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mir-borrowck: Implement end-user output for field of field projection

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This commit is contained in:
Basile Desloges 2017-10-06 17:25:41 +02:00
parent f35c4e3aa1
commit ce3b2e779e
2 changed files with 25 additions and 5 deletions
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7
src/librustc_mir/borrow_check.rs
View file

@ -1125,11 +1125,6 @@ impl<'c, 'b, 'a: 'b+'c, 'gcx, 'tcx: 'a> MirBorrowckCtxt<'c, 'b, 'a, 'gcx, 'tcx>
match proj.elem {
ProjectionElem::Deref =>
self.describe_field(&proj.base, field_index),
ProjectionElem::Field(..) => {
debug!("End-user description not implemented for field of projection {:?}",
proj);
format!("<field>{}", field_index)
},
ProjectionElem::Index(..) => {
debug!("End-user description not implemented for field of projection {:?}",
proj);
@ -1142,6 +1137,8 @@ impl<'c, 'b, 'a: 'b+'c, 'gcx, 'tcx: 'a> MirBorrowckCtxt<'c, 'b, 'a, 'gcx, 'tcx>
},
ProjectionElem::Downcast(def, variant_index) =>
format!("{}", def.variants[variant_index].fields[field_index].name),
ProjectionElem::Field(_, field_type) =>
self.describe_field_from_ty(&field_type, field_index),
ProjectionElem::Subslice { .. } => {
debug!("End-user description not implemented for field of projection {:?}",
proj);

23
src/test/compile-fail/borrowck/borrowck-describe-lvalue.rs
View file

@ -253,4 +253,27 @@ fn main() {
println!("e.bx: {:?}", bx),
}
}
// Field in field
{
struct F { x: u32, y: u32 };
struct S { x: F, y: (u32, u32), };
let mut s = S { x: F { x: 1, y: 2}, y: (999, 998) };
let _s = &mut s;
match s {
S { y: (ref y0, _), .. } =>
//[ast]~^ ERROR cannot borrow `s.y.0` as immutable because `s` is also borrowed as mutable
//[mir]~^^ ERROR cannot borrow `s.y.0` as immutable because `s` is also borrowed as mutable (Ast)
//[mir]~| ERROR cannot borrow `s.y.0` as immutable because it is also borrowed as mutable (Mir)
println!("y0: {:?}", y0),
_ => panic!("other case"),
}
match s {
S { x: F { y: ref x0, .. }, .. } =>
//[ast]~^ ERROR cannot borrow `s.x.y` as immutable because `s` is also borrowed as mutable
//[mir]~^^ ERROR cannot borrow `s.x.y` as immutable because `s` is also borrowed as mutable (Ast)
//[mir]~| ERROR cannot borrow `s.x.y` as immutable because it is also borrowed as mutable (Mir)
println!("x0: {:?}", x0),
_ => panic!("other case"),
}
}
}