _: &ConstCx<'_, '_>) -> Status {
Status::Unstable(sym::const_mut_refs)
}
#[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
fn build_error(&self, ccx: &ConstCx<'_, 'tcx>, span: Span) -> Diag<'tcx> {
feature_err(
&ccx.tcx.sess,
sym::const_mut_refs,
span,
format!("dereferencing raw mutable pointers in {}s is unstable", ccx.const_kind(),),
)
}
}
/// Casting raw pointer or function pointer to an integer.
/// Not currently intended to ever be allowed, even behind a feature gate: operation depends on
/// allocation base addresses that are not known at compile-time.
@ -588,33 +512,3 @@ impl<'tcx> NonConstOp<'tcx> for ThreadLocalAccess {
ccx.dcx().create_err(errors::ThreadLocalAccessErr { span })
}
}
/// Types that cannot appear in the signature or locals of a `const fn`.
pub(crate) mod mut_ref {
use super::*;
#[derive(Debug)]
pub(crate) struct MutRef(pub mir::LocalKind);
impl<'tcx> NonConstOp<'tcx> for MutRef {
fn status_in_item(&self, _ccx: &ConstCx<'_, 'tcx>) -> Status {
Status::Unstable(sym::const_mut_refs)
}
fn importance(&self) -> DiagImportance {
match self.0 {
mir::LocalKind::Temp => DiagImportance::Secondary,
mir::LocalKind::ReturnPointer | mir::LocalKind::Arg => DiagImportance::Primary,
}
}
#[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
fn build_error(&self, ccx: &ConstCx<'_, 'tcx>, span: Span) -> Diag<'tcx> {
feature_err(
&ccx.tcx.sess,
sym::const_mut_refs,
span,
format!("mutable references are not allowed in {}s", ccx.const_kind()),
)
}
}
}

31
compiler/rustc_const_eval/src/errors.rs
View file

@ -93,30 +93,6 @@ pub(crate) struct PanicNonStrErr {
pub span: Span,
}
#[derive(Diagnostic)]
#[diag(const_eval_mut_deref, code = E0658)]
pub(crate) struct MutDerefErr {
#[primary_span]
pub span: Span,
pub kind: ConstContext,
}
#[derive(Diagnostic)]
#[diag(const_eval_transient_mut_borrow, code = E0658)]
pub(crate) struct TransientMutBorrowErr {
#[primary_span]
pub span: Span,
pub kind: ConstContext,
}
#[derive(Diagnostic)]
#[diag(const_eval_transient_mut_raw, code = E0658)]
pub(crate) struct TransientMutRawErr {
#[primary_span]
pub span: Span,
pub kind: ConstContext,
}
#[derive(Diagnostic)]
#[diag(const_eval_max_num_nodes_in_const)]
pub(crate) struct MaxNumNodesInConstErr {
@ -217,13 +193,6 @@ pub(crate) struct InteriorMutableDataRefer {
pub teach: bool,
}
#[derive(Diagnostic)]
#[diag(const_eval_interior_mutability_borrow)]
pub(crate) struct InteriorMutabilityBorrow {
#[primary_span]
pub span: Span,
}
#[derive(LintDiagnostic)]
#[diag(const_eval_long_running)]
#[note]