Auto merge of #86445 - sexxi-goose:box_fix, r=nikomatsakis
2229: Capture box completely in move closures Even if the content from box is used in a sharef-ref context, we capture the box entirerly. This is motivated by: 1) We only capture data that is on the stack. 2) Capturing data from within the box might end up moving more data than the user anticipated. Closes https://github.com/rust-lang/project-rfc-2229/issues/50 r? `@nikomatsakis`
This commit is contained in:
bors
commit
a4f832b275
3 changed files with 178 additions and 15 deletions
|
|
@ -167,7 +167,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
|
|||
);
|
||||
self.log_capture_analysis_first_pass(closure_def_id, &delegate.capture_information, span);
|
||||
|
||||
self.compute_min_captures(closure_def_id, delegate.capture_information);
|
||||
self.compute_min_captures(closure_def_id, capture_clause, delegate.capture_information);
|
||||
|
||||
let closure_hir_id = self.tcx.hir().local_def_id_to_hir_id(local_def_id);
|
||||
|
||||
|
|
@ -200,7 +200,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
|
|||
}
|
||||
|
||||
// This will update the min captures based on this new fake information.
|
||||
self.compute_min_captures(closure_def_id, capture_information);
|
||||
self.compute_min_captures(closure_def_id, capture_clause, capture_information);
|
||||
}
|
||||
|
||||
if let Some(closure_substs) = infer_kind {
|
||||
|
|
@ -213,7 +213,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
|
|||
// If we have an origin, store it.
|
||||
if let Some(origin) = delegate.current_origin.clone() {
|
||||
let origin = if enable_precise_capture(self.tcx, span) {
|
||||
(origin.0, restrict_capture_precision(origin.1))
|
||||
(origin.0, restrict_capture_precision(capture_clause, origin.1))
|
||||
} else {
|
||||
(origin.0, Place { projections: vec![], ..origin.1 })
|
||||
};
|
||||
|
|
@ -368,6 +368,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
|
|||
fn compute_min_captures(
|
||||
&self,
|
||||
closure_def_id: DefId,
|
||||
capture_clause: hir::CaptureBy,
|
||||
capture_information: InferredCaptureInformation<'tcx>,
|
||||
) {
|
||||
if capture_information.is_empty() {
|
||||
|
|
@ -385,7 +386,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
|
|||
base => bug!("Expected upvar, found={:?}", base),
|
||||
};
|
||||
|
||||
let place = restrict_capture_precision(place);
|
||||
let place = restrict_capture_precision(capture_clause, place);
|
||||
|
||||
let min_cap_list = match root_var_min_capture_list.get_mut(&var_hir_id) {
|
||||
None => {
|
||||
|
|
@ -1590,7 +1591,7 @@ impl<'a, 'tcx> euv::Delegate<'tcx> for InferBorrowKind<'a, 'tcx> {
|
|||
if let PlaceBase::Upvar(_) = place.base {
|
||||
// We need to restrict Fake Read precision to avoid fake reading unsafe code,
|
||||
// such as deref of a raw pointer.
|
||||
let place = restrict_capture_precision(place);
|
||||
let place = restrict_capture_precision(self.capture_clause, place);
|
||||
let place =
|
||||
restrict_repr_packed_field_ref_capture(self.fcx.tcx, self.fcx.param_env, &place);
|
||||
self.fake_reads.push((place, cause, diag_expr_id));
|
||||
|
|
@ -1625,11 +1626,15 @@ impl<'a, 'tcx> euv::Delegate<'tcx> for InferBorrowKind<'a, 'tcx> {
|
|||
place_with_id, diag_expr_id, bk
|
||||
);
|
||||
|
||||
// We only want repr packed restriction to be applied to reading references into a packed
|
||||
// struct, and not when the data is being moved. There for we call this method here instead
|
||||
// of in `restrict_capture_precision`.
|
||||
let place = restrict_repr_packed_field_ref_capture(
|
||||
self.fcx.tcx,
|
||||
self.fcx.param_env,
|
||||
&place_with_id.place,
|
||||
);
|
||||
|
||||
let place_with_id = PlaceWithHirId { place, ..*place_with_id };
|
||||
|
||||
if !self.capture_information.contains_key(&place_with_id.place) {
|
||||
|
|
@ -1654,11 +1659,46 @@ impl<'a, 'tcx> euv::Delegate<'tcx> for InferBorrowKind<'a, 'tcx> {
|
|||
}
|
||||
}
|
||||
|
||||
/// Deref of a box isn't captured in move clousres. This is motivated by:
|
||||
/// 1. We only want to capture data that is on the stack
|
||||
/// 2. One motivation for the user to use a box might be to reduce the amount of data that gets
|
||||
/// moved (if size of pointer < size of data). We want to make sure that this optimization that
|
||||
/// the user made is respected.
|
||||
fn restrict_precision_for_box<'tcx>(
|
||||
capture_clause: hir::CaptureBy,
|
||||
mut place: Place<'tcx>,
|
||||
) -> Place<'tcx> {
|
||||
match capture_clause {
|
||||
hir::CaptureBy::Ref => {}
|
||||
hir::CaptureBy::Value => {
|
||||
if ty::TyS::is_box(place.base_ty) {
|
||||
place.projections.truncate(0);
|
||||
} else {
|
||||
// Either the box is the last access or there is a deref applied on the box
|
||||
// In either case we want to stop at the box.
|
||||
let pos = place.projections.iter().position(|proj| ty::TyS::is_box(proj.ty));
|
||||
match pos {
|
||||
None => {}
|
||||
Some(idx) => {
|
||||
place.projections.truncate(idx + 1);
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
place
|
||||
}
|
||||
|
||||
/// Truncate projections so that following rules are obeyed by the captured `place`:
|
||||
/// - No projections are applied to raw pointers, since these require unsafe blocks. We capture
|
||||
/// them completely.
|
||||
/// - No Index projections are captured, since arrays are captured completely.
|
||||
fn restrict_capture_precision<'tcx>(mut place: Place<'tcx>) -> Place<'tcx> {
|
||||
/// - Deref of a box isn't captured in move clousres.
|
||||
fn restrict_capture_precision<'tcx>(
|
||||
capture_clause: hir::CaptureBy,
|
||||
mut place: Place<'tcx>,
|
||||
) -> Place<'tcx> {
|
||||
if place.projections.is_empty() {
|
||||
// Nothing to do here
|
||||
return place;
|
||||
|
|
@ -1693,7 +1733,8 @@ fn restrict_capture_precision<'tcx>(mut place: Place<'tcx>) -> Place<'tcx> {
|
|||
|
||||
place.projections.truncate(length);
|
||||
|
||||
place
|
||||
// Dont't capture projections on top of a box in move closures.
|
||||
restrict_precision_for_box(capture_clause, place)
|
||||
}
|
||||
|
||||
/// Truncates a place so that the resultant capture doesn't move data out of a reference
|
||||
|
|
|
|||
|
|
@ -114,8 +114,9 @@ fn struct_contains_ref_to_another_struct_3() {
|
|||
fn truncate_box_derefs() {
|
||||
struct S(i32);
|
||||
|
||||
let b = Box::new(S(10));
|
||||
|
||||
// Content within the box is moved within the closure
|
||||
let b = Box::new(S(10));
|
||||
let c = #[rustc_capture_analysis]
|
||||
//~^ ERROR: attributes on expressions are experimental
|
||||
//~| NOTE: see issue #15701 <https://github.com/rust-lang/rust/issues/15701>
|
||||
|
|
@ -129,6 +130,37 @@ fn truncate_box_derefs() {
|
|||
};
|
||||
|
||||
c();
|
||||
|
||||
// Content within the box is used by a shared ref and the box is the root variable
|
||||
let b = Box::new(S(10));
|
||||
|
||||
let c = #[rustc_capture_analysis]
|
||||
//~^ ERROR: attributes on expressions are experimental
|
||||
//~| NOTE: see issue #15701 <https://github.com/rust-lang/rust/issues/15701>
|
||||
move || {
|
||||
//~^ ERROR: First Pass analysis includes:
|
||||
//~| ERROR: Min Capture analysis includes:
|
||||
println!("{}", b.0);
|
||||
//~^ NOTE: Capturing b[Deref,(0, 0)] -> ByValue
|
||||
//~| NOTE: Min Capture b[] -> ByValue
|
||||
};
|
||||
|
||||
c();
|
||||
|
||||
// Content within the box is used by a shared ref and the box is not the root variable
|
||||
let b = Box::new(S(10));
|
||||
let t = (0, b);
|
||||
|
||||
let c = #[rustc_capture_analysis]
|
||||
//~^ ERROR: attributes on expressions are experimental
|
||||
//~| NOTE: see issue #15701 <https://github.com/rust-lang/rust/issues/15701>
|
||||
move || {
|
||||
//~^ ERROR: First Pass analysis includes:
|
||||
//~| ERROR: Min Capture analysis includes:
|
||||
println!("{}", t.1.0);
|
||||
//~^ NOTE: Capturing t[(1, 0),Deref,(0, 0)] -> ByValue
|
||||
//~| NOTE: Min Capture t[(1, 0)] -> ByValue
|
||||
};
|
||||
}
|
||||
|
||||
fn main() {
|
||||
|
|
|
|||
|
|
@ -44,7 +44,25 @@ LL | let mut c = #[rustc_capture_analysis]
|
|||
= help: add `#![feature(stmt_expr_attributes)]` to the crate attributes to enable
|
||||
|
||||
error[E0658]: attributes on expressions are experimental
|
||||
--> $DIR/move_closure.rs:119:13
|
||||
--> $DIR/move_closure.rs:120:13
|
||||
|
|
||||
LL | let c = #[rustc_capture_analysis]
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
|
||||
= note: see issue #15701 <https://github.com/rust-lang/rust/issues/15701> for more information
|
||||
= help: add `#![feature(stmt_expr_attributes)]` to the crate attributes to enable
|
||||
|
||||
error[E0658]: attributes on expressions are experimental
|
||||
--> $DIR/move_closure.rs:137:13
|
||||
|
|
||||
LL | let c = #[rustc_capture_analysis]
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
|
||||
= note: see issue #15701 <https://github.com/rust-lang/rust/issues/15701> for more information
|
||||
= help: add `#![feature(stmt_expr_attributes)]` to the crate attributes to enable
|
||||
|
||||
error[E0658]: attributes on expressions are experimental
|
||||
--> $DIR/move_closure.rs:154:13
|
||||
|
|
||||
LL | let c = #[rustc_capture_analysis]
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
|
@ -247,7 +265,7 @@ LL | let _t = t.0.0;
|
|||
| ^^^^^
|
||||
|
||||
error: First Pass analysis includes:
|
||||
--> $DIR/move_closure.rs:122:5
|
||||
--> $DIR/move_closure.rs:123:5
|
||||
|
|
||||
LL | / move || {
|
||||
LL | |
|
||||
|
|
@ -259,18 +277,18 @@ LL | | };
|
|||
| |_____^
|
||||
|
|
||||
note: Capturing b[Deref,(0, 0)] -> ByValue
|
||||
--> $DIR/move_closure.rs:125:18
|
||||
--> $DIR/move_closure.rs:126:18
|
||||
|
|
||||
LL | let _t = b.0;
|
||||
| ^^^
|
||||
note: Capturing b[] -> ByValue
|
||||
--> $DIR/move_closure.rs:125:18
|
||||
--> $DIR/move_closure.rs:126:18
|
||||
|
|
||||
LL | let _t = b.0;
|
||||
| ^^^
|
||||
|
||||
error: Min Capture analysis includes:
|
||||
--> $DIR/move_closure.rs:122:5
|
||||
--> $DIR/move_closure.rs:123:5
|
||||
|
|
||||
LL | / move || {
|
||||
LL | |
|
||||
|
|
@ -282,11 +300,83 @@ LL | | };
|
|||
| |_____^
|
||||
|
|
||||
note: Min Capture b[] -> ByValue
|
||||
--> $DIR/move_closure.rs:125:18
|
||||
--> $DIR/move_closure.rs:126:18
|
||||
|
|
||||
LL | let _t = b.0;
|
||||
| ^^^
|
||||
|
||||
error: aborting due to 18 previous errors; 1 warning emitted
|
||||
error: First Pass analysis includes:
|
||||
--> $DIR/move_closure.rs:140:5
|
||||
|
|
||||
LL | / move || {
|
||||
LL | |
|
||||
LL | |
|
||||
LL | | println!("{}", b.0);
|
||||
LL | |
|
||||
LL | |
|
||||
LL | | };
|
||||
| |_____^
|
||||
|
|
||||
note: Capturing b[Deref,(0, 0)] -> ByValue
|
||||
--> $DIR/move_closure.rs:143:24
|
||||
|
|
||||
LL | println!("{}", b.0);
|
||||
| ^^^
|
||||
|
||||
error: Min Capture analysis includes:
|
||||
--> $DIR/move_closure.rs:140:5
|
||||
|
|
||||
LL | / move || {
|
||||
LL | |
|
||||
LL | |
|
||||
LL | | println!("{}", b.0);
|
||||
LL | |
|
||||
LL | |
|
||||
LL | | };
|
||||
| |_____^
|
||||
|
|
||||
note: Min Capture b[] -> ByValue
|
||||
--> $DIR/move_closure.rs:143:24
|
||||
|
|
||||
LL | println!("{}", b.0);
|
||||
| ^^^
|
||||
|
||||
error: First Pass analysis includes:
|
||||
--> $DIR/move_closure.rs:157:5
|
||||
|
|
||||
LL | / move || {
|
||||
LL | |
|
||||
LL | |
|
||||
LL | | println!("{}", t.1.0);
|
||||
LL | |
|
||||
LL | |
|
||||
LL | | };
|
||||
| |_____^
|
||||
|
|
||||
note: Capturing t[(1, 0),Deref,(0, 0)] -> ByValue
|
||||
--> $DIR/move_closure.rs:160:24
|
||||
|
|
||||
LL | println!("{}", t.1.0);
|
||||
| ^^^^^
|
||||
|
||||
error: Min Capture analysis includes:
|
||||
--> $DIR/move_closure.rs:157:5
|
||||
|
|
||||
LL | / move || {
|
||||
LL | |
|
||||
LL | |
|
||||
LL | | println!("{}", t.1.0);
|
||||
LL | |
|
||||
LL | |
|
||||
LL | | };
|
||||
| |_____^
|
||||
|
|
||||
note: Min Capture t[(1, 0)] -> ByValue
|
||||
--> $DIR/move_closure.rs:160:24
|
||||
|
|
||||
LL | println!("{}", t.1.0);
|
||||
| ^^^^^
|
||||
|
||||
error: aborting due to 24 previous errors; 1 warning emitted
|
||||
|
||||
For more information about this error, try `rustc --explain E0658`.
|
||||
|
|
|
|||
Loading…
Add table
Reference in a new issue