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Do not ICE when suggesting dereferencing closure arg

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Account for `for` lifetimes when constructing closure to see if dereferencing the return value would be valid.

Fix #125634, fix #124563.
This commit is contained in:
Esteban Küber 2024-06-24 01:11:56 +00:00
parent 33422e72c8
commit a2298a6f19
8 changed files with 119 additions and 8 deletions
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6
compiler/rustc_borrowck/src/diagnostics/region_errors.rs
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@ -1152,7 +1152,9 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
// Get the arguments for the found method, only specifying that `Self` is the receiver type.
let Some(possible_rcvr_ty) = typeck_results.node_type_opt(rcvr.hir_id) else { return };
let args = GenericArgs::for_item(tcx, method_def_id, |param, _| {
if param.index == 0 {
if let ty::GenericParamDefKind::Lifetime = param.kind {
tcx.lifetimes.re_erased.into()
} else if param.index == 0 && param.name == kw::SelfUpper {
possible_rcvr_ty.into()
} else if param.index == closure_param.index {
closure_ty.into()
@ -1169,7 +1171,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
Obligation::misc(tcx, span, self.mir_def_id(), self.param_env, pred)
}));
if ocx.select_all_or_error().is_empty() {
if ocx.select_all_or_error().is_empty() && count > 0 {
diag.span_suggestion_verbose(
tcx.hir().body(*body).value.peel_blocks().span.shrink_to_lo(),
"dereference the return value",

19
tests/ui/regions/account-for-lifetimes-in-closure-suggestion.rs Normal file
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@ -0,0 +1,19 @@
// #125634
struct Thing;
// Invariant in 'a, Covariant in 'b
struct TwoThings<'a, 'b>(*mut &'a (), &'b mut ());
impl Thing {
fn enter_scope<'a>(self, _scope: impl for<'b> FnOnce(TwoThings<'a, 'b>)) {}
}
fn foo() {
Thing.enter_scope(|ctx| {
SameLifetime(ctx); //~ ERROR lifetime may not live long enough
});
}
struct SameLifetime<'a>(TwoThings<'a, 'a>);
fn main() {}

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

11
tests/crashes/124563.rs → tests/ui/regions/lifetime-not-long-enough-suggestion-regression-test-124563.rs
View File

@ -1,5 +1,4 @@
//@ known-bug: rust-lang/rust#124563
// #124563
use std::marker::PhantomData;
pub trait Trait {}
@ -17,11 +16,11 @@ where
T: Trait,
{
type Trait = T;
type Bar = BarImpl<'a, 'b, T>;
type Bar = BarImpl<'a, 'b, T>; //~ ERROR lifetime bound not satisfied
fn foo(&mut self) {
self.enter_scope(|ctx| {
BarImpl(ctx);
self.enter_scope(|ctx| { //~ ERROR lifetime may not live long enough
BarImpl(ctx); //~ ERROR lifetime may not live long enough
});
}
}
@ -44,3 +43,5 @@ where
{
type Foo = FooImpl<'a, 'b, T>;
}
fn main() {}

49
tests/ui/regions/lifetime-not-long-enough-suggestion-regression-test-124563.stderr Normal file
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@ -0,0 +1,49 @@
error[E0478]: lifetime bound not satisfied
--> $DIR/lifetime-not-long-enough-suggestion-regression-test-124563.rs:19:16
|
LL | type Bar = BarImpl<'a, 'b, T>;
| ^^^^^^^^^^^^^^^^^^
|
note: lifetime parameter instantiated with the lifetime `'a` as defined here
--> $DIR/lifetime-not-long-enough-suggestion-regression-test-124563.rs:14:6
|
LL | impl<'a, 'b, T> Foo for FooImpl<'a, 'b, T>
| ^^
note: but lifetime parameter must outlive the lifetime `'b` as defined here
--> $DIR/lifetime-not-long-enough-suggestion-regression-test-124563.rs:14:10
|
LL | impl<'a, 'b, T> Foo for FooImpl<'a, 'b, T>
| ^^
error: lifetime may not live long enough
--> $DIR/lifetime-not-long-enough-suggestion-regression-test-124563.rs:23:21
|
LL | self.enter_scope(|ctx| {
| ---
| |
| has type `&'1 mut FooImpl<'_, '_, T>`
| has type `&mut FooImpl<'2, '_, T>`
LL | BarImpl(ctx);
| ^^^ this usage requires that `'1` must outlive `'2`
error: lifetime may not live long enough
--> $DIR/lifetime-not-long-enough-suggestion-regression-test-124563.rs:22:9
|
LL | impl<'a, 'b, T> Foo for FooImpl<'a, 'b, T>
| -- -- lifetime `'b` defined here
| |
| lifetime `'a` defined here
...
LL | / self.enter_scope(|ctx| {
LL | | BarImpl(ctx);
LL | | });
| |__________^ argument requires that `'a` must outlive `'b`
|
= help: consider adding the following bound: `'a: 'b`
= note: requirement occurs because of a mutable reference to `FooImpl<'_, '_, T>`
= note: mutable references are invariant over their type parameter
= help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance
error: aborting due to 3 previous errors
For more information about this error, try `rustc --explain E0478`.

17
tests/ui/regions/regions-escape-method.fixed Normal file
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@ -0,0 +1,17 @@
// Test a method call where the parameter `B` would (illegally) be
// inferred to a region bound in the method argument. If this program
// were accepted, then the closure passed to `s.f` could escape its
// argument.
//@ run-rustfix
struct S;
impl S {
fn f<B, F>(&self, _: F) where F: FnOnce(&i32) -> B {
}
}
fn main() {
let s = S;
s.f(|p| *p) //~ ERROR lifetime may not live long enough
}

1
tests/ui/regions/regions-escape-method.rs
View File

@ -2,6 +2,7 @@
// inferred to a region bound in the method argument. If this program
// were accepted, then the closure passed to `s.f` could escape its
// argument.
//@ run-rustfix
struct S;

7
tests/ui/regions/regions-escape-method.stderr
View File

@ -1,11 +1,16 @@
error: lifetime may not live long enough
--> $DIR/regions-escape-method.rs:15:13
--> $DIR/regions-escape-method.rs:16:13
|
LL | s.f(|p| p)
| -- ^ returning this value requires that `'1` must outlive `'2`
| ||
| |return type of closure is &'2 i32
| has type `&'1 i32`
|
help: dereference the return value
|
LL | s.f(|p| *p)
| +
error: aborting due to 1 previous error