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matthiaskrgrmatthiaskrgr
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Rollup merge of #126884 - estebank:issue-125634, r=Nadrieril
Do not ICE when suggesting dereferencing closure arg Account for `for` lifetimes when constructing closure to see if dereferencing the return value would be valid. Fix #125634, fix #124563.
2 parents 52e6f9c + a2298a6 commit 175756f

8 files changed

+119
-8
lines changed

‎compiler/rustc_borrowck/src/diagnostics/region_errors.rs

+4-2
Original file line numberDiff line numberDiff line change
@@ -1151,7 +1151,9 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
11511151
// Get the arguments for the found method, only specifying that `Self` is the receiver type.
11521152
let Some(possible_rcvr_ty) = typeck_results.node_type_opt(rcvr.hir_id) else { return };
11531153
let args = GenericArgs::for_item(tcx, method_def_id, |param, _| {
1154-
if param.index == 0 {
1154+
if let ty::GenericParamDefKind::Lifetime = param.kind {
1155+
tcx.lifetimes.re_erased.into()
1156+
} else if param.index == 0 && param.name == kw::SelfUpper {
11551157
possible_rcvr_ty.into()
11561158
} else if param.index == closure_param.index {
11571159
closure_ty.into()
@@ -1168,7 +1170,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
11681170
Obligation::misc(tcx, span, self.mir_def_id(), self.param_env, pred)
11691171
}));
11701172

1171-
if ocx.select_all_or_error().is_empty() {
1173+
if ocx.select_all_or_error().is_empty() && count > 0 {
11721174
diag.span_suggestion_verbose(
11731175
tcx.hir().body(*body).value.peel_blocks().span.shrink_to_lo(),
11741176
"dereference the return value",

‎tests/ui/regions/account-for-lifetimes-in-closure-suggestion.rs

+19
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,19 @@
1+
// #125634
2+
struct Thing;
3+
4+
// Invariant in 'a, Covariant in 'b
5+
struct TwoThings<'a, 'b>(*mut &'a (), &'b mut ());
6+
7+
impl Thing {
8+
fn enter_scope<'a>(self, _scope: impl for<'b> FnOnce(TwoThings<'a, 'b>)) {}
9+
}
10+
11+
fn foo() {
12+
Thing.enter_scope(|ctx| {
13+
SameLifetime(ctx); //~ ERROR lifetime may not live long enough
14+
});
15+
}
16+
17+
struct SameLifetime<'a>(TwoThings<'a, 'a>);
18+
19+
fn main() {}

‎tests/ui/regions/account-for-lifetimes-in-closure-suggestion.stderr

+17
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,17 @@
1+
error: lifetime may not live long enough
2+
--> $DIR/account-for-lifetimes-in-closure-suggestion.rs:13:22
3+
|
4+
LL | Thing.enter_scope(|ctx| {
5+
| ---
6+
| |
7+
| has type `TwoThings<'_, '1>`
8+
| has type `TwoThings<'2, '_>`
9+
LL | SameLifetime(ctx);
10+
| ^^^ this usage requires that `'1` must outlive `'2`
11+
|
12+
= note: requirement occurs because of the type `TwoThings<'_, '_>`, which makes the generic argument `'_` invariant
13+
= note: the struct `TwoThings<'a, 'b>` is invariant over the parameter `'a`
14+
= help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance
15+
16+
error: aborting due to 1 previous error
17+

‎tests/crashes/124563.rs ‎tests/ui/regions/lifetime-not-long-enough-suggestion-regression-test-124563.rs

+6-5
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,4 @@
1-
//@ known-bug: rust-lang/rust#124563
2-
1+
// #124563
32
use std::marker::PhantomData;
43

54
pub trait Trait {}
@@ -17,11 +16,11 @@ where
1716
T: Trait,
1817
{
1918
type Trait = T;
20-
type Bar = BarImpl<'a, 'b, T>;
19+
type Bar = BarImpl<'a, 'b, T>; //~ ERROR lifetime bound not satisfied
2120

2221
fn foo(&mut self) {
23-
self.enter_scope(|ctx| {
24-
BarImpl(ctx);
22+
self.enter_scope(|ctx| { //~ ERROR lifetime may not live long enough
23+
BarImpl(ctx); //~ ERROR lifetime may not live long enough
2524
});
2625
}
2726
}
@@ -44,3 +43,5 @@ where
4443
{
4544
type Foo = FooImpl<'a, 'b, T>;
4645
}
46+
47+
fn main() {}

‎tests/ui/regions/lifetime-not-long-enough-suggestion-regression-test-124563.stderr

+49
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,49 @@
1+
error[E0478]: lifetime bound not satisfied
2+
--> $DIR/lifetime-not-long-enough-suggestion-regression-test-124563.rs:19:16
3+
|
4+
LL | type Bar = BarImpl<'a, 'b, T>;
5+
| ^^^^^^^^^^^^^^^^^^
6+
|
7+
note: lifetime parameter instantiated with the lifetime `'a` as defined here
8+
--> $DIR/lifetime-not-long-enough-suggestion-regression-test-124563.rs:14:6
9+
|
10+
LL | impl<'a, 'b, T> Foo for FooImpl<'a, 'b, T>
11+
| ^^
12+
note: but lifetime parameter must outlive the lifetime `'b` as defined here
13+
--> $DIR/lifetime-not-long-enough-suggestion-regression-test-124563.rs:14:10
14+
|
15+
LL | impl<'a, 'b, T> Foo for FooImpl<'a, 'b, T>
16+
| ^^
17+
18+
error: lifetime may not live long enough
19+
--> $DIR/lifetime-not-long-enough-suggestion-regression-test-124563.rs:23:21
20+
|
21+
LL | self.enter_scope(|ctx| {
22+
| ---
23+
| |
24+
| has type `&'1 mut FooImpl<'_, '_, T>`
25+
| has type `&mut FooImpl<'2, '_, T>`
26+
LL | BarImpl(ctx);
27+
| ^^^ this usage requires that `'1` must outlive `'2`
28+
29+
error: lifetime may not live long enough
30+
--> $DIR/lifetime-not-long-enough-suggestion-regression-test-124563.rs:22:9
31+
|
32+
LL | impl<'a, 'b, T> Foo for FooImpl<'a, 'b, T>
33+
| -- -- lifetime `'b` defined here
34+
| |
35+
| lifetime `'a` defined here
36+
...
37+
LL | / self.enter_scope(|ctx| {
38+
LL | | BarImpl(ctx);
39+
LL | | });
40+
| |__________^ argument requires that `'a` must outlive `'b`
41+
|
42+
= help: consider adding the following bound: `'a: 'b`
43+
= note: requirement occurs because of a mutable reference to `FooImpl<'_, '_, T>`
44+
= note: mutable references are invariant over their type parameter
45+
= help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance
46+
47+
error: aborting due to 3 previous errors
48+
49+
For more information about this error, try `rustc --explain E0478`.

‎tests/ui/regions/regions-escape-method.fixed

+17
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,17 @@
1+
// Test a method call where the parameter `B` would (illegally) be
2+
// inferred to a region bound in the method argument. If this program
3+
// were accepted, then the closure passed to `s.f` could escape its
4+
// argument.
5+
//@ run-rustfix
6+
7+
struct S;
8+
9+
impl S {
10+
fn f<B, F>(&self, _: F) where F: FnOnce(&i32) -> B {
11+
}
12+
}
13+
14+
fn main() {
15+
let s = S;
16+
s.f(|p| *p) //~ ERROR lifetime may not live long enough
17+
}

‎tests/ui/regions/regions-escape-method.rs

+1
Original file line numberDiff line numberDiff line change
@@ -2,6 +2,7 @@
22
// inferred to a region bound in the method argument. If this program
33
// were accepted, then the closure passed to `s.f` could escape its
44
// argument.
5+
//@ run-rustfix
56

67
struct S;
78

‎tests/ui/regions/regions-escape-method.stderr

+6-1
Original file line numberDiff line numberDiff line change
@@ -1,11 +1,16 @@
11
error: lifetime may not live long enough
2-
--> $DIR/regions-escape-method.rs:15:13
2+
--> $DIR/regions-escape-method.rs:16:13
33
|
44
LL | s.f(|p| p)
55
| -- ^ returning this value requires that `'1` must outlive `'2`
66
| ||
77
| |return type of closure is &'2 i32
88
| has type `&'1 i32`
9+
|
10+
help: dereference the return value
11+
|
12+
LL | s.f(|p| *p)
13+
| +
914

1015
error: aborting due to 1 previous error
1116

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