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Auto merge of #46268 - arielb1:union-borrow, r=nikomatsakis

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MIR borrowck: implement union-and-array-compatible semantics

Fixes #44831.
Fixes #44834.
Fixes #45537.
Fixes #45696 (by implementing DerefPure semantics, which is what we want going forward).

r? @nikomatsakis
This commit is contained in:
bors 2017-12-06 18:30:15 +00:00
commit cf30759a84
17 changed files with 608 additions and 176 deletions
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6
src/libcore/cell.rs
View File

@ -1084,9 +1084,11 @@ impl<'b, T: ?Sized> RefMut<'b, T> {
pub fn map<U: ?Sized, F>(orig: RefMut<'b, T>, f: F) -> RefMut<'b, U>
where F: FnOnce(&mut T) -> &mut U
{
// FIXME(nll-rfc#40): fix borrow-check
let RefMut { value, borrow } = orig;
RefMut {
value: f(orig.value),
borrow: orig.borrow,
value: f(value),
borrow: borrow,
}
}
}

18
src/libcore/iter/mod.rs
View File

@ -1776,12 +1776,18 @@ impl<I: Iterator> Iterator for Peekable<I> {
#[inline]
fn nth(&mut self, n: usize) -> Option<I::Item> {
match self.peeked.take() {
// the .take() below is just to avoid "move into pattern guard"
Some(ref mut v) if n == 0 => v.take(),
Some(None) => None,
Some(Some(_)) => self.iter.nth(n - 1),
None => self.iter.nth(n),
// FIXME(#6393): merge these when borrow-checking gets better.
if n == 0 {
match self.peeked.take() {
Some(v) => v,
None => self.iter.nth(n),
}
} else {
match self.peeked.take() {
Some(None) => None,
Some(Some(_)) => self.iter.nth(n - 1),
None => self.iter.nth(n),
}
}
}

513
src/librustc_mir/borrow_check/mod.rs
View File

@ -12,6 +12,7 @@
use rustc::hir;
use rustc::hir::def_id::DefId;
use rustc::hir::map::definitions::DefPathData;
use rustc::infer::InferCtxt;
use rustc::ty::{self, ParamEnv, TyCtxt};
use rustc::ty::maps::Providers;
@ -36,6 +37,9 @@ use dataflow::move_paths::{IllegalMoveOriginKind, MoveError};
use dataflow::move_paths::{HasMoveData, LookupResult, MoveData, MoveOutIndex, MovePathIndex};
use util::borrowck_errors::{BorrowckErrors, Origin};
use std::fmt;
use std::iter;
use self::MutateMode::{JustWrite, WriteAndRead};
pub(crate) mod nll;
@ -128,6 +132,12 @@ fn do_mir_borrowck<'a, 'gcx, 'tcx>(
move_data: move_data,
param_env: param_env,
};
let body_id = match tcx.def_key(def_id).disambiguated_data.data {
DefPathData::StructCtor |
DefPathData::EnumVariant(_) => None,
_ => Some(tcx.hir.body_owned_by(id))
};
let dead_unwinds = IdxSetBuf::new_empty(mir.basic_blocks().len());
let mut flow_inits = FlowInProgress::new(do_dataflow(
tcx,
@ -189,6 +199,11 @@ fn do_mir_borrowck<'a, 'gcx, 'tcx>(
node_id: id,
move_data: &mdpe.move_data,
param_env: param_env,
locals_are_invalidated_at_exit: match tcx.hir.body_owner_kind(id) {
hir::BodyOwnerKind::Const |
hir::BodyOwnerKind::Static(_) => false,
hir::BodyOwnerKind::Fn => true,
},
storage_dead_or_drop_error_reported: FxHashSet(),
};
@ -198,7 +213,7 @@ fn do_mir_borrowck<'a, 'gcx, 'tcx>(
id,
&attributes,
&dead_unwinds,
Borrows::new(tcx, mir, opt_regioncx),
Borrows::new(tcx, mir, opt_regioncx, def_id, body_id),
|bd, i| bd.location(i),
));
@ -220,6 +235,13 @@ pub struct MirBorrowckCtxt<'cx, 'gcx: 'tcx, 'tcx: 'cx> {
node_id: ast::NodeId,
move_data: &'cx MoveData<'tcx>,
param_env: ParamEnv<'gcx>,
/// This keeps track of whether local variables are free-ed when the function
/// exits even without a `StorageDead`, which appears to be the case for
/// constants.
///
/// I'm not sure this is the right approach - @eddyb could you try and
/// figure this out?
locals_are_invalidated_at_exit: bool,
/// This field keeps track of when storage dead or drop errors are reported
/// in order to stop duplicate error reporting and identify the conditions required
/// for a "temporary value dropped here while still borrowed" error. See #45360.
@ -306,8 +328,7 @@ impl<'cx, 'gcx, 'tcx> DataflowResultsConsumer<'cx, 'tcx> for MirBorrowckCtxt<'cx
}
fn visit_block_entry(&mut self, bb: BasicBlock, flow_state: &Self::FlowState) {
let summary = flow_state.summary();
debug!("MirBorrowckCtxt::process_block({:?}): {}", bb, summary);
debug!("MirBorrowckCtxt::process_block({:?}): {}", bb, flow_state);
}
fn visit_statement_entry(
@ -316,12 +337,11 @@ impl<'cx, 'gcx, 'tcx> DataflowResultsConsumer<'cx, 'tcx> for MirBorrowckCtxt<'cx
stmt: &Statement<'tcx>,
flow_state: &Self::FlowState,
) {
let summary = flow_state.summary();
debug!(
"MirBorrowckCtxt::process_statement({:?}, {:?}): {}",
location,
stmt,
summary
flow_state
);
let span = stmt.source_info.span;
match stmt.kind {
@ -423,12 +443,11 @@ impl<'cx, 'gcx, 'tcx> DataflowResultsConsumer<'cx, 'tcx> for MirBorrowckCtxt<'cx
flow_state: &Self::FlowState,
) {
let loc = location;
let summary = flow_state.summary();
debug!(
"MirBorrowckCtxt::process_terminator({:?}, {:?}): {}",
location,
term,
summary
flow_state
);
let span = term.source_info.span;
match term.kind {
@ -540,14 +559,13 @@ impl<'cx, 'gcx, 'tcx> DataflowResultsConsumer<'cx, 'tcx> for MirBorrowckCtxt<'cx
if self.place_is_invalidated_at_exit(&borrow.place) {
debug!("borrow conflicts at exit {:?}", borrow);
let borrow_span = self.mir.source_info(borrow.location).span;
// FIXME: should be talking about the region lifetime instead
// of just a span here.
let end_span = domain.opt_region_end_span(&borrow.region);
self.report_borrowed_value_does_not_live_long_enough(
ContextKind::StorageDead.new(loc),
(&borrow.place, borrow_span),
(&borrow.place, end_span.unwrap_or(span)),
end_span,
)
}
@ -641,8 +659,9 @@ enum WriteKind {
/// - Take flow state into consideration in `is_assignable()` for local variables
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
enum LocalMutationIsAllowed {
Move,
Yes,
No,
No
}
#[derive(Copy, Clone)]
@ -710,7 +729,7 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
context,
(sd, place_span.0),
flow_state,
|this, _index, borrow, common_prefix| match (rw, borrow.kind) {
|this, _index, borrow| match (rw, borrow.kind) {
(Read(_), BorrowKind::Shared) => Control::Continue,
(Read(kind), BorrowKind::Unique) | (Read(kind), BorrowKind::Mut) => {
match kind {
@ -727,7 +746,6 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
error_reported = true;
this.report_conflicting_borrow(
context,
common_prefix,
place_span,
bk,
&borrow,
@ -748,7 +766,6 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
error_reported = true;
this.report_conflicting_borrow(
context,
common_prefix,
place_span,
bk,
&borrow,
@ -934,7 +951,7 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
context,
(place, span),
(Deep, Write(WriteKind::Move)),
LocalMutationIsAllowed::Yes,
LocalMutationIsAllowed::Move,
flow_state,
);
@ -952,14 +969,16 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
/// Returns whether a borrow of this place is invalidated when the function
/// exits
fn place_is_invalidated_at_exit(&self, place: &Place<'tcx>) -> bool {
fn place_is_invalidated_at_exit(&mut self, place: &Place<'tcx>) -> bool {
debug!("place_is_invalidated_at_exit({:?})", place);
let root_place = self.prefixes(place, PrefixSet::All).last().unwrap();
// FIXME(nll-rfc#40): do more precise destructor tracking here. For now
// we just know that all locals are dropped at function exit (otherwise
// we'll have a memory leak) and assume that all statics have a destructor.
let (might_be_alive, will_be_dropped) = match root_place {
//
// FIXME: allow thread-locals to borrow other thread locals?
let (might_be_alive, will_be_dropped, local) = match root_place {
Place::Static(statik) => {
// Thread-locals might be dropped after the function exits, but
// "true" statics will never be.
@ -968,12 +987,12 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
.iter()
.any(|attr| attr.check_name("thread_local"));
(true, is_thread_local)
(true, is_thread_local, None)
}
Place::Local(_) => {
Place::Local(local) => {
// Locals are always dropped at function exit, and if they
// have a destructor it would've been called already.
(false, true)
(false, self.locals_are_invalidated_at_exit, Some(*local))
}
Place::Projection(..) => {
bug!("root of {:?} is a projection ({:?})?", place, root_place)
@ -996,8 +1015,19 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
PrefixSet::Shallow
};
self.prefixes(place, prefix_set)
.any(|prefix| prefix == root_place)
let result =
self.prefixes(place, prefix_set).any(|prefix| prefix == root_place);
if result {
if let Some(local) = local {
if let Some(_) = self.storage_dead_or_drop_error_reported.replace(local) {
debug!("place_is_invalidated_at_exit({:?}) - suppressed", place);
return false;
}
}
}
result
}
}
@ -1343,7 +1373,8 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
let local = &self.mir.local_decls[local];
match local.mutability {
Mutability::Not => match is_local_mutation_allowed {
LocalMutationIsAllowed::Yes => Ok(()),
LocalMutationIsAllowed::Yes |
LocalMutationIsAllowed::Move => Ok(()),
LocalMutationIsAllowed::No => Err(place),
},
Mutability::Mut => Ok(()),
@ -1368,10 +1399,14 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
// Mutably borrowed data is mutable, but only if we have a
// unique path to the `&mut`
hir::MutMutable => {
if self.is_upvar_field_projection(&proj.base).is_some() {
self.is_mutable(&proj.base, is_local_mutation_allowed)
} else {
self.is_unique(&proj.base)
match self.is_upvar_field_projection(&proj.base) {
Some(field) if {
self.mir.upvar_decls[field.index()].by_ref
} => {
self.is_mutable(&proj.base,
is_local_mutation_allowed)
}
_ => self.is_unique(&proj.base)
}
}
}
@ -1387,7 +1422,7 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
}
// `Box<T>` owns its content, so mutable if its location is mutable
_ if base_ty.is_box() => {
self.is_mutable(&proj.base, LocalMutationIsAllowed::No)
self.is_mutable(&proj.base, is_local_mutation_allowed)
}
// Deref should only be for reference, pointers or boxes
_ => bug!("Deref of unexpected type: {:?}", base_ty),
@ -1404,14 +1439,17 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
if let Some(field) = field_projection {
let decl = &self.mir.upvar_decls[field.index()];
return match decl.mutability {
Mutability::Mut => self.is_unique(&proj.base),
Mutability::Not => Err(place),
debug!("decl.mutability={:?} local_mutation_is_allowed={:?} place={:?}",
decl, is_local_mutation_allowed, place);
return match (decl.mutability, is_local_mutation_allowed) {
(Mutability::Not, LocalMutationIsAllowed::No) |
(Mutability::Not, LocalMutationIsAllowed::Yes) => Err(place),
(Mutability::Not, LocalMutationIsAllowed::Move) |
(Mutability::Mut, _) => self.is_unique(&proj.base),
};
}
self.is_mutable(&proj.base, LocalMutationIsAllowed::No)
self.is_mutable(&proj.base, is_local_mutation_allowed)
}
}
}
@ -1425,9 +1463,12 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
// Local variables are unique
Ok(())
}
Place::Static(..) => {
// Static variables are not
Err(place)
Place::Static(ref static_) => {
if !self.tcx.is_static_mut(static_.def_id) {
Err(place)
} else {
Ok(())
}
}
Place::Projection(ref proj) => {
match proj.elem {
@ -1478,7 +1519,350 @@ enum NoMovePathFound {
ReachedStatic,
}
/// The degree of overlap between 2 places for borrow-checking.
enum Overlap {
/// The places might partially overlap - in this case, we give
/// up and say that they might conflict. This occurs when
/// different fields of a union are borrowed. For example,
/// if `u` is a union, we have no way of telling how disjoint
/// `u.a.x` and `a.b.y` are.
Arbitrary,
/// The places have the same type, and are either completely disjoint
/// or equal - i.e. they can't "partially" overlap as can occur with
/// unions. This is the "base case" on which we recur for extensions
/// of the place.
EqualOrDisjoint,
/// The places are disjoint, so we know all extensions of them
/// will also be disjoint.
Disjoint,
}
impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
// Given that the bases of `elem1` and `elem2` are always either equal
// or disjoint (and have the same type!), return the overlap situation
// between `elem1` and `elem2`.
fn place_element_conflict(&self,
elem1: &Place<'tcx>,
elem2: &Place<'tcx>)
-> Overlap
{
match (elem1, elem2) {
(Place::Local(l1), Place::Local(l2)) => {
if l1 == l2 {
// the same local - base case, equal
debug!("place_element_conflict: DISJOINT-OR-EQ-LOCAL");
Overlap::EqualOrDisjoint
} else {
// different locals - base case, disjoint
debug!("place_element_conflict: DISJOINT-LOCAL");
Overlap::Disjoint
}
}
(Place::Static(..), Place::Static(..)) => {
// Borrows of statics do not have to be tracked here.
debug!("place_element_conflict: IGNORED-STATIC");
Overlap::Disjoint
}
(Place::Local(_), Place::Static(_)) |
(Place::Static(_), Place::Local(_)) => {
debug!("place_element_conflict: DISJOINT-STATIC-LOCAL");
Overlap::Disjoint
}
(Place::Projection(pi1), Place::Projection(pi2)) => {
match (&pi1.elem, &pi2.elem) {
(ProjectionElem::Deref, ProjectionElem::Deref) => {
// derefs (e.g. `*x` vs. `*x`) - recur.
debug!("place_element_conflict: DISJOINT-OR-EQ-DEREF");
Overlap::EqualOrDisjoint
}
(ProjectionElem::Field(f1, _), ProjectionElem::Field(f2, _)) => {
if f1 == f2 {
// same field (e.g. `a.y` vs. `a.y`) - recur.
debug!("place_element_conflict: DISJOINT-OR-EQ-FIELD");
Overlap::EqualOrDisjoint
} else {
let ty = pi1.base.ty(self.mir, self.tcx).to_ty(self.tcx);
match ty.sty {
ty::TyAdt(def, _) if def.is_union() => {
// Different fields of a union, we are basically stuck.
debug!("place_element_conflict: STUCK-UNION");
Overlap::Arbitrary
}
_ => {
// Different fields of a struct (`a.x` vs. `a.y`). Disjoint!
debug!("place_element_conflict: DISJOINT-FIELD");
Overlap::Disjoint
}
}
}
}
(ProjectionElem::Downcast(_, v1), ProjectionElem::Downcast(_, v2)) => {
// different variants are treated as having disjoint fields,
// even if they occupy the same "space", because it's
// impossible for 2 variants of the same enum to exist
// (and therefore, to be borrowed) at the same time.
//
// Note that this is different from unions - we *do* allow
// this code to compile:
//
// ```
// fn foo(x: &mut Result<i32, i32>) {
// let mut v = None;
// if let Ok(ref mut a) = *x {
// v = Some(a);
// }
// // here, you would *think* that the
// // *entirety* of `x` would be borrowed,
// // but in fact only the `Ok` variant is,
// // so the `Err` variant is *entirely free*:
// if let Err(ref mut a) = *x {
// v = Some(a);
// }
// drop(v);
// }
// ```
if v1 == v2 {
debug!("place_element_conflict: DISJOINT-OR-EQ-FIELD");
Overlap::EqualOrDisjoint
} else {
debug!("place_element_conflict: DISJOINT-FIELD");
Overlap::Disjoint
}
}
(ProjectionElem::Index(..), ProjectionElem::Index(..)) |
(ProjectionElem::Index(..), ProjectionElem::ConstantIndex { .. }) |
(ProjectionElem::Index(..), ProjectionElem::Subslice { .. }) |
(ProjectionElem::ConstantIndex { .. }, ProjectionElem::Index(..)) |
(ProjectionElem::ConstantIndex { .. }, ProjectionElem::ConstantIndex { .. }) |
(ProjectionElem::ConstantIndex { .. }, ProjectionElem::Subslice { .. }) |
(ProjectionElem::Subslice { .. }, ProjectionElem::Index(..)) |
(ProjectionElem::Subslice { .. }, ProjectionElem::ConstantIndex { .. }) |
(ProjectionElem::Subslice { .. }, ProjectionElem::Subslice { .. }) => {
// Array indexes (`a[0]` vs. `a[i]`). These can either be disjoint
// (if the indexes differ) or equal (if they are the same), so this
// is the recursive case that gives "equal *or* disjoint" its meaning.
//
// Note that by construction, MIR at borrowck can't subdivide
// `Subslice` accesses (e.g. `a[2..3][i]` will never be present) - they
// are only present in slice patterns, and we "merge together" nested
// slice patterns. That means we don't have to think about these. It's
// probably a good idea to assert this somewhere, but I'm too lazy.
//
// FIXME(#8636) we might want to return Disjoint if
// both projections are constant and disjoint.
debug!("place_element_conflict: DISJOINT-OR-EQ-ARRAY");
Overlap::EqualOrDisjoint
}
(ProjectionElem::Deref, _) |
(ProjectionElem::Field(..), _) |
(ProjectionElem::Index(..), _) |
(ProjectionElem::ConstantIndex { .. }, _) |
(ProjectionElem::Subslice { .. }, _) |
(ProjectionElem::Downcast(..), _) => {
bug!("mismatched projections in place_element_conflict: {:?} and {:?}",
elem1, elem2)
}
}
}
(Place::Projection(_), _) |
(_, Place::Projection(_)) => {
bug!("unexpected elements in place_element_conflict: {:?} and {:?}",
elem1, elem2)
}
}
}
fn borrow_conflicts_with_place(&mut self,
borrow: &BorrowData<'tcx>,
place: &Place<'tcx>,
access: ShallowOrDeep)
-> bool
{
debug!("borrow_conflicts_with_place({:?},{:?},{:?})", borrow, place, access);
// Return all the prefixes of `place` in reverse order, including
// downcasts.
fn place_elements<'a, 'tcx>(place: &'a Place<'tcx>) -> Vec<&'a Place<'tcx>>
{
let mut result = vec![];
let mut place = place;
loop {
result.push(place);
match place {
Place::Projection(interior) => {
place = &interior.base;
}
Place::Local(_) | Place::Static(_) => {
result.reverse();
return result;
}
}
}
}
let borrow_components = place_elements(&borrow.place);
let access_components = place_elements(place);
debug!("borrow_conflicts_with_place: components {:?} / {:?}",
borrow_components, access_components);
let borrow_components = borrow_components.into_iter()
.map(Some).chain(iter::repeat(None));
let access_components = access_components.into_iter()
.map(Some).chain(iter::repeat(None));
// The borrowck rules for proving disjointness are applied from the "root" of the
// borrow forwards, iterating over "similar" projections in lockstep until
// we can prove overlap one way or another. Essentially, we treat `Overlap` as
// a monoid and report a conflict if the product ends up not being `Disjoint`.
//
// At each step, if we didn't run out of borrow or place, we know that our elements
// have the same type, and that they only overlap if they are the identical.
//
// For example, if we are comparing these:
// BORROW: (*x1[2].y).z.a
// ACCESS: (*x1[i].y).w.b
//
// Then our steps are:
// x1 | x1 -- places are the same
// x1[2] | x1[i] -- equal or disjoint (disjoint if indexes differ)
// x1[2].y | x1[i].y -- equal or disjoint
// *x1[2].y | *x1[i].y -- equal or disjoint
// (*x1[2].y).z | (*x1[i].y).w -- we are disjoint and don't need to check more!
//
// Because `zip` does potentially bad things to the iterator inside, this loop
// also handles the case where the access might be a *prefix* of the borrow, e.g.
//
// BORROW: (*x1[2].y).z.a
// ACCESS: x1[i].y
//
// Then our steps are:
// x1 | x1 -- places are the same
// x1[2] | x1[i] -- equal or disjoint (disjoint if indexes differ)
// x1[2].y | x1[i].y -- equal or disjoint
//
// -- here we run out of access - the borrow can access a part of it. If this
// is a full deep access, then we *know* the borrow conflicts with it. However,
// if the access is shallow, then we can proceed:
//
// x1[2].y | (*x1[i].y) -- a deref! the access can't get past this, so we
// are disjoint
//
// Our invariant is, that at each step of the iteration:
// - If we didn't run out of access to match, our borrow and access are comparable
// and either equal or disjoint.
// - If we did run out of accesss, the borrow can access a part of it.
for (borrow_c, access_c) in borrow_components.zip(access_components) {
// loop invariant: borrow_c is always either equal to access_c or disjoint from it.
debug!("borrow_conflicts_with_place: {:?} vs. {:?}", borrow_c, access_c);
match (borrow_c, access_c) {
(None, _) => {
// If we didn't run out of access, the borrow can access all of our
// place (e.g. a borrow of `a.b` with an access to `a.b.c`),
// so we have a conflict.
//
// If we did, then we still know that the borrow can access a *part*
// of our place that our access cares about (a borrow of `a.b.c`
// with an access to `a.b`), so we still have a conflict.
//
// FIXME: Differs from AST-borrowck; includes drive-by fix
// to #38899. Will probably need back-compat mode flag.
debug!("borrow_conflict_with_place: full borrow, CONFLICT");
return true;
}
(Some(borrow_c), None) => {
// We know that the borrow can access a part of our place. This
// is a conflict if that is a part our access cares about.
let (base, elem) = match borrow_c {
Place::Projection(box Projection { base, elem }) => (base, elem),
_ => bug!("place has no base?")
};
let base_ty = base.ty(self.mir, self.tcx).to_ty(self.tcx);
match (elem, &base_ty.sty, access) {
(_, _, Shallow(Some(ArtificialField::Discriminant))) |
(_, _, Shallow(Some(ArtificialField::ArrayLength))) => {
// The discriminant and array length are like
// additional fields on the type; they do not
// overlap any existing data there. Furthermore,
// they cannot actually be a prefix of any
// borrowed place (at least in MIR as it is
// currently.)
//
// e.g. a (mutable) borrow of `a[5]` while we read the
// array length of `a`.
debug!("borrow_conflicts_with_place: implicit field");
return false;
}
(ProjectionElem::Deref, _, Shallow(None)) => {
// e.g. a borrow of `*x.y` while we shallowly access `x.y` or some
// prefix thereof - the shallow access can't touch anything behind
// the pointer.
debug!("borrow_conflicts_with_place: shallow access behind ptr");
return false;
}
(ProjectionElem::Deref, ty::TyRef(_, ty::TypeAndMut {
ty: _, mutbl: hir::MutImmutable
}), _) => {
// the borrow goes through a dereference of a shared reference.
//
// I'm not sure why we are tracking these borrows - shared
// references can *always* be aliased, which means the
// permission check already account for this borrow.
debug!("borrow_conflicts_with_place: behind a shared ref");
return false;
}
(ProjectionElem::Deref, _, Deep) |
(ProjectionElem::Field { .. }, _, _) |
(ProjectionElem::Index { ..}, _, _) |
(ProjectionElem::ConstantIndex { .. }, _, _) |
(ProjectionElem::Subslice { .. }, _, _) |
(ProjectionElem::Downcast { .. }, _, _) => {
// Recursive case. This can still be disjoint on a
// further iteration if this a shallow access and
// there's a deref later on, e.g. a borrow
// of `*x.y` while accessing `x`.
}
}
}
(Some(borrow_c), Some(access_c)) => {
match self.place_element_conflict(&borrow_c, access_c) {
Overlap::Arbitrary => {
// We have encountered different fields of potentially
// the same union - the borrow now partially overlaps.
//
// There is no *easy* way of comparing the fields
// further on, because they might have different types
// (e.g. borrows of `u.a.0` and `u.b.y` where `.0` and
// `.y` come from different structs).
//
// We could try to do some things here - e.g. count
// dereferences - but that's probably not a good
// idea, at least for now, so just give up and
// report a conflict. This is unsafe code anyway so
// the user could always use raw pointers.
debug!("borrow_conflicts_with_place: arbitrary -> conflict");
return true;
}
Overlap::EqualOrDisjoint => {
// This is the recursive case - proceed to the next element.
}
Overlap::Disjoint => {
// We have proven the borrow disjoint - further
// projections will remain disjoint.
debug!("borrow_conflicts_with_place: disjoint");
return false;
}
}
}
}
}
unreachable!("iter::repeat returned None")
}
fn each_borrow_involving_path<F>(
&mut self,
_context: Context,
@ -1486,7 +1870,7 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
flow_state: &InProgress<'cx, 'gcx, 'tcx>,
mut op: F,
) where
F: FnMut(&mut Self, BorrowIndex, &BorrowData<'tcx>, &Place<'tcx>) -> Control,
F: FnMut(&mut Self, BorrowIndex, &BorrowData<'tcx>) -> Control,
{
let (access, place) = access_place;
@ -1501,47 +1885,9 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
'next_borrow: for i in flow_state.borrows.elems_incoming() {
let borrowed = &data[i];
// Is `place` (or a prefix of it) already borrowed? If
// so, that's relevant.
//
// FIXME: Differs from AST-borrowck; includes drive-by fix
// to #38899. Will probably need back-compat mode flag.
for accessed_prefix in self.prefixes(place, PrefixSet::All) {
if *accessed_prefix == borrowed.place {
// FIXME: pass in enum describing case we are in?
let ctrl = op(self, i, borrowed, accessed_prefix);
if ctrl == Control::Break {
return;
}
}
}
// Is `place` a prefix (modulo access type) of the
// `borrowed.place`? If so, that's relevant.
let prefix_kind = match access {
Shallow(Some(ArtificialField::Discriminant)) |
Shallow(Some(ArtificialField::ArrayLength)) => {
// The discriminant and array length are like
// additional fields on the type; they do not
// overlap any existing data there. Furthermore,
// they cannot actually be a prefix of any
// borrowed place (at least in MIR as it is
// currently.)
continue 'next_borrow;
}
Shallow(None) => PrefixSet::Shallow,
Deep => PrefixSet::Supporting,
};
for borrowed_prefix in self.prefixes(&borrowed.place, prefix_kind) {
if borrowed_prefix == place {
// FIXME: pass in enum describing case we are in?
let ctrl = op(self, i, borrowed, borrowed_prefix);
if ctrl == Control::Break {
return;
}
}
if self.borrow_conflicts_with_place(borrowed, place, access) {
let ctrl = op(self, i, borrowed);
if ctrl == Control::Break { return; }
}
}
}
@ -1595,6 +1941,7 @@ mod prefixes {
}
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
#[allow(dead_code)]
pub(super) enum PrefixSet {
/// Doesn't stop until it returns the base case (a Local or
/// Static prefix).
@ -1907,17 +2254,11 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
fn report_conflicting_borrow(
&mut self,
context: Context,
common_prefix: &Place<'tcx>,
(place, span): (&Place<'tcx>, Span),
gen_borrow_kind: BorrowKind,
issued_borrow: &BorrowData,
end_issued_loan_span: Option<Span>,
) {
use self::prefixes::IsPrefixOf;
assert!(common_prefix.is_prefix_of(place));
assert!(common_prefix.is_prefix_of(&issued_borrow.place));
let issued_span = self.retrieve_borrow_span(issued_borrow);
let new_closure_span = self.find_closure_span(span, context.loc);
@ -2373,8 +2714,10 @@ impl<'b, 'gcx, 'tcx> InProgress<'b, 'gcx, 'tcx> {
xform_move_outs(&mut self.move_outs);
xform_ever_inits(&mut self.ever_inits);
}
}
fn summary(&self) -> String {
impl<'b, 'gcx, 'tcx> fmt::Display for InProgress<'b, 'gcx, 'tcx> {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
let mut s = String::new();
s.push_str("borrows in effect: [");
@ -2451,7 +2794,7 @@ impl<'b, 'gcx, 'tcx> InProgress<'b, 'gcx, 'tcx> {
});
s.push_str("]");
return s;
fmt::Display::fmt(&s, fmt)
}
}

11
src/librustc_mir/build/cfg.rs
View File

@ -51,6 +51,17 @@ impl<'tcx> CFG<'tcx> {
source_info: SourceInfo,
region_scope: region::Scope) {
if tcx.sess.emit_end_regions() {
if let region::ScopeData::CallSite(_) = region_scope.data() {
// The CallSite scope (aka the root scope) is sort of weird, in that it is
// supposed to "separate" the "interior" and "exterior" of a closure. Being
// that, it is not really a part of the region hierarchy, but for some
// reason it *is* considered a part of it.
//
// It should die a hopefully painful death with NLL, so let's leave this hack
// for now so that nobody can complain about soundness.
return
}
self.push(block, Statement {
source_info,
kind: StatementKind::EndRegion(region_scope),

60
src/librustc_mir/dataflow/impls/borrows.rs
View File

@ -8,6 +8,9 @@
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use rustc::hir;
use rustc::hir::def_id::DefId;
use rustc::middle::region;
use rustc::mir::{self, Location, Mir};
use rustc::mir::visit::Visitor;
use rustc::ty::{self, Region, TyCtxt};
@ -27,6 +30,7 @@ use borrow_check::nll::ToRegionVid;
use syntax_pos::Span;
use std::fmt;
use std::rc::Rc;
// `Borrows` maps each dataflow bit to an `Rvalue::Ref`, which can be
// uniquely identified in the MIR by the `Location` of the assigment
@ -34,9 +38,12 @@ use std::fmt;
pub struct Borrows<'a, 'gcx: 'tcx, 'tcx: 'a> {
tcx: TyCtxt<'a, 'gcx, 'tcx>,
mir: &'a Mir<'tcx>,
scope_tree: Rc<region::ScopeTree>,
root_scope: Option<region::Scope>,
borrows: IndexVec<BorrowIndex, BorrowData<'tcx>>,
location_map: FxHashMap<Location, BorrowIndex>,
region_map: FxHashMap<Region<'tcx>, FxHashSet<BorrowIndex>>,
local_map: FxHashMap<mir::Local, FxHashSet<BorrowIndex>>,
region_span_map: FxHashMap<RegionKind, Span>,
nonlexical_regioncx: Option<RegionInferenceContext<'tcx>>,
}
@ -69,22 +76,32 @@ impl<'tcx> fmt::Display for BorrowData<'tcx> {
impl<'a, 'gcx, 'tcx> Borrows<'a, 'gcx, 'tcx> {
pub fn new(tcx: TyCtxt<'a, 'gcx, 'tcx>,
mir: &'a Mir<'tcx>,
nonlexical_regioncx: Option<RegionInferenceContext<'tcx>>)
nonlexical_regioncx: Option<RegionInferenceContext<'tcx>>,
def_id: DefId,
body_id: Option<hir::BodyId>)
-> Self {
let scope_tree = tcx.region_scope_tree(def_id);
let root_scope = body_id.map(|body_id| {
region::Scope::CallSite(tcx.hir.body(body_id).value.hir_id.local_id)
});
let mut visitor = GatherBorrows {
tcx,
mir,
idx_vec: IndexVec::new(),
location_map: FxHashMap(),
region_map: FxHashMap(),
local_map: FxHashMap(),
region_span_map: FxHashMap()
};
visitor.visit_mir(mir);
return Borrows { tcx: tcx,
mir: mir,
borrows: visitor.idx_vec,
scope_tree,
root_scope,
location_map: visitor.location_map,
region_map: visitor.region_map,
local_map: visitor.local_map,
region_span_map: visitor.region_span_map,
nonlexical_regioncx };
@ -94,6 +111,7 @@ impl<'a, 'gcx, 'tcx> Borrows<'a, 'gcx, 'tcx> {
idx_vec: IndexVec<BorrowIndex, BorrowData<'tcx>>,
location_map: FxHashMap<Location, BorrowIndex>,
region_map: FxHashMap<Region<'tcx>, FxHashSet<BorrowIndex>>,
local_map: FxHashMap<mir::Local, FxHashSet<BorrowIndex>>,
region_span_map: FxHashMap<RegionKind, Span>,
}
@ -101,6 +119,14 @@ impl<'a, 'gcx, 'tcx> Borrows<'a, 'gcx, 'tcx> {
fn visit_rvalue(&mut self,
rvalue: &mir::Rvalue<'tcx>,
location: mir::Location) {
fn root_local(mut p: &mir::Place<'_>) -> Option<mir::Local> {
loop { match p {
mir::Place::Projection(pi) => p = &pi.base,
mir::Place::Static(_) => return None,
mir::Place::Local(l) => return Some(*l)
}}
}
if let mir::Rvalue::Ref(region, kind, ref place) = *rvalue {
if is_unsafe_place(self.tcx, self.mir, place) { return; }
@ -109,8 +135,14 @@ impl<'a, 'gcx, 'tcx> Borrows<'a, 'gcx, 'tcx> {
};
let idx = self.idx_vec.push(borrow);
self.location_map.insert(location, idx);
let borrows = self.region_map.entry(region).or_insert(FxHashSet());
borrows.insert(idx);
if let Some(local) = root_local(place) {
let borrows = self.local_map.entry(local).or_insert(FxHashSet());
borrows.insert(idx);
}
}
}
@ -199,7 +231,7 @@ impl<'a, 'gcx, 'tcx> BitDenotation for Borrows<'a, 'gcx, 'tcx> {
mir::StatementKind::EndRegion(region_scope) => {
if let Some(borrow_indexes) = self.region_map.get(&ReScope(region_scope)) {
assert!(self.nonlexical_regioncx.is_none());
for idx in borrow_indexes { sets.kill(&idx); }
sets.kill_all(borrow_indexes);
} else {
// (if there is no entry, then there are no borrows to be tracked)
}
@ -224,10 +256,19 @@ impl<'a, 'gcx, 'tcx> BitDenotation for Borrows<'a, 'gcx, 'tcx> {
}
}
mir::StatementKind::StorageDead(local) => {
// Make sure there are no remaining borrows for locals that
// are gone out of scope.
//
// FIXME: expand this to variables that are assigned over.
if let Some(borrow_indexes) = self.local_map.get(&local) {
sets.kill_all(borrow_indexes);
}
}
mir::StatementKind::InlineAsm { .. } |
mir::StatementKind::SetDiscriminant { .. } |
mir::StatementKind::StorageLive(..) |
mir::StatementKind::StorageDead(..) |
mir::StatementKind::Validate(..) |
mir::StatementKind::Nop => {}
@ -253,8 +294,17 @@ impl<'a, 'gcx, 'tcx> BitDenotation for Borrows<'a, 'gcx, 'tcx> {
// like unwind paths, we do not always emit `EndRegion` statements, so we
// add some kills here as a "backup" and to avoid spurious error messages.
for (borrow_index, borrow_data) in self.borrows.iter_enumerated() {
if let ReScope(..) = borrow_data.region {
sets.kill(&borrow_index);
if let ReScope(scope) = borrow_data.region {
// Check that the scope is not actually a scope from a function that is
// a parent of our closure. Note that the CallSite scope itself is
// *outside* of the closure, for some weird reason.
if let Some(root_scope) = self.root_scope {
if *scope != root_scope &&
self.scope_tree.is_subscope_of(*scope, root_scope)
{
sets.kill(&borrow_index);
}
}
}
}
}

92
src/librustc_mir/dataflow/impls/mod.rs
View File

@ -14,7 +14,6 @@
use rustc::ty::TyCtxt;
use rustc::mir::{self, Mir, Location};
use rustc_data_structures::bitslice::BitSlice; // adds set_bit/get_bit to &[usize] bitvector rep.
use rustc_data_structures::bitslice::{BitwiseOperator};
use rustc_data_structures::indexed_set::{IdxSet};
use rustc_data_structures::indexed_vec::Idx;
@ -504,7 +503,6 @@ impl<'a, 'gcx, 'tcx> BitDenotation for MovingOutStatements<'a, 'gcx, 'tcx> {
let stmt = &mir[location.block].statements[location.statement_index];
let loc_map = &move_data.loc_map;
let path_map = &move_data.path_map;
let bits_per_block = self.bits_per_block();
match stmt.kind {
// this analysis only tries to find moves explicitly
@ -515,21 +513,15 @@ impl<'a, 'gcx, 'tcx> BitDenotation for MovingOutStatements<'a, 'gcx, 'tcx> {
_ => {
debug!("stmt {:?} at loc {:?} moves out of move_indexes {:?}",
stmt, location, &loc_map[location]);
for move_index in &loc_map[location] {
// Every path deinitialized by a *particular move*
// has corresponding bit, "gen'ed" (i.e. set)
// here, in dataflow vector
zero_to_one(sets.gen_set.words_mut(), *move_index);
}
// Every path deinitialized by a *particular move*
// has corresponding bit, "gen'ed" (i.e. set)
// here, in dataflow vector
sets.gen_all_and_assert_dead(&loc_map[location]);
}
}
for_location_inits(tcx, mir, move_data, location,
|mpi| for moi in &path_map[mpi] {
assert!(moi.index() < bits_per_block);
sets.kill_set.add(&moi);
}
);
|mpi| sets.kill_all(&path_map[mpi]));
}
fn terminator_effect(&self,
@ -543,18 +535,10 @@ impl<'a, 'gcx, 'tcx> BitDenotation for MovingOutStatements<'a, 'gcx, 'tcx> {
debug!("terminator {:?} at loc {:?} moves out of move_indexes {:?}",
term, location, &loc_map[location]);
let bits_per_block = self.bits_per_block();
for move_index in &loc_map[location] {
assert!(move_index.index() < bits_per_block);
zero_to_one(sets.gen_set.words_mut(), *move_index);
}
sets.gen_all_and_assert_dead(&loc_map[location]);
for_location_inits(tcx, mir, move_data, location,
|mpi| for moi in &path_map[mpi] {
assert!(moi.index() < bits_per_block);
sets.kill_set.add(&moi);
}
);
|mpi| sets.kill_all(&path_map[mpi]));
}
fn propagate_call_return(&self,
@ -585,11 +569,7 @@ impl<'a, 'gcx, 'tcx> BitDenotation for EverInitializedLvals<'a, 'gcx, 'tcx> {
}
fn start_block_effect(&self, sets: &mut BlockSets<InitIndex>) {
let bits_per_block = self.bits_per_block();
for init_index in (0..self.mir.arg_count).map(InitIndex::new) {
assert!(init_index.index() < bits_per_block);
sets.gen_set.add(&init_index);
}
sets.gen_all((0..self.mir.arg_count).map(InitIndex::new));
}
fn statement_effect(&self,
sets: &mut BlockSets<InitIndex>,
@ -599,26 +579,39 @@ impl<'a, 'gcx, 'tcx> BitDenotation for EverInitializedLvals<'a, 'gcx, 'tcx> {
let init_path_map = &move_data.init_path_map;
let init_loc_map = &move_data.init_loc_map;
let rev_lookup = &move_data.rev_lookup;
let bits_per_block = self.bits_per_block();
debug!("statement {:?} at loc {:?} initializes move_indexes {:?}",
stmt, location, &init_loc_map[location]);
for init_index in &init_loc_map[location] {
assert!(init_index.index() < bits_per_block);
sets.gen_set.add(init_index);
}
sets.gen_all(&init_loc_map[location]);
match stmt.kind {
mir::StatementKind::StorageDead(local) => {
// End inits for StorageDead, so that an immutable variable can
// be reinitialized on the next iteration of the loop.
mir::StatementKind::StorageDead(local) |
mir::StatementKind::StorageLive(local) => {
// End inits for StorageDead and StorageLive, so that an immutable
// variable can be reinitialized on the next iteration of the loop.
//
// FIXME(#46525): We *need* to do this for StorageLive as well as
// StorageDead, because lifetimes of match bindings with guards are
// weird - i.e. this code
//
// ```
// fn main() {
// match 0 {
// a | a
// if { println!("a={}", a); false } => {}
// _ => {}
// }
// }
// ```
//
// runs the guard twice, using the same binding for `a`, and only
// storagedeads after everything ends, so if we don't regard the
// storagelive as killing storage, we would have a multiple assignment
// to immutable data error.
if let LookupResult::Exact(mpi) = rev_lookup.find(&mir::Place::Local(local)) {
debug!("stmt {:?} at loc {:?} clears the ever initialized status of {:?}",
stmt, location, &init_path_map[mpi]);
for ii in &init_path_map[mpi] {
assert!(ii.index() < bits_per_block);
sets.kill_set.add(&ii);
}
stmt, location, &init_path_map[mpi]);
sets.kill_all(&init_path_map[mpi]);
}
}
_ => {}
@ -634,13 +627,11 @@ impl<'a, 'gcx, 'tcx> BitDenotation for EverInitializedLvals<'a, 'gcx, 'tcx> {
let init_loc_map = &move_data.init_loc_map;
debug!("terminator {:?} at loc {:?} initializes move_indexes {:?}",
term, location, &init_loc_map[location]);
let bits_per_block = self.bits_per_block();
for init_index in &init_loc_map[location] {
if move_data.inits[*init_index].kind != InitKind::NonPanicPathOnly {
assert!(init_index.index() < bits_per_block);
sets.gen_set.add(init_index);
}
}
sets.gen_all(
init_loc_map[location].iter().filter(|init_index| {
move_data.inits[**init_index].kind != InitKind::NonPanicPathOnly
})
);
}
fn propagate_call_return(&self,
@ -663,11 +654,6 @@ impl<'a, 'gcx, 'tcx> BitDenotation for EverInitializedLvals<'a, 'gcx, 'tcx> {
}
}
fn zero_to_one(bitvec: &mut [usize], move_index: MoveOutIndex) {
let retval = bitvec.set_bit(move_index.index());
assert!(retval);
}
impl<'a, 'gcx, 'tcx> BitwiseOperator for MaybeInitializedLvals<'a, 'gcx, 'tcx> {
#[inline]
fn join(&self, pred1: usize, pred2: usize) -> usize {

30
src/librustc_mir/dataflow/mod.rs
View File

@ -18,6 +18,7 @@ use rustc::ty::{self, TyCtxt};
use rustc::mir::{self, Mir, BasicBlock, BasicBlockData, Location, Statement, Terminator};
use rustc::session::Session;
use std::borrow::Borrow;
use std::fmt::{self, Debug};
use std::io;
use std::mem;
@ -492,10 +493,39 @@ impl<'a, E:Idx> BlockSets<'a, E> {
self.gen_set.add(e);
self.kill_set.remove(e);
}
fn gen_all<I>(&mut self, i: I)
where I: IntoIterator,
I::Item: Borrow<E>
{
for j in i {
self.gen(j.borrow());
}
}
fn gen_all_and_assert_dead<I>(&mut self, i: I)
where I: IntoIterator,
I::Item: Borrow<E>
{
for j in i {
let j = j.borrow();
let retval = self.gen_set.add(j);
self.kill_set.remove(j);
assert!(retval);
}
}
fn kill(&mut self, e: &E) {
self.gen_set.remove(e);
self.kill_set.add(e);
}
fn kill_all<I>(&mut self, i: I)
where I: IntoIterator,
I::Item: Borrow<E>
{
for j in i {
self.kill(j.borrow());
}
}
}
impl<E:Idx> AllSets<E> {

2
src/test/compile-fail/borrowck/borrowck-local-borrow-outlives-fn.rs
View File

@ -13,7 +13,7 @@
fn cplusplus_mode(x: isize) -> &'static isize {
&x //[ast]~ ERROR `x` does not live long enough
//[mir]~^ ERROR borrowed value does not live long enough
}
//[mir]~^ ERROR borrowed value does not live long enough
fn main() {}

2
src/test/compile-fail/borrowck/borrowck-local-borrow-with-panic-outlives-fn.rs
View File

@ -14,9 +14,9 @@
fn cplusplus_mode_exceptionally_unsafe(x: &mut Option<&'static mut isize>) {
let mut z = (0, 0);
*x = Some(&mut z.1); //[ast]~ ERROR [E0597]
//[mir]~^ ERROR [E0597]
panic!("catch me for a dangling pointer!")
}
//[mir]~^ ERROR [E0597]
fn main() {
cplusplus_mode_exceptionally_unsafe(&mut None);

6
src/test/compile-fail/borrowck/borrowck-move-moved-value-into-closure.rs
View File

@ -8,6 +8,9 @@
// option. This file may not be copied, modified, or distributed
// except according to those terms.
// revisions: ast mir
//[mir]compile-flags: -Z borrowck=mir
#![feature(box_syntax)]
fn call_f<F:FnOnce() -> isize>(f: F) -> isize {
@ -18,5 +21,6 @@ fn main() {
let t: Box<_> = box 3;
call_f(move|| { *t + 1 });
call_f(move|| { *t + 1 }); //~ ERROR capture of moved value
call_f(move|| { *t + 1 }); //[ast]~ ERROR capture of moved value
//[mir]~^ ERROR use of moved value
}

10
src/test/compile-fail/borrowck/borrowck-mut-borrow-linear-errors.rs
View File

@ -23,15 +23,9 @@ fn main() {
1 => { addr = &mut x; } //[ast]~ ERROR [E0499]
//[mir]~^ ERROR [E0499]
2 => { addr = &mut x; } //[ast]~ ERROR [E0499]
//[mir]~^ ERROR [E0506]
//[mir]~| ERROR [E0499]
//[mir]~| ERROR [E0499]
//[mir]~^ ERROR [E0499]
_ => { addr = &mut x; } //[ast]~ ERROR [E0499]
//[mir]~^ ERROR [E0506]
//[mir]~| ERROR [E0499]
//[mir]~| ERROR [E0499]
//[mir]~^ ERROR [E0499]
}
}
}

1
src/test/compile-fail/borrowck/borrowck-thread-local-static-borrow-outlives-fn.rs
View File

@ -8,6 +8,7 @@
// option. This file may not be copied, modified, or distributed
// except according to those terms.
// ignore-test will be fixed later
// revisions: ast mir
//[mir]compile-flags: -Z borrowck=mir

13
src/test/compile-fail/borrowck/borrowck-union-borrow.rs
View File

@ -52,12 +52,12 @@ fn main() {
{
let ra = &u.a;
let rmb = &mut u.b; //[ast]~ ERROR cannot borrow `u` (via `u.b`) as mutable because `u` is also borrowed as immutable (via `u.a`)
// FIXME Error for MIR (needs support for union)
//[mir]~^ ERROR cannot borrow `u.b` as mutable because it is also borrowed as immutable
}
{
let ra = &u.a;
u.b = 1; //[ast]~ ERROR cannot assign to `u.b` because it is borrowed
// FIXME Error for MIR (needs support for union)
//[mir]~^ ERROR cannot assign to `u.b` because it is borrowed
}
// Mut borrow, same field
{
@ -84,22 +84,23 @@ fn main() {
{
let rma = &mut u.a;
let rb = &u.b; //[ast]~ ERROR cannot borrow `u` (via `u.b`) as immutable because `u` is also borrowed as mutable (via `u.a`)
// FIXME Error for MIR (needs support for union)
//[mir]~^ ERROR cannot borrow `u.b` as immutable because it is also borrowed as mutable
}
{
let ra = &mut u.a;
let b = u.b; //[ast]~ ERROR cannot use `u.b` because it was mutably borrowed
// FIXME Error for MIR (needs support for union)
//[mir]~^ ERROR cannot use `u.b` because it was mutably borrowed
}
{
let rma = &mut u.a;
let rmb2 = &mut u.b; //[ast]~ ERROR cannot borrow `u` (via `u.b`) as mutable more than once at a time
// FIXME Error for MIR (needs support for union)
//[mir]~^ ERROR cannot borrow `u.b` as mutable more than once at a time
}
{
let rma = &mut u.a;
u.b = 1; //[ast]~ ERROR cannot assign to `u.b` because it is borrowed
// FIXME Error for MIR (needs support for union)
//[mir]~^ ERROR cannot assign to `u.b` because it is borrowed
}
}
}

3
src/test/compile-fail/borrowck/borrowck-vec-pattern-move-tail.rs
View File

@ -1,3 +1,4 @@
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
@ -22,7 +23,7 @@ fn main() {
println!("t[0]: {}", t[0]);
a[2] = 0; //[ast]~ ERROR cannot assign to `a[..]` because it is borrowed
//[cmp]~^ ERROR cannot assign to `a[..]` because it is borrowed (Ast)
// FIXME Error for MIR (error missed)
//[cmp]~| ERROR cannot assign to `a[..]` because it is borrowed (Mir)
println!("t[0]: {}", t[0]);
t[0];
}

6
src/test/compile-fail/issue-25579.rs
View File

@ -20,13 +20,9 @@ fn causes_ice(mut l: &mut Sexpression) {
loop { match l {
&mut Sexpression::Num(ref mut n) => {},
&mut Sexpression::Cons(ref mut expr) => { //[ast]~ ERROR [E0499]
//[mir]~^ ERROR [E0506]
//[mir]~| ERROR [E0499]
//[mir]~^ ERROR [E0499]
l = &mut **expr; //[ast]~ ERROR [E0506]
//[mir]~^ ERROR [E0506]
//[mir]~| ERROR [E0506]
//[mir]~| ERROR [E0499]
//[mir]~| ERROR [E0499]
}
}}
}

10
src/test/compile-fail/region-borrow-params-issue-29793-big.rs
View File

@ -16,6 +16,10 @@
// behavior (because the improperly accepted closure was actually
// able to be invoked).
// ignore-tidy-linelength
// revisions: ast mir
//[mir]compile-flags: -Z borrowck=mir
struct WrapA<F>(Option<F>);
impl<F> WrapA<F> {
@ -75,9 +79,11 @@ impl<F, T> WrapA<F>
fn main() {
let mut w = WrapA::new().set(|x: usize, y: usize| {
WrapB::new().set(|t: bool| if t { x } else { y }) // (separate errors for `x` vs `y`)
//~^ ERROR `x` does not live long enough
//~| ERROR `y` does not live long enough
//[ast]~^ ERROR `x` does not live long enough
//[ast]~| ERROR `y` does not live long enough
});
//[mir]~^ ERROR borrowed value does not live long enough
//[mir]~| ERROR borrowed value does not live long enough
w.handle(); // This works
// w.handle_ref(); // This doesn't

1
src/test/run-pass/match-pipe-binding.rs
View File

@ -8,6 +8,7 @@
// option. This file may not be copied, modified, or distributed
// except according to those terms.
// compile-flags: -Z borrowck=compare
fn test1() {
// from issue 6338