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Add union justifications to conflicting borrows.

Browse Source 
This commit adds justifications to error messages for conflicting
borrows of union fields.

Where previously an error message would say
``cannot borrow `u.b` as mutable..``, it now says
``cannot borrow `u` (via `u.b`) as mutable..``.
This commit is contained in:
David Wood 2018-12-24 20:22:25 +01:00
parent 79d8a0fcef
commit 69bded2493
No known key found for this signature in database
GPG Key ID: 01760B4F9F53F154
7 changed files with 141 additions and 127 deletions
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58
src/librustc_mir/borrow_check/error_reporting.rs
View File

@ -329,10 +329,16 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
"closure"
};
let desc_place = self.describe_place(place).unwrap_or_else(|| "_".to_owned());
let tcx = self.infcx.tcx;
let first_borrow_desc;
let (desc_place, msg_place, msg_borrow) = if issued_borrow.borrowed_place == *place {
let desc_place = self.describe_place(place).unwrap_or_else(|| "_".to_owned());
(desc_place, "".to_string(), "".to_string())
} else {
let (desc_place, msg_place) = self.describe_place_for_conflicting_borrow(place);
let (_, msg_borrow) = self.describe_place_for_conflicting_borrow(
&issued_borrow.borrowed_place
);
(desc_place, msg_place, msg_borrow)
};
let explanation = self.explain_why_borrow_contains_point(context, issued_borrow, None);
let second_borrow_desc = if explanation.is_explained() {
@ -342,6 +348,8 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
};
// FIXME: supply non-"" `opt_via` when appropriate
let tcx = self.infcx.tcx;
let first_borrow_desc;
let mut err = match (
gen_borrow_kind,
"immutable",
@ -355,12 +363,12 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
tcx.cannot_reborrow_already_borrowed(
span,
&desc_place,
"",
&msg_place,
lft,
issued_span,
"it",
rgt,
"",
&msg_borrow,
None,
Origin::Mir,
)
@ -370,12 +378,12 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
tcx.cannot_reborrow_already_borrowed(
span,
&desc_place,
"",
&msg_place,
lft,
issued_span,
"it",
rgt,
"",
&msg_borrow,
None,
Origin::Mir,
)
@ -386,9 +394,9 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
tcx.cannot_mutably_borrow_multiply(
span,
&desc_place,
"",
&msg_place,
issued_span,
"",
&msg_borrow,
None,
Origin::Mir,
)
@ -518,6 +526,36 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
err.buffer(&mut self.errors_buffer);
}
/// Returns a description of a place and an associated message for the purposes of conflicting
/// borrow diagnostics.
///
/// If the borrow is of the field `b` of a union `u`, then the return value will be
/// `("u", " (via \`u.b\`)")`. Otherwise, for some variable `a`, the return value will be
/// `("a", "")`.
pub(super) fn describe_place_for_conflicting_borrow(
&self,
place: &Place<'tcx>,
) -> (String, String) {
place.base_local()
.filter(|local| {
// Filter out non-unions.
self.mir.local_decls[*local].ty
.ty_adt_def()
.map(|adt| adt.is_union())
.unwrap_or(false)
})
.and_then(|local| {
let desc_base = self.describe_place(&Place::Local(local))
.unwrap_or_else(|| "_".to_owned());
let desc_original = self.describe_place(place)
.unwrap_or_else(|| "_".to_owned());
return Some((desc_base, format!(" (via `{}`)", desc_original)));
})
.unwrap_or_else(|| {
(self.describe_place(place).unwrap_or_else(|| "_".to_owned()), "".to_string())
})
}
/// Reports StorageDeadOrDrop of `place` conflicts with `borrow`.
///
/// This means that some data referenced by `borrow` needs to live

79
src/test/ui/borrowck/borrowck-union-borrow.ast.nll.stderr → src/test/ui/borrowck/borrowck-union-borrow.nll.stderr
View File

@ -1,132 +1,121 @@
error[E0502]: cannot borrow `u.a` as mutable because it is also borrowed as immutable
--> $DIR/borrowck-union-borrow.rs:27:23
--> $DIR/borrowck-union-borrow.rs:25:23
|
LL | let ra = &u.a;
| ---- immutable borrow occurs here
LL | let rma = &mut u.a; //[ast]~ ERROR cannot borrow `u.a` as mutable because it is also borrowed as immutable
LL | let rma = &mut u.a; //~ ERROR cannot borrow `u.a` as mutable because it is also borrowed as immutable
| ^^^^^^^^ mutable borrow occurs here
LL | //[mir]~^ ERROR cannot borrow `u.a` as mutable because it is also borrowed as immutable
LL | drop(ra);
| -- immutable borrow later used here
error[E0506]: cannot assign to `u.a` because it is borrowed
--> $DIR/borrowck-union-borrow.rs:33:13
--> $DIR/borrowck-union-borrow.rs:30:13
|
LL | let ra = &u.a;
| ---- borrow of `u.a` occurs here
LL | u.a = 1; //[ast]~ ERROR cannot assign to `u.a` because it is borrowed
LL | u.a = 1; //~ ERROR cannot assign to `u.a` because it is borrowed
| ^^^^^^^ assignment to borrowed `u.a` occurs here
LL | //[mir]~^ ERROR cannot assign to `u.a` because it is borrowed
LL | drop(ra);
| -- borrow later used here
error[E0502]: cannot borrow `u.b` as mutable because it is also borrowed as immutable
--> $DIR/borrowck-union-borrow.rs:50:23
error[E0502]: cannot borrow `u` (via `u.b`) as mutable because it is also borrowed as immutable (via `u.a`)
--> $DIR/borrowck-union-borrow.rs:46:23
|
LL | let ra = &u.a;
| ---- immutable borrow occurs here
LL | 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`)
| ^^^^^^^^ mutable borrow occurs here
LL | //[mir]~^ ERROR cannot borrow `u.b` as mutable because it is also borrowed as immutable
| ---- immutable borrow occurs here (via `u.a`)
LL | let rmb = &mut u.b; //~ ERROR cannot borrow `u` (via `u.b`) as mutable because `u` is also borrowed as immutable (via `u.a`)
| ^^^^^^^^ mutable borrow occurs here (via `u.b`)
LL | drop(ra);
| -- immutable borrow later used here
error[E0506]: cannot assign to `u.b` because it is borrowed
--> $DIR/borrowck-union-borrow.rs:56:13
--> $DIR/borrowck-union-borrow.rs:51:13
|
LL | let ra = &u.a;
| ---- borrow of `u.b` occurs here
LL | u.b = 1; //[ast]~ ERROR cannot assign to `u.b` because it is borrowed
LL | u.b = 1; //~ ERROR cannot assign to `u.b` because it is borrowed
| ^^^^^^^ assignment to borrowed `u.b` occurs here
LL | //[mir]~^ ERROR cannot assign to `u.b` because it is borrowed
LL | drop(ra);
| -- borrow later used here
error[E0502]: cannot borrow `u.a` as immutable because it is also borrowed as mutable
--> $DIR/borrowck-union-borrow.rs:63:22
--> $DIR/borrowck-union-borrow.rs:57:22
|
LL | let rma = &mut u.a;
| -------- mutable borrow occurs here
LL | let ra = &u.a; //[ast]~ ERROR cannot borrow `u.a` as immutable because it is also borrowed as mutable
LL | let ra = &u.a; //~ ERROR cannot borrow `u.a` as immutable because it is also borrowed as mutable
| ^^^^ immutable borrow occurs here
LL | //[mir]~^ ERROR cannot borrow `u.a` as immutable because it is also borrowed as mutable
LL | drop(rma);
| --- mutable borrow later used here
error[E0503]: cannot use `u.a` because it was mutably borrowed
--> $DIR/borrowck-union-borrow.rs:69:21
--> $DIR/borrowck-union-borrow.rs:62:21
|
LL | let ra = &mut u.a;
| -------- borrow of `u.a` occurs here
LL | let a = u.a; //[ast]~ ERROR cannot use `u.a` because it was mutably borrowed
LL | let a = u.a; //~ ERROR cannot use `u.a` because it was mutably borrowed
| ^^^ use of borrowed `u.a`
LL | //[mir]~^ ERROR cannot use `u.a` because it was mutably borrowed
LL | drop(ra);
| -- borrow later used here
error[E0499]: cannot borrow `u.a` as mutable more than once at a time
--> $DIR/borrowck-union-borrow.rs:75:24
--> $DIR/borrowck-union-borrow.rs:67:24
|
LL | let rma = &mut u.a;
| -------- first mutable borrow occurs here
LL | let rma2 = &mut u.a; //[ast]~ ERROR cannot borrow `u.a` as mutable more than once at a time
LL | let rma2 = &mut u.a; //~ ERROR cannot borrow `u.a` as mutable more than once at a time
| ^^^^^^^^ second mutable borrow occurs here
LL | //[mir]~^ ERROR cannot borrow `u.a` as mutable more than once at a time
LL | drop(rma);
| --- first borrow later used here
error[E0506]: cannot assign to `u.a` because it is borrowed
--> $DIR/borrowck-union-borrow.rs:81:13
--> $DIR/borrowck-union-borrow.rs:72:13
|
LL | let rma = &mut u.a;
| -------- borrow of `u.a` occurs here
LL | u.a = 1; //[ast]~ ERROR cannot assign to `u.a` because it is borrowed
LL | u.a = 1; //~ ERROR cannot assign to `u.a` because it is borrowed
| ^^^^^^^ assignment to borrowed `u.a` occurs here
LL | //[mir]~^ ERROR cannot assign to `u.a` because it is borrowed
LL | drop(rma);
| --- borrow later used here
error[E0502]: cannot borrow `u.b` as immutable because it is also borrowed as mutable
--> $DIR/borrowck-union-borrow.rs:88:22
error[E0502]: cannot borrow `u` (via `u.b`) as immutable because it is also borrowed as mutable (via `u.a`)
--> $DIR/borrowck-union-borrow.rs:78:22
|
LL | let rma = &mut u.a;
| -------- mutable borrow occurs here
LL | let rb = &u.b; //[ast]~ ERROR cannot borrow `u` (via `u.b`) as immutable because `u` is also borrowed as mutable (via `u.a`)
| ^^^^ immutable borrow occurs here
LL | //[mir]~^ ERROR cannot borrow `u.b` as immutable because it is also borrowed as mutable
| -------- mutable borrow occurs here (via `u.a`)
LL | let rb = &u.b; //~ ERROR cannot borrow `u` (via `u.b`) as immutable because `u` is also borrowed as mutable (via `u.a`)
| ^^^^ immutable borrow occurs here (via `u.b`)
LL | drop(rma);
| --- mutable borrow later used here
error[E0503]: cannot use `u.b` because it was mutably borrowed
--> $DIR/borrowck-union-borrow.rs:94:21
--> $DIR/borrowck-union-borrow.rs:83:21
|
LL | let ra = &mut u.a;
| -------- borrow of `u.a` occurs here
LL | let b = u.b; //[ast]~ ERROR cannot use `u.b` because it was mutably borrowed
LL | let b = u.b; //~ ERROR cannot use `u.b` because it was mutably borrowed
| ^^^ use of borrowed `u.a`
...
LL |
LL | drop(ra);
| -- borrow later used here
error[E0499]: cannot borrow `u.b` as mutable more than once at a time
--> $DIR/borrowck-union-borrow.rs:101:24
error[E0499]: cannot borrow `u` (via `u.b`) as mutable more than once at a time
--> $DIR/borrowck-union-borrow.rs:89:24
|
LL | let rma = &mut u.a;
| -------- first mutable borrow occurs here
LL | let rmb2 = &mut u.b; //[ast]~ ERROR cannot borrow `u` (via `u.b`) as mutable more than once at a time
| ^^^^^^^^ second mutable borrow occurs here
LL | //[mir]~^ ERROR cannot borrow `u.b` as mutable more than once at a time
| -------- first mutable borrow occurs here (via `u.a`)
LL | let rmb2 = &mut u.b; //~ ERROR cannot borrow `u` (via `u.b`) as mutable more than once at a time
| ^^^^^^^^ second mutable borrow occurs here (via `u.b`)
LL | drop(rma);
| --- first borrow later used here
error[E0506]: cannot assign to `u.b` because it is borrowed
--> $DIR/borrowck-union-borrow.rs:107:13
--> $DIR/borrowck-union-borrow.rs:94:13
|
LL | let rma = &mut u.a;
| -------- borrow of `u.b` occurs here
LL | u.b = 1; //[ast]~ ERROR cannot assign to `u.b` because it is borrowed
LL | u.b = 1; //~ ERROR cannot assign to `u.b` because it is borrowed
| ^^^^^^^ assignment to borrowed `u.b` occurs here
LL | //[mir]~^ ERROR cannot assign to `u.b` because it is borrowed
LL | drop(rma);
| --- borrow later used here

38
src/test/ui/borrowck/borrowck-union-borrow.rs
View File

@ -1,6 +1,4 @@
// ignore-tidy-linelength
// revisions: ast mir
//[mir]compile-flags: -Z borrowck=mir
#[derive(Clone, Copy)]
union U {
@ -24,14 +22,12 @@ fn main() {
}
{
let ra = &u.a;
let rma = &mut u.a; //[ast]~ ERROR cannot borrow `u.a` as mutable because it is also borrowed as immutable
//[mir]~^ ERROR cannot borrow `u.a` as mutable because it is also borrowed as immutable
let rma = &mut u.a; //~ ERROR cannot borrow `u.a` as mutable because it is also borrowed as immutable
drop(ra);
}
{
let ra = &u.a;
u.a = 1; //[ast]~ ERROR cannot assign to `u.a` because it is borrowed
//[mir]~^ ERROR cannot assign to `u.a` because it is borrowed
u.a = 1; //~ ERROR cannot assign to `u.a` because it is borrowed
drop(ra);
}
// Imm borrow, other field
@ -47,65 +43,55 @@ 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`)
//[mir]~^ ERROR cannot borrow `u.b` as mutable because it is also borrowed as immutable
let rmb = &mut u.b; //~ ERROR cannot borrow `u` (via `u.b`) as mutable because `u` is also borrowed as immutable (via `u.a`)
drop(ra);
}
{
let ra = &u.a;
u.b = 1; //[ast]~ ERROR cannot assign to `u.b` because it is borrowed
//[mir]~^ ERROR cannot assign to `u.b` because it is borrowed
u.b = 1; //~ ERROR cannot assign to `u.b` because it is borrowed
drop(ra);
}
// Mut borrow, same field
{
let rma = &mut u.a;
let ra = &u.a; //[ast]~ ERROR cannot borrow `u.a` as immutable because it is also borrowed as mutable
//[mir]~^ ERROR cannot borrow `u.a` as immutable because it is also borrowed as mutable
let ra = &u.a; //~ ERROR cannot borrow `u.a` as immutable because it is also borrowed as mutable
drop(rma);
}
{
let ra = &mut u.a;
let a = u.a; //[ast]~ ERROR cannot use `u.a` because it was mutably borrowed
//[mir]~^ ERROR cannot use `u.a` because it was mutably borrowed
let a = u.a; //~ ERROR cannot use `u.a` because it was mutably borrowed
drop(ra);
}
{
let rma = &mut u.a;
let rma2 = &mut u.a; //[ast]~ ERROR cannot borrow `u.a` as mutable more than once at a time
//[mir]~^ ERROR cannot borrow `u.a` as mutable more than once at a time
let rma2 = &mut u.a; //~ ERROR cannot borrow `u.a` as mutable more than once at a time
drop(rma);
}
{
let rma = &mut u.a;
u.a = 1; //[ast]~ ERROR cannot assign to `u.a` because it is borrowed
//[mir]~^ ERROR cannot assign to `u.a` because it is borrowed
u.a = 1; //~ ERROR cannot assign to `u.a` because it is borrowed
drop(rma);
}
// Mut borrow, other field
{
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`)
//[mir]~^ ERROR cannot borrow `u.b` as immutable because it is also borrowed as mutable
let rb = &u.b; //~ ERROR cannot borrow `u` (via `u.b`) as immutable because `u` is also borrowed as mutable (via `u.a`)
drop(rma);
}
{
let ra = &mut u.a;
let b = u.b; //[ast]~ ERROR cannot use `u.b` because it was mutably borrowed
//[mir]~^ ERROR cannot use `u.b` because it was mutably borrowed
let b = u.b; //~ ERROR cannot use `u.b` because it was mutably borrowed
drop(ra);
}
{
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
//[mir]~^ ERROR cannot borrow `u.b` as mutable more than once at a time
let rmb2 = &mut u.b; //~ ERROR cannot borrow `u` (via `u.b`) as mutable more than once at a time
drop(rma);
}
{
let rma = &mut u.a;
u.b = 1; //[ast]~ ERROR cannot assign to `u.b` because it is borrowed
//[mir]~^ ERROR cannot assign to `u.b` because it is borrowed
u.b = 1; //~ ERROR cannot assign to `u.b` because it is borrowed
drop(rma);
}
}

60
src/test/ui/borrowck/borrowck-union-borrow.ast.stderr → src/test/ui/borrowck/borrowck-union-borrow.stderr
View File

@ -1,115 +1,115 @@
error[E0502]: cannot borrow `u.a` as mutable because it is also borrowed as immutable
--> $DIR/borrowck-union-borrow.rs:27:28
--> $DIR/borrowck-union-borrow.rs:25:28
|
LL | let ra = &u.a;
| --- immutable borrow occurs here
LL | let rma = &mut u.a; //[ast]~ ERROR cannot borrow `u.a` as mutable because it is also borrowed as immutable
LL | let rma = &mut u.a; //~ ERROR cannot borrow `u.a` as mutable because it is also borrowed as immutable
| ^^^ mutable borrow occurs here
...
LL | drop(ra);
LL | }
| - immutable borrow ends here
error[E0506]: cannot assign to `u.a` because it is borrowed
--> $DIR/borrowck-union-borrow.rs:33:13
--> $DIR/borrowck-union-borrow.rs:30:13
|
LL | let ra = &u.a;
| --- borrow of `u.a` occurs here
LL | u.a = 1; //[ast]~ ERROR cannot assign to `u.a` because it is borrowed
LL | u.a = 1; //~ ERROR cannot assign to `u.a` because it is borrowed
| ^^^^^^^ assignment to borrowed `u.a` occurs here
error[E0502]: cannot borrow `u` (via `u.b`) as mutable because `u` is also borrowed as immutable (via `u.a`)
--> $DIR/borrowck-union-borrow.rs:50:28
--> $DIR/borrowck-union-borrow.rs:46:28
|
LL | let ra = &u.a;
| --- immutable borrow occurs here (via `u.a`)
LL | 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`)
LL | let rmb = &mut u.b; //~ ERROR cannot borrow `u` (via `u.b`) as mutable because `u` is also borrowed as immutable (via `u.a`)
| ^^^ mutable borrow occurs here (via `u.b`)
...
LL | drop(ra);
LL | }
| - immutable borrow ends here
error[E0506]: cannot assign to `u.b` because it is borrowed
--> $DIR/borrowck-union-borrow.rs:56:13
--> $DIR/borrowck-union-borrow.rs:51:13
|
LL | let ra = &u.a;
| --- borrow of `u.b` occurs here
LL | u.b = 1; //[ast]~ ERROR cannot assign to `u.b` because it is borrowed
LL | u.b = 1; //~ ERROR cannot assign to `u.b` because it is borrowed
| ^^^^^^^ assignment to borrowed `u.b` occurs here
error[E0502]: cannot borrow `u.a` as immutable because it is also borrowed as mutable
--> $DIR/borrowck-union-borrow.rs:63:23
--> $DIR/borrowck-union-borrow.rs:57:23
|
LL | let rma = &mut u.a;
| --- mutable borrow occurs here
LL | let ra = &u.a; //[ast]~ ERROR cannot borrow `u.a` as immutable because it is also borrowed as mutable
LL | let ra = &u.a; //~ ERROR cannot borrow `u.a` as immutable because it is also borrowed as mutable
| ^^^ immutable borrow occurs here
...
LL | drop(rma);
LL | }
| - mutable borrow ends here
error[E0503]: cannot use `u.a` because it was mutably borrowed
--> $DIR/borrowck-union-borrow.rs:69:17
--> $DIR/borrowck-union-borrow.rs:62:17
|
LL | let ra = &mut u.a;
| --- borrow of `u.a` occurs here
LL | let a = u.a; //[ast]~ ERROR cannot use `u.a` because it was mutably borrowed
LL | let a = u.a; //~ ERROR cannot use `u.a` because it was mutably borrowed
| ^ use of borrowed `u.a`
error[E0499]: cannot borrow `u.a` as mutable more than once at a time
--> $DIR/borrowck-union-borrow.rs:75:29
--> $DIR/borrowck-union-borrow.rs:67:29
|
LL | let rma = &mut u.a;
| --- first mutable borrow occurs here
LL | let rma2 = &mut u.a; //[ast]~ ERROR cannot borrow `u.a` as mutable more than once at a time
LL | let rma2 = &mut u.a; //~ ERROR cannot borrow `u.a` as mutable more than once at a time
| ^^^ second mutable borrow occurs here
...
LL | drop(rma);
LL | }
| - first borrow ends here
error[E0506]: cannot assign to `u.a` because it is borrowed
--> $DIR/borrowck-union-borrow.rs:81:13
--> $DIR/borrowck-union-borrow.rs:72:13
|
LL | let rma = &mut u.a;
| --- borrow of `u.a` occurs here
LL | u.a = 1; //[ast]~ ERROR cannot assign to `u.a` because it is borrowed
LL | u.a = 1; //~ ERROR cannot assign to `u.a` because it is borrowed
| ^^^^^^^ assignment to borrowed `u.a` occurs here
error[E0502]: cannot borrow `u` (via `u.b`) as immutable because `u` is also borrowed as mutable (via `u.a`)
--> $DIR/borrowck-union-borrow.rs:88:23
--> $DIR/borrowck-union-borrow.rs:78:23
|
LL | let rma = &mut u.a;
| --- mutable borrow occurs here (via `u.a`)
LL | let rb = &u.b; //[ast]~ ERROR cannot borrow `u` (via `u.b`) as immutable because `u` is also borrowed as mutable (via `u.a`)
LL | let rb = &u.b; //~ ERROR cannot borrow `u` (via `u.b`) as immutable because `u` is also borrowed as mutable (via `u.a`)
| ^^^ immutable borrow occurs here (via `u.b`)
...
LL | drop(rma);
LL | }
| - mutable borrow ends here
error[E0503]: cannot use `u.b` because it was mutably borrowed
--> $DIR/borrowck-union-borrow.rs:94:17
--> $DIR/borrowck-union-borrow.rs:83:17
|
LL | let ra = &mut u.a;
| --- borrow of `u.a` occurs here
LL | let b = u.b; //[ast]~ ERROR cannot use `u.b` because it was mutably borrowed
LL | let b = u.b; //~ ERROR cannot use `u.b` because it was mutably borrowed
| ^ use of borrowed `u.a`
error[E0499]: cannot borrow `u` (via `u.b`) as mutable more than once at a time
--> $DIR/borrowck-union-borrow.rs:101:29
--> $DIR/borrowck-union-borrow.rs:89:29
|
LL | let rma = &mut u.a;
| --- first mutable borrow occurs here (via `u.a`)
LL | let rmb2 = &mut u.b; //[ast]~ ERROR cannot borrow `u` (via `u.b`) as mutable more than once at a time
LL | let rmb2 = &mut u.b; //~ ERROR cannot borrow `u` (via `u.b`) as mutable more than once at a time
| ^^^ second mutable borrow occurs here (via `u.b`)
...
LL | drop(rma);
LL | }
| - first borrow ends here
error[E0506]: cannot assign to `u.b` because it is borrowed
--> $DIR/borrowck-union-borrow.rs:107:13
--> $DIR/borrowck-union-borrow.rs:94:13
|
LL | let rma = &mut u.a;
| --- borrow of `u.b` occurs here
LL | u.b = 1; //[ast]~ ERROR cannot assign to `u.b` because it is borrowed
LL | u.b = 1; //~ ERROR cannot assign to `u.b` because it is borrowed
| ^^^^^^^ assignment to borrowed `u.b` occurs here
error: aborting due to 12 previous errors

5
src/test/ui/issues/issue-45157.rs
View File

@ -1,6 +1,8 @@
#![allow(unused)]
#![feature(nll)]
// ignore-tidy-linelength
#[derive(Clone, Copy, Default)]
struct S {
a: u8,
@ -25,8 +27,7 @@ fn main() {
*mref = 22;
let nref = &u.z.c;
//~^ ERROR cannot borrow `u.z.c` as immutable because it is also borrowed as mutable [E0502]
//~^ ERROR cannot borrow `u` (via `u.z.c`) as immutable because it is also borrowed as mutable (via `u.s.a`) [E0502]
println!("{} {}", mref, nref)
}
}

10
src/test/ui/issues/issue-45157.stderr
View File

@ -1,12 +1,12 @@
error[E0502]: cannot borrow `u.z.c` as immutable because it is also borrowed as mutable
--> $DIR/issue-45157.rs:27:20
error[E0502]: cannot borrow `u` (via `u.z.c`) as immutable because it is also borrowed as mutable (via `u.s.a`)
--> $DIR/issue-45157.rs:29:20
|
LL | let mref = &mut u.s.a;
| ---------- mutable borrow occurs here
| ---------- mutable borrow occurs here (via `u.s.a`)
...
LL | let nref = &u.z.c;
| ^^^^^^ immutable borrow occurs here
LL | //~^ ERROR cannot borrow `u.z.c` as immutable because it is also borrowed as mutable [E0502]
| ^^^^^^ immutable borrow occurs here (via `u.z.c`)
LL | //~^ ERROR cannot borrow `u` (via `u.z.c`) as immutable because it is also borrowed as mutable (via `u.s.a`) [E0502]
LL | println!("{} {}", mref, nref)
| ---- mutable borrow later used here

18
src/test/ui/union/union-borrow-move-parent-sibling.nll.stderr
View File

@ -1,10 +1,10 @@
error[E0502]: cannot borrow `u.y` as immutable because it is also borrowed as mutable
error[E0502]: cannot borrow `u` (via `u.y`) as immutable because it is also borrowed as mutable (via `u.x.0`)
--> $DIR/union-borrow-move-parent-sibling.rs:15:13
|
LL | let a = &mut u.x.0;
| ---------- mutable borrow occurs here
| ---------- mutable borrow occurs here (via `u.x.0`)
LL | let b = &u.y; //~ ERROR cannot borrow `u.y`
| ^^^^ immutable borrow occurs here
| ^^^^ immutable borrow occurs here (via `u.y`)
LL | use_borrow(a);
| - mutable borrow later used here
@ -18,13 +18,13 @@ LL | let b = u.y; //~ ERROR use of moved value: `u.y`
|
= note: move occurs because `u` has type `U`, which does not implement the `Copy` trait
error[E0502]: cannot borrow `u.y` as immutable because it is also borrowed as mutable
error[E0502]: cannot borrow `u` (via `u.y`) as immutable because it is also borrowed as mutable (via `u.x.0.0`)
--> $DIR/union-borrow-move-parent-sibling.rs:28:13
|
LL | let a = &mut (u.x.0).0;
| -------------- mutable borrow occurs here
| -------------- mutable borrow occurs here (via `u.x.0.0`)
LL | let b = &u.y; //~ ERROR cannot borrow `u.y`
| ^^^^ immutable borrow occurs here
| ^^^^ immutable borrow occurs here (via `u.y`)
LL | use_borrow(a);
| - mutable borrow later used here
@ -38,13 +38,13 @@ LL | let b = u.y; //~ ERROR use of moved value: `u.y`
|
= note: move occurs because `u` has type `U`, which does not implement the `Copy` trait
error[E0502]: cannot borrow `u.x` as immutable because it is also borrowed as mutable
error[E0502]: cannot borrow `u` (via `u.x`) as immutable because it is also borrowed as mutable (via `*u.y`)
--> $DIR/union-borrow-move-parent-sibling.rs:41:13
|
LL | let a = &mut *u.y;
| --------- mutable borrow occurs here
| --------- mutable borrow occurs here (via `*u.y`)
LL | let b = &u.x; //~ ERROR cannot borrow `u` (via `u.x`)
| ^^^^ immutable borrow occurs here
| ^^^^ immutable borrow occurs here (via `u.x`)
LL | use_borrow(a);
| - mutable borrow later used here