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Only borrow place for matching under specific conditions

This commit is contained in:
Roxane 2021-02-23 23:39:33 -05:00
parent 685a4c6b6b
commit 74fc64303f
11 changed files with 193 additions and 49 deletions
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2
compiler/rustc_mir_build/src/build/expr/as_place.rs
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@ -100,7 +100,7 @@ fn convert_to_hir_projections_and_truncate_for_capture<'tcx>(
// single and multiple variants.
// For single variants, enums are not captured completely.
// We keep track of VariantIdx so we can use this information
// if the next ProjectionElem is a Field
// if the next ProjectionElem is a Field.
variant = Some(*idx);
continue;
}

2
compiler/rustc_mir_build/src/build/expr/into.rs
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@ -420,6 +420,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
| ExprKind::PlaceTypeAscription { .. }
| ExprKind::ValueTypeAscription { .. } => {
debug_assert!(Category::of(&expr.kind) == Some(Category::Place));
let place = unpack!(block = this.as_place(block, expr));
let rvalue = Rvalue::Use(this.consume_by_copy_or_move(place));
this.cfg.push_assign(block, source_info, destination, rvalue);
@ -436,6 +437,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
}
debug_assert!(Category::of(&expr.kind) == Some(Category::Place));
let place = unpack!(block = this.as_place(block, expr));
let rvalue = Rvalue::Use(this.consume_by_copy_or_move(place));
this.cfg.push_assign(block, source_info, destination, rvalue);

9
compiler/rustc_mir_build/src/build/matches/simplify.rs
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@ -68,7 +68,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
let match_pairs = mem::take(&mut candidate.match_pairs);
if let [MatchPair { pattern: Pat { kind: box PatKind::Or { pats }, .. }, place }] =
&*match_pairs.clone()
&*match_pairs
{
existing_bindings.extend_from_slice(&new_bindings);
mem::swap(&mut candidate.bindings, &mut existing_bindings);
@ -155,12 +155,10 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
ascription: thir::pattern::Ascription { variance, user_ty, user_ty_span },
} => {
// Apply the type ascription to the value at `match_pair.place`, which is the
// value being matched, taking the variance field into account.
let place = match_pair.place.clone().into_place(self.tcx, self.typeck_results);
candidate.ascriptions.push(Ascription {
span: user_ty_span,
user_ty,
source: place,
source: match_pair.place.clone().into_place(self.tcx, self.typeck_results),
variance,
});
@ -175,12 +173,11 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
}
PatKind::Binding { name, mutability, mode, var, ty, ref subpattern, is_primary: _ } => {
let place = match_pair.place.clone().into_place(self.tcx, self.typeck_results);
candidate.bindings.push(Binding {
name,
mutability,
span: match_pair.pattern.span,
source: place,
source: match_pair.place.clone().into_place(self.tcx, self.typeck_results),
var_id: var,
var_ty: ty,
binding_mode: mode,

43
compiler/rustc_mir_build/src/thir/cx/expr.rs
View File

@ -455,32 +455,18 @@ impl<'thir, 'tcx> Cx<'thir, 'tcx> {
);
let fake_reads = match self.typeck_results().closure_fake_reads.get(&def_id) {
Some(vals) => {
Some(
vals.iter()
.map(|(place, cause)| {
(
self.arena.alloc(
self.convert_captured_hir_place(expr, place.clone()),
),
*cause,
)
// let var_hir_id = match val.base {
// HirPlaceBase::Upvar(upvar_id) => {
// debug!("upvar");
// upvar_id.var_path.hir_id
// }
// _ => {
// bug!(
// "Do not know how to get HirId out of Rvalue and StaticItem"
// );
// }
// };
// self.fake_read_capture_upvar(expr, val.clone(), var_hir_id)
})
.collect(),
)
}
Some(vals) => Some(
vals.iter()
.map(|(place, cause)| {
(
self.arena.alloc(
self.convert_captured_hir_place(expr, place.clone()),
),
*cause,
)
})
.collect(),
),
None => None,
};
@ -1058,6 +1044,11 @@ impl<'thir, 'tcx> Cx<'thir, 'tcx> {
let temp_lifetime = self.region_scope_tree.temporary_scope(closure_expr.hir_id.local_id);
let var_ty = place.base_ty;
// The result of capture analysis in `rustc_typeck/check/upvar.rs`represents a captured path
// as it's seen for use within the closure and not at the time of closure creation.
//
// That is we see expect to see it start from a captured upvar and not something that is local
// to the closure's parent.
let var_hir_id = match place.base {
HirPlaceBase::Upvar(upvar_id) => upvar_id.var_path.hir_id,
base => bug!("Expected an upvar, found {:?}", base),

38
compiler/rustc_typeck/src/expr_use_visitor.rs
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@ -8,10 +8,10 @@ pub use self::ConsumeMode::*;
pub use rustc_middle::hir::place::{Place, PlaceBase, PlaceWithHirId, Projection};
use rustc_hir as hir;
use rustc_hir::def::{DefKind, Res};
use rustc_hir::def::Res;
use rustc_hir::def_id::LocalDefId;
use rustc_hir::PatKind;
use rustc_hir::QPath;
//use rustc_hir::QPath;
use rustc_index::vec::Idx;
use rustc_infer::infer::InferCtxt;
use rustc_middle::hir::place::ProjectionKind;
@ -54,7 +54,6 @@ pub trait Delegate<'tcx> {
// `diag_expr_id` is the id used for diagnostics (see `consume` for more details).
fn mutate(&mut self, assignee_place: &PlaceWithHirId<'tcx>, diag_expr_id: hir::HirId);
// [FIXME] RFC2229 This should also affect clippy ref: https://github.com/sexxi-goose/rust/pull/27
fn fake_read(&mut self, place: Place<'tcx>, cause: FakeReadCause);
}
@ -235,24 +234,30 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
hir::ExprKind::Match(ref discr, arms, _) => {
let discr_place = return_if_err!(self.mc.cat_expr(&discr));
// Matching should not always be considered a use of the place, hence
// discr does not necessarily need to be borrowed.
// We only want to borrow discr if the pattern contain something other
// than wildcards
// than wildcards.
let ExprUseVisitor { ref mc, body_owner: _, delegate: _ } = *self;
let mut needs_to_be_read = false;
for arm in arms.iter() {
return_if_err!(mc.cat_pattern(discr_place.clone(), &arm.pat, |_place, pat| {
if let PatKind::Binding(_, _, _, opt_sub_pat) = pat.kind {
if let None = opt_sub_pat {
needs_to_be_read = true;
}
} else if let PatKind::TupleStruct(qpath, _, _) = &pat.kind {
// If a TupleStruct has a Some PathSegment, we should read the discr_place
// regardless if it contains a Wild pattern later
if let QPath::Resolved(_, path) = qpath {
if let Res::Def(DefKind::Ctor(_, _), _) = path.res {
match &pat.kind {
PatKind::Binding(_, _, _, opt_sub_pat) => {
// If the opt_sub_pat is None, than the binding does not count as
// a wildcard for the purpose of borrowing discr
if let None = opt_sub_pat {
needs_to_be_read = true;
}
}
PatKind::TupleStruct(_, _, _)
| PatKind::Struct(_, _, _)
| PatKind::Lit(_) => {
// If the PatKind is a TupleStruct, Struct, or Lit then we want
// to borrow discr
needs_to_be_read = true;
}
_ => {}
}
}));
}
@ -629,6 +634,8 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
/// - When reporting the Place back to the Delegate, ensure that the UpvarId uses the enclosing
/// closure as the DefId.
fn walk_captures(&mut self, closure_expr: &hir::Expr<'_>) {
debug!("walk_captures({:?})", closure_expr);
let closure_def_id = self.tcx().hir().local_def_id(closure_expr.hir_id).to_def_id();
let upvars = self.tcx().upvars_mentioned(self.body_owner);
@ -645,10 +652,9 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
if upvars.map_or(body_owner_is_closure, |upvars| {
!upvars.contains_key(&upvar_id.var_path.hir_id)
}) {
// [FIXME] RFC2229 Update this comment
// The nested closure might be capturing the current (enclosing) closure's local variables.
// The nested closure might be fake reading the current (enclosing) closure's local variables.
// We check if the root variable is ever mentioned within the enclosing closure, if not
// then for the current body (if it's a closure) these aren't captures, we will ignore them.
// then for the current body (if it's a closure) these do not require fake_read, we will ignore them.
continue;
}
}

24
src/test/ui/closures/2229_closure_analysis/run_pass/lit-pattern-matching-with-methods.rs Normal file
View File

@ -0,0 +1,24 @@
//check-pass
#![feature(capture_disjoint_fields)]
//~^ WARNING: the feature `capture_disjoint_fields` is incomplete
#![warn(unused)]
#![feature(rustc_attrs)]
#![feature(btree_drain_filter)]
use std::collections::BTreeMap;
use std::panic::{catch_unwind, AssertUnwindSafe};
fn main() {
let mut map = BTreeMap::new();
map.insert("a", ());
map.insert("b", ());
map.insert("c", ());
{
let mut it = map.drain_filter(|_, _| true);
catch_unwind(AssertUnwindSafe(|| while it.next().is_some() {})).unwrap_err();
let result = catch_unwind(AssertUnwindSafe(|| it.next()));
assert!(matches!(result, Ok(None)));
}
}

11
src/test/ui/closures/2229_closure_analysis/run_pass/lit-pattern-matching-with-methods.stderr Normal file
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@ -0,0 +1,11 @@
warning: the feature `capture_disjoint_fields` is incomplete and may not be safe to use and/or cause compiler crashes
--> $DIR/lit-pattern-matching-with-methods.rs:2:12
|
LL | #![feature(capture_disjoint_fields)]
| ^^^^^^^^^^^^^^^^^^^^^^^
|
= note: `#[warn(incomplete_features)]` on by default
= note: see issue #53488 <https://github.com/rust-lang/rust/issues/53488> for more information
warning: 1 warning emitted

48
src/test/ui/closures/2229_closure_analysis/run_pass/struct-pattern-matching-with-methods.rs Normal file
View File

@ -0,0 +1,48 @@
//check-pass
#![feature(capture_disjoint_fields)]
//~^ WARNING: the feature `capture_disjoint_fields` is incomplete
#![warn(unused)]
#![feature(rustc_attrs)]
#[derive(Debug, Clone, Copy)]
enum PointType {
TwoD { x: u32, y: u32 },
ThreeD{ x: u32, y: u32, z: u32 }
}
struct Points {
points: Vec<PointType>,
}
impl Points {
pub fn test1(&mut self) -> Vec<usize> {
(0..self.points.len())
.filter_map(|i| {
let idx = i as usize;
match self.test2(idx) {
PointType::TwoD { .. } => Some(i),
PointType::ThreeD { .. } => None,
}
})
.collect()
}
pub fn test2(&mut self, i: usize) -> PointType {
self.points[i]
}
}
fn main() {
let mut points = Points {
points: Vec::<PointType>::new()
};
points.points.push(PointType::ThreeD { x:0, y:0, z:0 });
points.points.push(PointType::TwoD{ x:0, y:0 });
points.points.push(PointType::ThreeD{ x:0, y:0, z:0 });
points.points.push(PointType::TwoD{ x:0, y:0 });
println!("{:?}", points.test1());
println!("{:?}", points.points);
}

11
src/test/ui/closures/2229_closure_analysis/run_pass/struct-pattern-matching-with-methods.stderr Normal file
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@ -0,0 +1,11 @@
warning: the feature `capture_disjoint_fields` is incomplete and may not be safe to use and/or cause compiler crashes
--> $DIR/struct-pattern-matching-with-methods.rs:2:12
|
LL | #![feature(capture_disjoint_fields)]
| ^^^^^^^^^^^^^^^^^^^^^^^
|
= note: `#[warn(incomplete_features)]` on by default
= note: see issue #53488 <https://github.com/rust-lang/rust/issues/53488> for more information
warning: 1 warning emitted

43
src/test/ui/closures/2229_closure_analysis/run_pass/tuple-struct-pattern-matching-with-methods.rs Normal file
View File

@ -0,0 +1,43 @@
//check-pass
#![feature(capture_disjoint_fields)]
//~^ WARNING: the feature `capture_disjoint_fields` is incomplete
#[derive(Copy, Clone)]
enum PointType {
TwoD(u32, u32),
ThreeD(u32, u32, u32)
}
struct Points {
points: Vec<PointType>,
}
impl Points {
pub fn test1(&mut self) -> Vec<usize> {
(0..self.points.len())
.filter_map(|i| {
match self.test2(i) {
PointType::TwoD (..) => Some(i),
PointType::ThreeD (..) => None,
}
})
.collect()
}
pub fn test2(&mut self, i: usize) -> PointType {
self.points[i]
}
}
fn main() {
let mut points = Points {
points: Vec::<PointType>::new()
};
points.points.push(PointType::ThreeD(0,0,0));
points.points.push(PointType::TwoD(0,0));
points.points.push(PointType::ThreeD(0,0,1));
points.points.push(PointType::TwoD(0,1));
println!("{:?}", points.test1());
}

11
src/test/ui/closures/2229_closure_analysis/run_pass/tuple-struct-pattern-matching-with-methods.stderr Normal file
View File

@ -0,0 +1,11 @@
warning: the feature `capture_disjoint_fields` is incomplete and may not be safe to use and/or cause compiler crashes
--> $DIR/tuple-struct-pattern-matching-with-methods.rs:2:12
|
LL | #![feature(capture_disjoint_fields)]
| ^^^^^^^^^^^^^^^^^^^^^^^
|
= note: `#[warn(incomplete_features)]` on by default
= note: see issue #53488 <https://github.com/rust-lang/rust/issues/53488> for more information
warning: 1 warning emitted