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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.
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@ -1152,7 +1152,9 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
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// Get the arguments for the found method, only specifying that `Self` is the receiver type.
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let Some(possible_rcvr_ty) = typeck_results.node_type_opt(rcvr.hir_id) else { return };
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let args = GenericArgs::for_item(tcx, method_def_id, |param, _| {
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if param.index == 0 {
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if let ty::GenericParamDefKind::Lifetime = param.kind {
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tcx.lifetimes.re_erased.into()
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} else if param.index == 0 && param.name == kw::SelfUpper {
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possible_rcvr_ty.into()
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} else if param.index == closure_param.index {
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closure_ty.into()
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@ -1169,7 +1171,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
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Obligation::misc(tcx, span, self.mir_def_id(), self.param_env, pred)
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}));
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if ocx.select_all_or_error().is_empty() {
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if ocx.select_all_or_error().is_empty() && count > 0 {
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diag.span_suggestion_verbose(
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tcx.hir().body(*body).value.peel_blocks().span.shrink_to_lo(),
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"dereference the return value",
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@ -0,0 +1,19 @@
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// #125634
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struct Thing;
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// Invariant in 'a, Covariant in 'b
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struct TwoThings<'a, 'b>(*mut &'a (), &'b mut ());
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impl Thing {
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fn enter_scope<'a>(self, _scope: impl for<'b> FnOnce(TwoThings<'a, 'b>)) {}
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}
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fn foo() {
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Thing.enter_scope(|ctx| {
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SameLifetime(ctx); //~ ERROR lifetime may not live long enough
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});
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}
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struct SameLifetime<'a>(TwoThings<'a, 'a>);
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fn main() {}
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@ -0,0 +1,17 @@
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error: lifetime may not live long enough
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--> $DIR/account-for-lifetimes-in-closure-suggestion.rs:13:22
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LL | Thing.enter_scope(|ctx| {
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| ---
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| |
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| has type `TwoThings<'_, '1>`
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| has type `TwoThings<'2, '_>`
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LL | SameLifetime(ctx);
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| ^^^ this usage requires that `'1` must outlive `'2`
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= note: requirement occurs because of the type `TwoThings<'_, '_>`, which makes the generic argument `'_` invariant
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= note: the struct `TwoThings<'a, 'b>` is invariant over the parameter `'a`
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= help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance
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error: aborting due to 1 previous error
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@ -1,5 +1,4 @@
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//@ known-bug: rust-lang/rust#124563
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// #124563
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use std::marker::PhantomData;
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pub trait Trait {}
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@ -17,11 +16,11 @@ where
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T: Trait,
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{
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type Trait = T;
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type Bar = BarImpl<'a, 'b, T>;
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type Bar = BarImpl<'a, 'b, T>; //~ ERROR lifetime bound not satisfied
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fn foo(&mut self) {
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self.enter_scope(|ctx| {
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BarImpl(ctx);
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self.enter_scope(|ctx| { //~ ERROR lifetime may not live long enough
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BarImpl(ctx); //~ ERROR lifetime may not live long enough
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});
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}
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}
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@ -44,3 +43,5 @@ where
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{
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type Foo = FooImpl<'a, 'b, T>;
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}
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fn main() {}
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@ -0,0 +1,49 @@
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error[E0478]: lifetime bound not satisfied
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--> $DIR/lifetime-not-long-enough-suggestion-regression-test-124563.rs:19:16
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LL | type Bar = BarImpl<'a, 'b, T>;
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| ^^^^^^^^^^^^^^^^^^
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note: lifetime parameter instantiated with the lifetime `'a` as defined here
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--> $DIR/lifetime-not-long-enough-suggestion-regression-test-124563.rs:14:6
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LL | impl<'a, 'b, T> Foo for FooImpl<'a, 'b, T>
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| ^^
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note: but lifetime parameter must outlive the lifetime `'b` as defined here
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--> $DIR/lifetime-not-long-enough-suggestion-regression-test-124563.rs:14:10
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LL | impl<'a, 'b, T> Foo for FooImpl<'a, 'b, T>
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| ^^
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error: lifetime may not live long enough
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--> $DIR/lifetime-not-long-enough-suggestion-regression-test-124563.rs:23:21
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LL | self.enter_scope(|ctx| {
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| ---
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| |
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| has type `&'1 mut FooImpl<'_, '_, T>`
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| has type `&mut FooImpl<'2, '_, T>`
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LL | BarImpl(ctx);
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| ^^^ this usage requires that `'1` must outlive `'2`
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error: lifetime may not live long enough
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--> $DIR/lifetime-not-long-enough-suggestion-regression-test-124563.rs:22:9
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LL | impl<'a, 'b, T> Foo for FooImpl<'a, 'b, T>
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| -- -- lifetime `'b` defined here
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| |
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| lifetime `'a` defined here
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...
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LL | / self.enter_scope(|ctx| {
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LL | | BarImpl(ctx);
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LL | | });
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| |__________^ argument requires that `'a` must outlive `'b`
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= help: consider adding the following bound: `'a: 'b`
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= note: requirement occurs because of a mutable reference to `FooImpl<'_, '_, T>`
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= note: mutable references are invariant over their type parameter
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= help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance
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error: aborting due to 3 previous errors
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For more information about this error, try `rustc --explain E0478`.
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17
tests/ui/regions/regions-escape-method.fixed
Normal file
17
tests/ui/regions/regions-escape-method.fixed
Normal file
@ -0,0 +1,17 @@
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// Test a method call where the parameter `B` would (illegally) be
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// inferred to a region bound in the method argument. If this program
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// were accepted, then the closure passed to `s.f` could escape its
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// argument.
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//@ run-rustfix
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struct S;
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impl S {
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fn f<B, F>(&self, _: F) where F: FnOnce(&i32) -> B {
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}
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}
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fn main() {
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let s = S;
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s.f(|p| *p) //~ ERROR lifetime may not live long enough
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}
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@ -2,6 +2,7 @@
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// inferred to a region bound in the method argument. If this program
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// were accepted, then the closure passed to `s.f` could escape its
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// argument.
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//@ run-rustfix
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struct S;
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@ -1,11 +1,16 @@
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error: lifetime may not live long enough
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--> $DIR/regions-escape-method.rs:15:13
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--> $DIR/regions-escape-method.rs:16:13
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LL | s.f(|p| p)
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| -- ^ returning this value requires that `'1` must outlive `'2`
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| ||
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| |return type of closure is &'2 i32
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| has type `&'1 i32`
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help: dereference the return value
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LL | s.f(|p| *p)
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| +
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error: aborting due to 1 previous error
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