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Update NLL 3-point error message for fake reads in optimized let patterns

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This commit is contained in:
Remy Rakic 2018-09-13 17:07:34 +02:00
parent f5e310530a
commit ab236dfc86
8 changed files with 56 additions and 29 deletions
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28
src/librustc_mir/borrow_check/nll/explain_borrow/mod.rs
View file

@ -11,7 +11,7 @@
use borrow_check::borrow_set::BorrowData;
use borrow_check::nll::region_infer::Cause;
use borrow_check::{Context, MirBorrowckCtxt, WriteKind};
use rustc::mir::{Local, Location, Place, TerminatorKind};
use rustc::mir::{FakeReadCause, Local, Location, Place, StatementKind, TerminatorKind};
use rustc_errors::DiagnosticBuilder;
use rustc::ty::Region;
@ -142,7 +142,31 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
if spans.for_closure() {
"borrow later captured here by closure"
} else {
"borrow later used here"
// Check if the location represents a `FakeRead`, and adapt the error
// message to the `FakeReadCause` it is from: in particular,
// the ones inserted in optimized `let var = <expr>` patterns.
let is_fake_read_for_let = match self.mir.basic_blocks()[location.block]
.statements
.get(location.statement_index)
{
None => false,
Some(stmt) => {
if let StatementKind::FakeRead(ref cause, _) = stmt.kind {
match cause {
FakeReadCause::ForLet => true,
_ => false,
}
} else {
false
}
}
};
if is_fake_read_for_let {
"borrow later stored here"
} else {
"borrow later used here"
}
}
};
err.span_label(spans.var_or_use(), message);

5
src/test/ui/generator/borrowing.nll.stderr
View file

@ -10,6 +10,9 @@ LL | };
error[E0597]: `a` does not live long enough
--> $DIR/borrowing.rs:24:9
|
LL | let _b = {
| -- borrow later stored here
LL | let a = 3;
LL | / || {
LL | | yield &a
LL | | //~^ ERROR: `a` does not live long enough
@ -17,8 +20,6 @@ LL | | }
| |_________^ borrowed value does not live long enough
LL | };
| - `a` dropped here while still borrowed
LL | }
| - borrow later used here, when `_b` is dropped
error: aborting due to 2 previous errors

5
src/test/ui/regions/regions-steal-closure.nll.stderr
View file

@ -1,14 +1,15 @@
error[E0597]: `i` does not live long enough
--> $DIR/regions-steal-closure.rs:24:28
|
LL | let mut cl_box = {
| ---------- borrow later stored here
LL | let mut i = 3;
LL | box_it(Box::new(|| i += 1)) //~ ERROR `i` does not live long enough
| -- ^ borrowed value does not live long enough
| |
| value captured here
LL | };
| - `i` dropped here while still borrowed
LL | cl_box.cl.call_mut(());
| --------- borrow later used here
error: aborting due to previous error

12
src/test/ui/span/range-2.nll.stderr
View file

@ -1,24 +1,24 @@
error[E0597]: `a` does not live long enough
--> $DIR/range-2.rs:17:9
|
LL | let r = {
| - borrow later stored here
...
LL | &a..&b
| ^^ borrowed value does not live long enough
LL | };
| - `a` dropped here while still borrowed
...
LL | r.use_ref();
| - borrow later used here
error[E0597]: `b` does not live long enough
--> $DIR/range-2.rs:17:13
|
LL | let r = {
| - borrow later stored here
...
LL | &a..&b
| ^^ borrowed value does not live long enough
LL | };
| - `b` dropped here while still borrowed
...
LL | r.use_ref();
| - borrow later used here
error: aborting due to 2 previous errors

12
src/test/ui/span/send-is-not-static-ensures-scoping.nll.stderr
View file

@ -1,18 +1,21 @@
error[E0597]: `x` does not live long enough
--> $DIR/send-is-not-static-ensures-scoping.rs:26:17
|
LL | let bad = {
| --- borrow later stored here
LL | let x = 1;
LL | let y = &x;
| ^^ borrowed value does not live long enough
...
LL | };
| - `x` dropped here while still borrowed
LL |
LL | bad.join();
| --- borrow later used here
error[E0597]: `y` does not live long enough
--> $DIR/send-is-not-static-ensures-scoping.rs:30:22
|
LL | let bad = {
| --- borrow later stored here
...
LL | scoped(|| {
| -- value captured here
LL | let _z = y;
@ -20,9 +23,6 @@ LL | let _z = y;
...
LL | };
| - `y` dropped here while still borrowed
LL |
LL | bad.join();
| --- borrow later used here
error: aborting due to 2 previous errors

12
src/test/ui/span/send-is-not-static-std-sync-2.nll.stderr
View file

@ -1,24 +1,24 @@
error[E0597]: `x` does not live long enough
--> $DIR/send-is-not-static-std-sync-2.rs:21:20
|
LL | let lock = {
| ---- borrow later stored here
LL | let x = 1;
LL | Mutex::new(&x)
| ^^ borrowed value does not live long enough
LL | };
| - `x` dropped here while still borrowed
...
LL | let _dangling = *lock.lock().unwrap();
| ---- borrow later used here
error[E0597]: `x` does not live long enough
--> $DIR/send-is-not-static-std-sync-2.rs:31:21
|
LL | let lock = {
| ---- borrow later stored here
LL | let x = 1;
LL | RwLock::new(&x)
| ^^ borrowed value does not live long enough
LL | };
| - `x` dropped here while still borrowed
LL | //~^^ ERROR `x` does not live long enough
LL | let _dangling = *lock.read().unwrap();
| ---- borrow later used here
error[E0597]: `x` does not live long enough
--> $DIR/send-is-not-static-std-sync-2.rs:41:25

6
src/test/ui/span/wf-method-late-bound-regions.nll.stderr
View file

@ -1,13 +1,13 @@
error[E0597]: `pointer` does not live long enough
--> $DIR/wf-method-late-bound-regions.rs:30:18
|
LL | let dangling = {
| -------- borrow later stored here
LL | let pointer = Box::new(42);
LL | f2.xmute(&pointer)
| ^^^^^^^^ borrowed value does not live long enough
LL | };
| - `pointer` dropped here while still borrowed
LL | //~^^ ERROR `pointer` does not live long enough
LL | println!("{}", dangling);
| -------- borrow later used here
error: aborting due to previous error

5
src/test/ui/unboxed-closures/unboxed-closure-region.nll.stderr
View file

@ -1,14 +1,15 @@
error[E0597]: `x` does not live long enough
--> $DIR/unboxed-closure-region.rs:18:12
|
LL | let _f = {
| -- borrow later stored here
LL | let x = 0;
LL | || x //~ ERROR `x` does not live long enough
| -- ^ borrowed value does not live long enough
| |
| value captured here
LL | };
| - `x` dropped here while still borrowed
LL | _f;
| -- borrow later used here
error: aborting due to previous error