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use rustc::hir;
use rustc::mir::*;
use rustc::ty;
use rustc_data_structures::indexed_vec::Idx;
use rustc_errors::DiagnosticBuilder;
use syntax_pos::Span;
use borrow_check::MirBorrowckCtxt;
use dataflow::move_paths::{IllegalMoveOrigin, IllegalMoveOriginKind};
use dataflow::move_paths::{LookupResult, MoveError, MovePathIndex};
use util::borrowck_errors::{BorrowckErrors, Origin};
#[derive(Debug)]
enum GroupedMoveError<'tcx> {
MovesFromMatchPlace {
span: Span,
move_from: Place<'tcx>,
kind: IllegalMoveOriginKind<'tcx>,
binds_to: Vec<Local>,
},
MovesFromPattern {
span: Span,
move_from: MovePathIndex,
kind: IllegalMoveOriginKind<'tcx>,
binds_to: Vec<Local>,
},
OtherIllegalMove {
span: Span,
kind: IllegalMoveOriginKind<'tcx>,
},
}
impl<'a, 'gcx, 'tcx> MirBorrowckCtxt<'a, 'gcx, 'tcx> {
pub(crate) fn report_move_errors(&mut self, move_errors: Vec<MoveError<'tcx>>) {
let grouped_errors = self.group_move_errors(move_errors);
for error in grouped_errors {
self.report(error);
}
}
fn group_move_errors(&self, errors: Vec<MoveError<'tcx>>) -> Vec<GroupedMoveError<'tcx>> {
let mut grouped_errors = Vec::new();
for error in errors {
self.append_to_grouped_errors(&mut grouped_errors, error);
}
grouped_errors
}
fn append_to_grouped_errors(
&self,
grouped_errors: &mut Vec<GroupedMoveError<'tcx>>,
error: MoveError<'tcx>,
) {
match error {
MoveError::UnionMove { .. } => {
unimplemented!("don't know how to report union move errors yet.")
}
MoveError::IllegalMove {
cannot_move_out_of: IllegalMoveOrigin { location, kind },
} => {
let stmt_source_info = self.mir.source_info(location);
if let Some(StatementKind::Assign(
Place::Local(local),
Rvalue::Use(Operand::Move(move_from)),
)) = self.mir.basic_blocks()[location.block]
.statements
.get(location.statement_index)
.map(|stmt| &stmt.kind)
{
let local_decl = &self.mir.local_decls[*local];
if let Some(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
opt_match_place: Some((ref opt_match_place, match_span)),
binding_mode: _,
opt_ty_info: _,
}))) = local_decl.is_user_variable
{
self.append_binding_error(
grouped_errors,
kind,
move_from,
*local,
opt_match_place,
match_span,
stmt_source_info.span,
);
return;
}
}
grouped_errors.push(GroupedMoveError::OtherIllegalMove {
span: stmt_source_info.span,
kind,
});
}
}
}
fn append_binding_error(
&self,
grouped_errors: &mut Vec<GroupedMoveError<'tcx>>,
kind: IllegalMoveOriginKind<'tcx>,
move_from: &Place<'tcx>,
bind_to: Local,
match_place: &Option<Place<'tcx>>,
match_span: Span,
statement_span: Span,
) {
debug!(
"append_to_grouped_errors(match_place={:?}, match_span={:?})",
match_place, match_span
);
let from_simple_let = match_place.is_none();
let match_place = match_place.as_ref().unwrap_or(move_from);
match self.move_data.rev_lookup.find(match_place) {
LookupResult::Parent(_) => {
for ge in &mut *grouped_errors {
if let GroupedMoveError::MovesFromMatchPlace { span, binds_to, .. } = ge {
if match_span == *span {
debug!("appending local({:?}) to list", bind_to);
if !binds_to.is_empty() {
binds_to.push(bind_to);
}
return;
}
}
}
debug!("found a new move error location");
let (binds_to, span) = if from_simple_let {
(vec![], statement_span)
} else {
(vec![bind_to], match_span)
};
grouped_errors.push(GroupedMoveError::MovesFromMatchPlace {
span,
move_from: match_place.clone(),
kind,
binds_to,
});
}
LookupResult::Exact(_) => {
let mpi = match self.move_data.rev_lookup.find(move_from) {
LookupResult::Parent(Some(mpi)) => mpi,
_ => unreachable!("Probably not unreachable..."),
};
for ge in &mut *grouped_errors {
if let GroupedMoveError::MovesFromPattern {
span,
move_from: other_mpi,
binds_to,
..
} = ge
{
if match_span == *span && mpi == *other_mpi {
debug!("appending local({:?}) to list", bind_to);
binds_to.push(bind_to);
return;
}
}
}
debug!("found a new move error location");
grouped_errors.push(GroupedMoveError::MovesFromPattern {
span: match_span,
move_from: mpi,
kind,
binds_to: vec![bind_to],
});
}
};
}
fn report(&mut self, error: GroupedMoveError<'tcx>) {
let (mut err, err_span) = {
let (span, kind): (Span, &IllegalMoveOriginKind) = match error {
GroupedMoveError::MovesFromMatchPlace { span, ref kind, .. }
| GroupedMoveError::MovesFromPattern { span, ref kind, .. }
| GroupedMoveError::OtherIllegalMove { span, ref kind } => (span, kind),
};
let origin = Origin::Mir;
(
match kind {
IllegalMoveOriginKind::Static => {
self.tcx.cannot_move_out_of(span, "static item", origin)
}
IllegalMoveOriginKind::BorrowedContent { target_place: place } => {
let ty = place.ty(self.mir, self.tcx).to_ty(self.tcx);
match ty.sty {
ty::TyArray(..) | ty::TySlice(..) => self
.tcx
.cannot_move_out_of_interior_noncopy(span, ty, None, origin),
ty::TyClosure(def_id, closure_substs)
if !self.mir.upvar_decls.is_empty()
&& {
match place {
Place::Projection(ref proj) => {
proj.base == Place::Local(Local::new(1))
}
Place::Promoted(_) |
Place::Local(_) | Place::Static(_) => unreachable!(),
}
} =>
{
let closure_kind_ty =
closure_substs.closure_kind_ty(def_id, self.tcx);
let closure_kind = closure_kind_ty.to_opt_closure_kind();
let place_description = match closure_kind {
Some(ty::ClosureKind::Fn) => {
"captured variable in an `Fn` closure"
}
Some(ty::ClosureKind::FnMut) => {
"captured variable in an `FnMut` closure"
}
Some(ty::ClosureKind::FnOnce) => {
bug!("closure kind does not match first argument type")
}
None => bug!("closure kind not inferred by borrowck"),
};
self.tcx.cannot_move_out_of(span, place_description, origin)
}
_ => self
.tcx
.cannot_move_out_of(span, "borrowed content", origin),
}
}
IllegalMoveOriginKind::InteriorOfTypeWithDestructor { container_ty: ty } => {
self.tcx
.cannot_move_out_of_interior_of_drop(span, ty, origin)
}
IllegalMoveOriginKind::InteriorOfSliceOrArray { ty, is_index } => self
.tcx
.cannot_move_out_of_interior_noncopy(span, ty, Some(*is_index), origin),
},
span,
)
};
self.add_move_hints(error, &mut err, err_span);
err.buffer(&mut self.errors_buffer);
}
fn add_move_hints(
&self,
error: GroupedMoveError<'tcx>,
err: &mut DiagnosticBuilder<'a>,
span: Span,
) {
match error {
GroupedMoveError::MovesFromMatchPlace {
mut binds_to,
move_from,
..
} => {
if let Ok(snippet) = self.tcx.sess.codemap().span_to_snippet(span) {
match move_from {
Place::Projection(ref proj)
if self.suitable_to_remove_deref(proj, &snippet) =>
{
err.span_suggestion(
span,
"consider removing this dereference operator",
(&snippet[1..]).to_owned(),
);
}
_ => {
err.span_suggestion(
span,
"consider using a reference instead",
format!("&{}", snippet),
);
}
}
binds_to.sort();
binds_to.dedup();
for local in binds_to {
let bind_to = &self.mir.local_decls[local];
let binding_span = bind_to.source_info.span;
err.span_label(
binding_span,
format!(
"move occurs because {} has type `{}`, \
which does not implement the `Copy` trait",
bind_to.name.unwrap(),
bind_to.ty
),
);
}
}
}
GroupedMoveError::MovesFromPattern { mut binds_to, .. } => {
binds_to.sort();
binds_to.dedup();
for local in binds_to {
let bind_to = &self.mir.local_decls[local];
let binding_span = bind_to.source_info.span;
let ref_kind = match bind_to.mutability {
Mutability::Not => "ref",
Mutability::Mut => "ref mut",
};
match bind_to.name {
Some(name) => {
err.span_suggestion(
binding_span,
"to prevent move, use ref or ref mut",
format!("{} {:?}", ref_kind, name),
);
}
None => {
err.span_label(
span,
format!("Local {:?} is not suitable for ref", bind_to),
);
}
}
}
}
GroupedMoveError::OtherIllegalMove { .. } => (),
}
}
fn suitable_to_remove_deref(&self, proj: &PlaceProjection<'tcx>, snippet: &str) -> bool {
let is_shared_ref = |ty: ty::Ty| match ty.sty {
ty::TypeVariants::TyRef(.., hir::Mutability::MutImmutable) => true,
_ => false,
};
proj.elem == ProjectionElem::Deref && snippet.starts_with('*') && match proj.base {
Place::Local(local) => {
let local_decl = &self.mir.local_decls[local];
local_decl.is_user_variable.is_some() && is_shared_ref(local_decl.ty)
}
Place::Promoted(_) => true,
Place::Static(ref st) => is_shared_ref(st.ty),
Place::Projection(ref proj) => match proj.elem {
ProjectionElem::Field(_, ty) => is_shared_ref(ty),
_ => false,
},
}
}
}