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Fix printing of upvar in closures

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This commit is contained in:
Ramana Venkata 2017-11-12 21:49:02 +05:30
parent a6d691b43c
commit 5144d3222f
2 changed files with 70 additions and 36 deletions
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82
src/librustc_mir/borrow_check.rs
View File

@ -11,7 +11,6 @@
//! This query borrow-checks the MIR to (further) ensure it is not broken.
use rustc::hir;
use rustc::hir::def::Def;
use rustc::hir::def_id::{DefId};
use rustc::infer::{InferCtxt};
use rustc::ty::{self, TyCtxt, ParamEnv};
@ -1022,7 +1021,7 @@ fn each_borrow_involving_path<F>(&mut self,
access_lvalue: (ShallowOrDeep, &Lvalue<'tcx>),
flow_state: &InProgress<'b, 'gcx, 'tcx>,
mut op: F)
where F: FnMut(&mut Self, BorrowIndex, &BorrowData<'tcx>, &Lvalue) -> Control
where F: FnMut(&mut Self, BorrowIndex, &BorrowData<'tcx>, &Lvalue<'tcx>) -> Control
{
let (access, lvalue) = access_lvalue;
@ -1249,7 +1248,7 @@ impl<'c, 'b, 'a: 'b+'c, 'gcx, 'tcx: 'a> MirBorrowckCtxt<'c, 'b, 'a, 'gcx, 'tcx>
fn report_use_of_moved_or_uninitialized(&mut self,
_context: Context,
desired_action: &str,
(lvalue, span): (&Lvalue, Span),
(lvalue, span): (&Lvalue<'tcx>, Span),
mpi: MovePathIndex,
curr_move_out: &IdxSetBuf<MoveOutIndex>) {
@ -1291,8 +1290,8 @@ fn report_use_of_moved_or_uninitialized(&mut self,
fn report_move_out_while_borrowed(&mut self,
_context: Context,
(lvalue, span): (&Lvalue, Span),
borrow: &BorrowData) {
(lvalue, span): (&Lvalue<'tcx>, Span),
borrow: &BorrowData<'tcx>) {
self.tcx.cannot_move_when_borrowed(span,
&self.describe_lvalue(lvalue),
Origin::Mir)
@ -1306,8 +1305,8 @@ fn report_move_out_while_borrowed(&mut self,
fn report_use_while_mutably_borrowed(&mut self,
_context: Context,
(lvalue, span): (&Lvalue, Span),
borrow : &BorrowData) {
(lvalue, span): (&Lvalue<'tcx>, Span),
borrow : &BorrowData<'tcx>) {
let mut err = self.tcx.cannot_use_when_mutably_borrowed(
span, &self.describe_lvalue(lvalue),
@ -1383,8 +1382,8 @@ fn find_closure_span(
fn report_conflicting_borrow(&mut self,
context: Context,
common_prefix: &Lvalue,
(lvalue, span): (&Lvalue, Span),
common_prefix: &Lvalue<'tcx>,
(lvalue, span): (&Lvalue<'tcx>, Span),
gen_borrow_kind: BorrowKind,
issued_borrow: &BorrowData,
end_issued_loan_span: Option<Span>) {
@ -1454,7 +1453,7 @@ fn report_conflicting_borrow(&mut self,
fn report_illegal_mutation_of_borrowed(&mut self,
_: Context,
(lvalue, span): (&Lvalue, Span),
(lvalue, span): (&Lvalue<'tcx>, Span),
loan: &BorrowData) {
let mut err = self.tcx.cannot_assign_to_borrowed(
span, self.retrieve_borrow_span(loan), &self.describe_lvalue(lvalue), Origin::Mir);
@ -1464,7 +1463,7 @@ fn report_illegal_mutation_of_borrowed(&mut self,
fn report_illegal_reassignment(&mut self,
_context: Context,
(lvalue, span): (&Lvalue, Span),
(lvalue, span): (&Lvalue<'tcx>, Span),
assigned_span: Span) {
self.tcx.cannot_reassign_immutable(span,
&self.describe_lvalue(lvalue),
@ -1475,7 +1474,9 @@ fn report_illegal_reassignment(&mut self,
.emit();
}
fn report_assignment_to_static(&mut self, _context: Context, (lvalue, span): (&Lvalue, Span)) {
fn report_assignment_to_static(&mut self,
_context: Context,
(lvalue, span): (&Lvalue<'tcx>, Span)) {
let mut err = self.tcx.cannot_assign_static(
span, &self.describe_lvalue(lvalue), Origin::Mir);
err.emit();
@ -1484,14 +1485,17 @@ fn report_assignment_to_static(&mut self, _context: Context, (lvalue, span): (&L
impl<'c, 'b, 'a: 'b+'c, 'gcx, 'tcx: 'a> MirBorrowckCtxt<'c, 'b, 'a, 'gcx, 'tcx> {
// End-user visible description of `lvalue`
fn describe_lvalue(&self, lvalue: &Lvalue) -> String {
fn describe_lvalue(&self, lvalue: &Lvalue<'tcx>) -> String {
let mut buf = String::new();
self.append_lvalue_to_string(lvalue, &mut buf, None);
buf
}
// Appends end-user visible description of `lvalue` to `buf`.
fn append_lvalue_to_string(&self, lvalue: &Lvalue, buf: &mut String, autoderef: Option<bool>) {
fn append_lvalue_to_string(&self,
lvalue: &Lvalue<'tcx>,
buf: &mut String,
autoderef: Option<bool>) {
match *lvalue {
Lvalue::Local(local) => {
self.append_local_to_string(local, buf, "_");
@ -1501,41 +1505,50 @@ fn append_lvalue_to_string(&self, lvalue: &Lvalue, buf: &mut String, autoderef:
}
Lvalue::Projection(ref proj) => {
let mut autoderef = autoderef.unwrap_or(false);
let (prefix, suffix, index_operand) = match proj.elem {
match proj.elem {
ProjectionElem::Deref => {
if autoderef {
("", format!(""), None)
self.append_lvalue_to_string(&proj.base, buf, Some(autoderef));
} else {
("(*", format!(")"), None)
buf.push_str(&"(*");
self.append_lvalue_to_string(&proj.base, buf, Some(autoderef));
buf.push_str(&")");
}
},
ProjectionElem::Downcast(..) =>
("", format!(""), None), // (dont emit downcast info)
ProjectionElem::Downcast(..) => {
self.append_lvalue_to_string(&proj.base, buf, Some(autoderef));
},
ProjectionElem::Field(field, _ty) => {
autoderef = true;
("", format!(".{}", self.describe_field(&proj.base, field.index())), None)
let is_projection_from_ty_closure = proj.base.ty(self.mir, self.tcx)
.to_ty(self.tcx).is_closure();
let field_name = self.describe_field(&proj.base, field.index());
if is_projection_from_ty_closure {
buf.push_str(&format!("{}", field_name));
} else {
self.append_lvalue_to_string(&proj.base, buf, Some(autoderef));
buf.push_str(&format!(".{}", field_name));
}
},
ProjectionElem::Index(index) => {
autoderef = true;
("", format!(""), Some(index))
self.append_lvalue_to_string(&proj.base, buf, Some(autoderef));
buf.push_str("[");
self.append_local_to_string(index, buf, "..");
buf.push_str("]");
},
ProjectionElem::ConstantIndex { .. } | ProjectionElem::Subslice { .. } => {
autoderef = true;
// Since it isn't possible to borrow an element on a particular index and
// then use another while the borrow is held, don't output indices details
// to avoid confusing the end-user
("", format!("[..]"), None)
self.append_lvalue_to_string(&proj.base, buf, Some(autoderef));
buf.push_str(&"[..]");
},
};
buf.push_str(prefix);
self.append_lvalue_to_string(&proj.base, buf, Some(autoderef));
if let Some(index) = index_operand {
buf.push_str("[");
self.append_local_to_string(index, buf, "..");
buf.push_str("]");
} else {
buf.push_str(&suffix);
}
}
}
}
@ -1609,12 +1622,9 @@ fn describe_field_from_ty(&self, ty: &ty::Ty, field_index: usize) -> String {
// the closure comes from another crate. But in that case we wouldn't
// be borrowck'ing it, so we can just unwrap:
let node_id = self.tcx.hir.as_local_node_id(closure_def_id).unwrap();
let local_def = self.tcx.with_freevars(node_id, |fv| fv[field_index].def);
let freevar = self.tcx.with_freevars(node_id, |fv| fv[field_index]);
match local_def {
Def::Local(local_node_id) => self.tcx.hir.name(local_node_id).to_string(),
_ => unreachable!()
}
self.tcx.hir.name(freevar.var_id()).to_string()
}
_ => {
// Might need a revision when the fields in trait RFC is implemented

24
src/test/compile-fail/borrowck/borrowck-describe-lvalue.rs
View File

@ -327,4 +327,28 @@ unsafe fn bump2(mut block: *mut Block2) {
_ => panic!("other case")
}
}
// Field from upvar
{
let mut x = 0;
|| {
let y = &mut x;
&mut x; //[ast]~ ERROR cannot borrow `**x` as mutable more than once at a time
//[mir]~^ ERROR cannot borrow `**x` as mutable more than once at a time (Ast)
//[mir]~| ERROR cannot borrow `(*x)` as mutable more than once at a time (Mir)
*y = 1;
};
}
// Field from upvar nested
{
let mut x = 0;
|| {
|| {
let y = &mut x;
&mut x; //[ast]~ ERROR cannot borrow `**x` as mutable more than once at a time
//[mir]~^ ERROR cannot borrow `**x` as mutable more than once at a time (Ast)
//[mir]~| ERROR cannot borrow `(*x)` as mutable more than once at a time (Mir)
*y = 1;
}
};
}
}