nordic-dev.net/rust
nordic-dev.net/rust
2
0
Fork 0
mirror of https://github.com/rust-lang/rust.git synced 2024-11-21 22:34:05 +00:00
Code Issues Packages Projects Releases Wiki Activity

Auto merge of #73153 - ecstatic-morse:revert-71956, r=tmandry

Browse Source 
Revert #71956

...since it caused unsoundness in #73137. Also adds a reduced version of #73137 to the test suite. The addition of the `MaybeInitializedLocals` dataflow analysis has not been reverted, but it is no longer used.

Presumably there is a more targeted fix, but I'm worried that other bugs may be lurking. I'm not yet sure what the root cause of #73137 is.

This will need to get backported to beta.

r? @tmandry
This commit is contained in:
bors 2020-06-09 03:41:43 +00:00
commit ccac43b86b
8 changed files with 415 additions and 138 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
src/librustc_mir/dataflow/impls/borrowed_locals.rs
View File

@ -99,9 +99,6 @@ impl<K> GenKillAnalysis<'tcx> for MaybeBorrowedLocals<K>
where
K: BorrowAnalysisKind<'tcx>,
{
// The generator transform relies on the fact that this analysis does **not** use "before"
// effects.
fn statement_effect(
&self,
trans: &mut impl GenKill<Self::Idx>,

3
src/librustc_mir/dataflow/impls/init_locals.rs
View File

@ -33,9 +33,6 @@ impl dataflow::AnalysisDomain<'tcx> for MaybeInitializedLocals {
}
impl dataflow::GenKillAnalysis<'tcx> for MaybeInitializedLocals {
// The generator transform relies on the fact that this analysis does **not** use "before"
// effects.
fn statement_effect(
&self,
trans: &mut impl GenKill<Self::Idx>,

2
src/librustc_mir/dataflow/impls/mod.rs
View File

@ -30,7 +30,7 @@ pub use self::borrowed_locals::{MaybeBorrowedLocals, MaybeMutBorrowedLocals};
pub use self::borrows::Borrows;
pub use self::init_locals::MaybeInitializedLocals;
pub use self::liveness::MaybeLiveLocals;
pub use self::storage_liveness::MaybeStorageLive;
pub use self::storage_liveness::{MaybeRequiresStorage, MaybeStorageLive};
/// `MaybeInitializedPlaces` tracks all places that might be
/// initialized upon reaching a particular point in the control flow

234
src/librustc_mir/dataflow/impls/storage_liveness.rs
View File

@ -1,9 +1,11 @@
pub use super::*;
use crate::dataflow::BottomValue;
use crate::dataflow::{self, GenKill};
use crate::dataflow::{self, GenKill, Results, ResultsRefCursor};
use crate::util::storage::AlwaysLiveLocals;
use rustc_middle::mir::visit::{NonMutatingUseContext, PlaceContext, Visitor};
use rustc_middle::mir::*;
use std::cell::RefCell;
#[derive(Clone)]
pub struct MaybeStorageLive {
@ -76,3 +78,233 @@ impl BottomValue for MaybeStorageLive {
/// bottom = dead
const BOTTOM_VALUE: bool = false;
}
type BorrowedLocalsResults<'a, 'tcx> = ResultsRefCursor<'a, 'a, 'tcx, MaybeBorrowedLocals>;
/// Dataflow analysis that determines whether each local requires storage at a
/// given location; i.e. whether its storage can go away without being observed.
pub struct MaybeRequiresStorage<'mir, 'tcx> {
body: &'mir Body<'tcx>,
borrowed_locals: RefCell<BorrowedLocalsResults<'mir, 'tcx>>,
}
impl<'mir, 'tcx> MaybeRequiresStorage<'mir, 'tcx> {
pub fn new(
body: &'mir Body<'tcx>,
borrowed_locals: &'mir Results<'tcx, MaybeBorrowedLocals>,
) -> Self {
MaybeRequiresStorage {
body,
borrowed_locals: RefCell::new(ResultsRefCursor::new(&body, borrowed_locals)),
}
}
}
impl<'mir, 'tcx> dataflow::AnalysisDomain<'tcx> for MaybeRequiresStorage<'mir, 'tcx> {
type Idx = Local;
const NAME: &'static str = "requires_storage";
fn bits_per_block(&self, body: &mir::Body<'tcx>) -> usize {
body.local_decls.len()
}
fn initialize_start_block(&self, body: &mir::Body<'tcx>, on_entry: &mut BitSet<Self::Idx>) {
// The resume argument is live on function entry (we don't care about
// the `self` argument)
for arg in body.args_iter().skip(1) {
on_entry.insert(arg);
}
}
}
impl<'mir, 'tcx> dataflow::GenKillAnalysis<'tcx> for MaybeRequiresStorage<'mir, 'tcx> {
fn before_statement_effect(
&self,
trans: &mut impl GenKill<Self::Idx>,
stmt: &mir::Statement<'tcx>,
loc: Location,
) {
// If a place is borrowed in a statement, it needs storage for that statement.
self.borrowed_locals.borrow().analysis().statement_effect(trans, stmt, loc);
match &stmt.kind {
StatementKind::StorageDead(l) => trans.kill(*l),
// If a place is assigned to in a statement, it needs storage for that statement.
StatementKind::Assign(box (place, _))
| StatementKind::SetDiscriminant { box place, .. } => {
trans.gen(place.local);
}
StatementKind::LlvmInlineAsm(asm) => {
for place in &*asm.outputs {
trans.gen(place.local);
}
}
// Nothing to do for these. Match exhaustively so this fails to compile when new
// variants are added.
StatementKind::AscribeUserType(..)
| StatementKind::FakeRead(..)
| StatementKind::Nop
| StatementKind::Retag(..)
| StatementKind::StorageLive(..) => {}
}
}
fn statement_effect(
&self,
trans: &mut impl GenKill<Self::Idx>,
_: &mir::Statement<'tcx>,
loc: Location,
) {
// If we move from a place then only stops needing storage *after*
// that statement.
self.check_for_move(trans, loc);
}
fn before_terminator_effect(
&self,
trans: &mut impl GenKill<Self::Idx>,
terminator: &mir::Terminator<'tcx>,
loc: Location,
) {
// If a place is borrowed in a terminator, it needs storage for that terminator.
self.borrowed_locals.borrow().analysis().terminator_effect(trans, terminator, loc);
match &terminator.kind {
TerminatorKind::Call { destination: Some((place, _)), .. } => {
trans.gen(place.local);
}
// Note that we do *not* gen the `resume_arg` of `Yield` terminators. The reason for
// that is that a `yield` will return from the function, and `resume_arg` is written
// only when the generator is later resumed. Unlike `Call`, this doesn't require the
// place to have storage *before* the yield, only after.
TerminatorKind::Yield { .. } => {}
TerminatorKind::InlineAsm { operands, .. } => {
for op in operands {
match op {
InlineAsmOperand::Out { place, .. }
| InlineAsmOperand::InOut { out_place: place, .. } => {
if let Some(place) = place {
trans.gen(place.local);
}
}
InlineAsmOperand::In { .. }
| InlineAsmOperand::Const { .. }
| InlineAsmOperand::SymFn { .. }
| InlineAsmOperand::SymStatic { .. } => {}
}
}
}
// Nothing to do for these. Match exhaustively so this fails to compile when new
// variants are added.
TerminatorKind::Call { destination: None, .. }
| TerminatorKind::Abort
| TerminatorKind::Assert { .. }
| TerminatorKind::Drop { .. }
| TerminatorKind::DropAndReplace { .. }
| TerminatorKind::FalseEdge { .. }
| TerminatorKind::FalseUnwind { .. }
| TerminatorKind::GeneratorDrop
| TerminatorKind::Goto { .. }
| TerminatorKind::Resume
| TerminatorKind::Return
| TerminatorKind::SwitchInt { .. }
| TerminatorKind::Unreachable => {}
}
}
fn terminator_effect(
&self,
trans: &mut impl GenKill<Self::Idx>,
terminator: &mir::Terminator<'tcx>,
loc: Location,
) {
match &terminator.kind {
// For call terminators the destination requires storage for the call
// and after the call returns successfully, but not after a panic.
// Since `propagate_call_unwind` doesn't exist, we have to kill the
// destination here, and then gen it again in `call_return_effect`.
TerminatorKind::Call { destination: Some((place, _)), .. } => {
trans.kill(place.local);
}
// Nothing to do for these. Match exhaustively so this fails to compile when new
// variants are added.
TerminatorKind::Call { destination: None, .. }
| TerminatorKind::Yield { .. }
| TerminatorKind::Abort
| TerminatorKind::Assert { .. }
| TerminatorKind::Drop { .. }
| TerminatorKind::DropAndReplace { .. }
| TerminatorKind::FalseEdge { .. }
| TerminatorKind::FalseUnwind { .. }
| TerminatorKind::GeneratorDrop
| TerminatorKind::Goto { .. }
| TerminatorKind::InlineAsm { .. }
| TerminatorKind::Resume
| TerminatorKind::Return
| TerminatorKind::SwitchInt { .. }
| TerminatorKind::Unreachable => {}
}
self.check_for_move(trans, loc);
}
fn call_return_effect(
&self,
trans: &mut impl GenKill<Self::Idx>,
_block: BasicBlock,
_func: &mir::Operand<'tcx>,
_args: &[mir::Operand<'tcx>],
return_place: mir::Place<'tcx>,
) {
trans.gen(return_place.local);
}
fn yield_resume_effect(
&self,
trans: &mut impl GenKill<Self::Idx>,
_resume_block: BasicBlock,
resume_place: mir::Place<'tcx>,
) {
trans.gen(resume_place.local);
}
}
impl<'mir, 'tcx> MaybeRequiresStorage<'mir, 'tcx> {
/// Kill locals that are fully moved and have not been borrowed.
fn check_for_move(&self, trans: &mut impl GenKill<Local>, loc: Location) {
let mut visitor = MoveVisitor { trans, borrowed_locals: &self.borrowed_locals };
visitor.visit_location(&self.body, loc);
}
}
impl<'mir, 'tcx> BottomValue for MaybeRequiresStorage<'mir, 'tcx> {
/// bottom = dead
const BOTTOM_VALUE: bool = false;
}
struct MoveVisitor<'a, 'mir, 'tcx, T> {
borrowed_locals: &'a RefCell<BorrowedLocalsResults<'mir, 'tcx>>,
trans: &'a mut T,
}
impl<'a, 'mir, 'tcx, T> Visitor<'tcx> for MoveVisitor<'a, 'mir, 'tcx, T>
where
T: GenKill<Local>,
{
fn visit_local(&mut self, local: &Local, context: PlaceContext, loc: Location) {
if PlaceContext::NonMutatingUse(NonMutatingUseContext::Move) == context {
let mut borrowed_locals = self.borrowed_locals.borrow_mut();
borrowed_locals.seek_before_primary_effect(loc);
if !borrowed_locals.contains(*local) {
self.trans.kill(*local);
}
}
}
}

265
src/librustc_mir/transform/generator.rs
View File

@ -50,7 +50,7 @@
//! Otherwise it drops all the values in scope at the last suspension point.
use crate::dataflow::impls::{
MaybeBorrowedLocals, MaybeInitializedLocals, MaybeLiveLocals, MaybeStorageLive,
MaybeBorrowedLocals, MaybeLiveLocals, MaybeRequiresStorage, MaybeStorageLive,
};
use crate::dataflow::{self, Analysis};
use crate::transform::no_landing_pads::no_landing_pads;
@ -444,80 +444,86 @@ fn locals_live_across_suspend_points(
movable: bool,
) -> LivenessInfo {
let def_id = source.def_id();
let body_ref: &Body<'_> = &body;
// Calculate when MIR locals have live storage. This gives us an upper bound of their
// lifetimes.
let mut storage_live = MaybeStorageLive::new(always_live_locals.clone())
.into_engine(tcx, body, def_id)
.into_engine(tcx, body_ref, def_id)
.iterate_to_fixpoint()
.into_results_cursor(body);
.into_results_cursor(body_ref);
let mut init = MaybeInitializedLocals
.into_engine(tcx, body, def_id)
// Calculate the MIR locals which have been previously
// borrowed (even if they are still active).
let borrowed_locals_results =
MaybeBorrowedLocals::all_borrows().into_engine(tcx, body_ref, def_id).iterate_to_fixpoint();
let mut borrowed_locals_cursor =
dataflow::ResultsCursor::new(body_ref, &borrowed_locals_results);
// Calculate the MIR locals that we actually need to keep storage around
// for.
let requires_storage_results = MaybeRequiresStorage::new(body, &borrowed_locals_results)
.into_engine(tcx, body_ref, def_id)
.iterate_to_fixpoint();
let mut requires_storage_cursor =
dataflow::ResultsCursor::new(body_ref, &requires_storage_results);
// Calculate the liveness of MIR locals ignoring borrows.
let mut liveness = MaybeLiveLocals
.into_engine(tcx, body_ref, def_id)
.iterate_to_fixpoint()
.into_results_cursor(body);
let mut live = MaybeLiveLocals
.into_engine(tcx, body, def_id)
.iterate_to_fixpoint()
.into_results_cursor(body);
let mut borrowed = MaybeBorrowedLocals::all_borrows()
.into_engine(tcx, body, def_id)
.iterate_to_fixpoint()
.into_results_cursor(body);
// Liveness across yield points is determined by the following boolean equation, where `live`,
// `init` and `borrowed` come from dataflow and `movable` is a property of the generator.
// Movable generators do not allow borrows to live across yield points, so they don't need to
// store a local simply because it is borrowed.
//
// live_across_yield := (live & init) | (!movable & borrowed)
//
let mut locals_live_across_yield_point = |block| {
live.seek_to_block_end(block);
let mut live_locals = live.get().clone();
init.seek_to_block_end(block);
live_locals.intersect(init.get());
if !movable {
borrowed.seek_to_block_end(block);
live_locals.union(borrowed.get());
}
live_locals
};
.into_results_cursor(body_ref);
let mut storage_liveness_map = IndexVec::from_elem(None, body.basic_blocks());
let mut live_locals_at_suspension_points = Vec::new();
let mut live_locals_at_any_suspension_point = BitSet::new_empty(body.local_decls.len());
for (block, data) in body.basic_blocks().iter_enumerated() {
if !matches!(data.terminator().kind, TerminatorKind::Yield { .. }) {
continue;
if let TerminatorKind::Yield { .. } = data.terminator().kind {
let loc = Location { block, statement_index: data.statements.len() };
liveness.seek_to_block_end(block);
let mut live_locals = liveness.get().clone();
if !movable {
// The `liveness` variable contains the liveness of MIR locals ignoring borrows.
// This is correct for movable generators since borrows cannot live across
// suspension points. However for immovable generators we need to account for
// borrows, so we conseratively assume that all borrowed locals are live until
// we find a StorageDead statement referencing the locals.
// To do this we just union our `liveness` result with `borrowed_locals`, which
// contains all the locals which has been borrowed before this suspension point.
// If a borrow is converted to a raw reference, we must also assume that it lives
// forever. Note that the final liveness is still bounded by the storage liveness
// of the local, which happens using the `intersect` operation below.
borrowed_locals_cursor.seek_before_primary_effect(loc);
live_locals.union(borrowed_locals_cursor.get());
}
// Store the storage liveness for later use so we can restore the state
// after a suspension point
storage_live.seek_before_primary_effect(loc);
storage_liveness_map[block] = Some(storage_live.get().clone());
// Locals live are live at this point only if they are used across
// suspension points (the `liveness` variable)
// and their storage is required (the `storage_required` variable)
requires_storage_cursor.seek_before_primary_effect(loc);
live_locals.intersect(requires_storage_cursor.get());
// The generator argument is ignored.
live_locals.remove(SELF_ARG);
debug!("loc = {:?}, live_locals = {:?}", loc, live_locals);
// Add the locals live at this suspension point to the set of locals which live across
// any suspension points
live_locals_at_any_suspension_point.union(&live_locals);
live_locals_at_suspension_points.push(live_locals);
}
// Store the storage liveness for later use so we can restore the state
// after a suspension point
storage_live.seek_to_block_end(block);
storage_liveness_map[block] = Some(storage_live.get().clone());
let mut live_locals = locals_live_across_yield_point(block);
// The combination of `MaybeInitializedLocals` and `MaybeBorrowedLocals` should be strictly
// more precise than `MaybeStorageLive` because they handle `StorageDead` themselves. This
// assumes that the MIR forbids locals from being initialized/borrowed before reaching
// `StorageLive`.
debug_assert!(storage_live.get().superset(&live_locals));
// Ignore the generator's `self` argument since it is handled seperately.
live_locals.remove(SELF_ARG);
debug!("block = {:?}, live_locals = {:?}", block, live_locals);
live_locals_at_any_suspension_point.union(&live_locals);
live_locals_at_suspension_points.push(live_locals);
}
debug!("live_locals_anywhere = {:?}", live_locals_at_any_suspension_point);
// Renumber our liveness_map bitsets to include only the locals we are
@ -528,11 +534,10 @@ fn locals_live_across_suspend_points(
.collect();
let storage_conflicts = compute_storage_conflicts(
body,
body_ref,
&live_locals_at_any_suspension_point,
always_live_locals.clone(),
init,
borrowed,
requires_storage_results,
);
LivenessInfo {
@ -564,37 +569,6 @@ fn renumber_bitset(
out
}
/// Record conflicts between locals at the current dataflow cursor positions.
///
/// You need to seek the cursors before calling this function.
fn record_conflicts_at_curr_loc(
local_conflicts: &mut BitMatrix<Local, Local>,
init: &dataflow::ResultsCursor<'mir, 'tcx, MaybeInitializedLocals>,
borrowed: &dataflow::ResultsCursor<'mir, 'tcx, MaybeBorrowedLocals>,
) {
// A local requires storage if it is initialized or borrowed. For now, a local
// becomes uninitialized if it is moved from, but is still considered "borrowed".
//
// requires_storage := init | borrowed
//
// Just like when determining what locals are live at yield points, there is no need
// to look at storage liveness here, since `init | borrowed` is strictly more precise.
//
// FIXME: This function is called in a loop, so it might be better to pass in a temporary
// bitset rather than cloning here.
let mut requires_storage = init.get().clone();
requires_storage.union(borrowed.get());
for local in requires_storage.iter() {
local_conflicts.union_row_with(&requires_storage, local);
}
// `>1` because the `self` argument always requires storage.
if requires_storage.count() > 1 {
trace!("requires_storage={:?}", requires_storage);
}
}
/// For every saved local, looks for which locals are StorageLive at the same
/// time. Generates a bitset for every local of all the other locals that may be
/// StorageLive simultaneously with that local. This is used in the layout
@ -603,45 +577,30 @@ fn compute_storage_conflicts(
body: &'mir Body<'tcx>,
stored_locals: &BitSet<Local>,
always_live_locals: storage::AlwaysLiveLocals,
mut init: dataflow::ResultsCursor<'mir, 'tcx, MaybeInitializedLocals>,
mut borrowed: dataflow::ResultsCursor<'mir, 'tcx, MaybeBorrowedLocals>,
requires_storage: dataflow::Results<'tcx, MaybeRequiresStorage<'mir, 'tcx>>,
) -> BitMatrix<GeneratorSavedLocal, GeneratorSavedLocal> {
debug!("compute_storage_conflicts({:?})", body.span);
assert_eq!(body.local_decls.len(), stored_locals.domain_size());
// Locals that are always live conflict with all other locals.
//
// FIXME: Why do we need to handle locals without `Storage{Live,Dead}` specially here?
// Shouldn't it be enough to know whether they are initialized?
let always_live_locals = always_live_locals.into_inner();
let mut local_conflicts = BitMatrix::from_row_n(&always_live_locals, body.local_decls.len());
debug!("compute_storage_conflicts({:?})", body.span);
debug!("always_live = {:?}", always_live_locals);
// Visit every reachable statement and terminator. The exact order does not matter. When two
// locals are live at the same point in time, add an entry in the conflict matrix.
for (block, data) in traversal::preorder(body) {
// Ignore unreachable blocks.
if data.terminator().kind == TerminatorKind::Unreachable {
continue;
}
// Locals that are always live or ones that need to be stored across
// suspension points are not eligible for overlap.
let mut ineligible_locals = always_live_locals.into_inner();
ineligible_locals.intersect(stored_locals);
// Observe the dataflow state *before* all possible locations (statement or terminator) in
// each basic block...
for statement_index in 0..=data.statements.len() {
let loc = Location { block, statement_index };
trace!("record conflicts at {:?}", loc);
init.seek_before_primary_effect(loc);
borrowed.seek_before_primary_effect(loc);
record_conflicts_at_curr_loc(&mut local_conflicts, &init, &borrowed);
}
// Compute the storage conflicts for all eligible locals.
let mut visitor = StorageConflictVisitor {
body,
stored_locals: &stored_locals,
local_conflicts: BitMatrix::from_row_n(&ineligible_locals, body.local_decls.len()),
};
// ...and then observe the state *after* the terminator effect is applied. As long as
// neither `init` nor `borrowed` has a "before" effect, we will observe all possible
// dataflow states here or in the loop above.
trace!("record conflicts at end of {:?}", block);
init.seek_to_block_end(block);
borrowed.seek_to_block_end(block);
record_conflicts_at_curr_loc(&mut local_conflicts, &init, &borrowed);
}
// Visit only reachable basic blocks. The exact order is not important.
let reachable_blocks = traversal::preorder(body).map(|(bb, _)| bb);
requires_storage.visit_with(body, reachable_blocks, &mut visitor);
let local_conflicts = visitor.local_conflicts;
// Compress the matrix using only stored locals (Local -> GeneratorSavedLocal).
//
@ -653,7 +612,7 @@ fn compute_storage_conflicts(
let mut storage_conflicts = BitMatrix::new(stored_locals.count(), stored_locals.count());
for (idx_a, local_a) in stored_locals.iter().enumerate() {
let saved_local_a = GeneratorSavedLocal::new(idx_a);
if always_live_locals.contains(local_a) {
if ineligible_locals.contains(local_a) {
// Conflicts with everything.
storage_conflicts.insert_all_into_row(saved_local_a);
} else {
@ -669,6 +628,56 @@ fn compute_storage_conflicts(
storage_conflicts
}
struct StorageConflictVisitor<'mir, 'tcx, 's> {
body: &'mir Body<'tcx>,
stored_locals: &'s BitSet<Local>,
// FIXME(tmandry): Consider using sparse bitsets here once we have good
// benchmarks for generators.
local_conflicts: BitMatrix<Local, Local>,
}
impl dataflow::ResultsVisitor<'mir, 'tcx> for StorageConflictVisitor<'mir, 'tcx, '_> {
type FlowState = BitSet<Local>;
fn visit_statement_before_primary_effect(
&mut self,
state: &Self::FlowState,
_statement: &'mir Statement<'tcx>,
loc: Location,
) {
self.apply_state(state, loc);
}
fn visit_terminator_before_primary_effect(
&mut self,
state: &Self::FlowState,
_terminator: &'mir Terminator<'tcx>,
loc: Location,
) {
self.apply_state(state, loc);
}
}
impl<'body, 'tcx, 's> StorageConflictVisitor<'body, 'tcx, 's> {
fn apply_state(&mut self, flow_state: &BitSet<Local>, loc: Location) {
// Ignore unreachable blocks.
if self.body.basic_blocks()[loc.block].terminator().kind == TerminatorKind::Unreachable {
return;
}
let mut eligible_storage_live = flow_state.clone();
eligible_storage_live.intersect(&self.stored_locals);
for local in eligible_storage_live.iter() {
self.local_conflicts.union_row_with(&eligible_storage_live, local);
}
if eligible_storage_live.count() > 1 {
trace!("at {:?}, eligible_storage_live={:?}", loc, eligible_storage_live);
}
}
}
/// Validates the typeck view of the generator against the actual set of types retained between
/// yield points.
fn sanitize_witness<'tcx>(

2
src/test/ui/async-await/async-fn-size-moved-locals.rs
View File

@ -114,5 +114,5 @@ fn main() {
assert_eq!(1026, std::mem::size_of_val(&single_with_noop()));
assert_eq!(3078, std::mem::size_of_val(&joined()));
assert_eq!(3079, std::mem::size_of_val(&joined_with_noop()));
assert_eq!(6157, std::mem::size_of_val(&mixed_sizes()));
assert_eq!(7181, std::mem::size_of_val(&mixed_sizes()));
}

42
src/test/ui/async-await/issue-73137.rs Normal file
View File

@ -0,0 +1,42 @@
// Regression test for <https://github.com/rust-lang/rust/issues/73137>
// run-pass
// edition:2018
#![allow(dead_code)]
#![feature(wake_trait)]
use std::future::Future;
use std::task::{Waker, Wake, Context};
use std::sync::Arc;
struct DummyWaker;
impl Wake for DummyWaker {
fn wake(self: Arc<Self>) {}
}
struct Foo {
a: usize,
b: &'static u32,
}
#[inline(never)]
fn nop<T>(_: T) {}
fn main() {
let mut fut = Box::pin(async {
let action = Foo {
b: &42,
a: async { 0 }.await,
};
// An error in the generator transform caused `b` to be overwritten with `a` when `b` was
// borrowed.
nop(&action.b);
assert_ne!(0usize, unsafe { std::mem::transmute(action.b) });
async {}.await;
});
let waker = Waker::from(Arc::new(DummyWaker));
let mut cx = Context::from_waker(&waker);
let _ = fut.as_mut().poll(&mut cx);
}

2
src/test/ui/generator/size-moved-locals.rs
View File

@ -72,6 +72,6 @@ fn overlap_x_and_y() -> impl Generator<Yield = (), Return = ()> {
fn main() {
assert_eq!(1025, std::mem::size_of_val(&move_before_yield()));
assert_eq!(1026, std::mem::size_of_val(&move_before_yield_with_noop()));
assert_eq!(1027, std::mem::size_of_val(&overlap_move_points()));
assert_eq!(2051, std::mem::size_of_val(&overlap_move_points()));
assert_eq!(1026, std::mem::size_of_val(&overlap_x_and_y()));
}