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matthewjaspermatthewjasper
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Handle regions equivalent to 'static in non_local_bounds
`non_local_bounds` would only find non local bounds that strictly bound a given region, but it's possible that a local region is equated to 'static when showing a type referencing a locally bound lifetime, such as `dyn Any + 'a` in the tests added, is well-formed. In this case we should return 'static.
1 parent e5fefc3 commit 73464a9

7 files changed

+185
-15
lines changed

‎compiler/rustc_borrowck/src/type_check/free_region_relations.rs

+2-1
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@@ -133,7 +133,8 @@ impl UniversalRegionRelations<'_> {
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assert!(self.universal_regions.is_universal_region(fr0));
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let mut external_parents = vec![];
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let mut queue = vec![fr0];
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let mut queue = vec![relation.scc_representative(fr0)];
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// Keep expanding `fr` into its parents until we reach
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// non-local regions.

‎compiler/rustc_data_structures/src/transitive_relation.rs

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@@ -354,6 +354,20 @@ impl<T: Eq + Hash + Copy> TransitiveRelation<T> {
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.collect()
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}
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/// Given an element A, elements B with the lowest index such that `A R B`
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/// and `B R A`, or `A` if no such element exists.
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pub fn scc_representative(&self, a: T) -> T {
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match self.index(a) {
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Some(a_i) => self.with_closure(|closure| {
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closure
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.iter(a_i.0)
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.find(|i| closure.contains(*i, a_i.0))
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.map_or(a, |i| self.elements[i])
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}),
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None => a,
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}
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}
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fn with_closure<OP, R>(&self, op: OP) -> R
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where
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OP: FnOnce(&BitMatrix<usize, usize>) -> R,

‎tests/crashes/122704.rs

-14
This file was deleted.

‎tests/ui/borrowck/unconstrained-closure-lifetime-generic.rs

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@@ -0,0 +1,22 @@
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// Regression test for #122704
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use std::any::Any;
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pub struct Foo {
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bar: Box<dyn for<'a> Fn(&'a usize) -> Box<dyn Any + 'a>>,
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}
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impl Foo {
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pub fn ack<I>(&mut self, f: impl for<'a> Fn(&'a usize) -> Box<I>) {
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self.bar = Box::new(|baz| Box::new(f(baz)));
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//~^ ERROR the parameter type `impl for<'a> Fn(&'a usize) -> Box<I>` may not live long enough
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//~| ERROR the parameter type `impl for<'a> Fn(&'a usize) -> Box<I>` may not live long enough
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//~| ERROR the parameter type `impl for<'a> Fn(&'a usize) -> Box<I>` may not live long enough
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//~| ERROR the parameter type `impl for<'a> Fn(&'a usize) -> Box<I>` may not live long enough
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//~| ERROR the parameter type `I` may not live long enough
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//~| ERROR the parameter type `I` may not live long enough
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//~| ERROR the parameter type `I` may not live long enough
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//~| ERROR `f` does not live long enough
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}
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}
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fn main() {}

‎tests/ui/borrowck/unconstrained-closure-lifetime-generic.stderr

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@@ -0,0 +1,119 @@
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error[E0310]: the parameter type `impl for<'a> Fn(&'a usize) -> Box<I>` may not live long enough
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--> $DIR/unconstrained-closure-lifetime-generic.rs:10:9
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|
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LL | self.bar = Box::new(|baz| Box::new(f(baz)));
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| ^^^^^^^^
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| |
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| the parameter type `impl for<'a> Fn(&'a usize) -> Box<I>` must be valid for the static lifetime...
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| ...so that the type `impl for<'a> Fn(&'a usize) -> Box<I>` will meet its required lifetime bounds
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|
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help: consider adding an explicit lifetime bound
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|
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LL | pub fn ack<I>(&mut self, f: impl for<'a> Fn(&'a usize) -> Box<I> + 'static) {
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| +++++++++
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error[E0310]: the parameter type `impl for<'a> Fn(&'a usize) -> Box<I>` may not live long enough
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--> $DIR/unconstrained-closure-lifetime-generic.rs:10:9
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|
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LL | self.bar = Box::new(|baz| Box::new(f(baz)));
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| ^^^^^^^^
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| |
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| the parameter type `impl for<'a> Fn(&'a usize) -> Box<I>` must be valid for the static lifetime...
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| ...so that the type `impl for<'a> Fn(&'a usize) -> Box<I>` will meet its required lifetime bounds
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|
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= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
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help: consider adding an explicit lifetime bound
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|
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LL | pub fn ack<I>(&mut self, f: impl for<'a> Fn(&'a usize) -> Box<I> + 'static) {
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| +++++++++
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error[E0310]: the parameter type `impl for<'a> Fn(&'a usize) -> Box<I>` may not live long enough
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--> $DIR/unconstrained-closure-lifetime-generic.rs:10:20
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|
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LL | self.bar = Box::new(|baz| Box::new(f(baz)));
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| ^^^^^^^^
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| |
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| the parameter type `impl for<'a> Fn(&'a usize) -> Box<I>` must be valid for the static lifetime...
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| ...so that the type `impl for<'a> Fn(&'a usize) -> Box<I>` will meet its required lifetime bounds
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|
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help: consider adding an explicit lifetime bound
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|
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LL | pub fn ack<I>(&mut self, f: impl for<'a> Fn(&'a usize) -> Box<I> + 'static) {
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| +++++++++
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error[E0310]: the parameter type `impl for<'a> Fn(&'a usize) -> Box<I>` may not live long enough
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--> $DIR/unconstrained-closure-lifetime-generic.rs:10:20
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|
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LL | self.bar = Box::new(|baz| Box::new(f(baz)));
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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| |
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| the parameter type `impl for<'a> Fn(&'a usize) -> Box<I>` must be valid for the static lifetime...
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| ...so that the type `impl for<'a> Fn(&'a usize) -> Box<I>` will meet its required lifetime bounds
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|
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help: consider adding an explicit lifetime bound
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|
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LL | pub fn ack<I>(&mut self, f: impl for<'a> Fn(&'a usize) -> Box<I> + 'static) {
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| +++++++++
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error[E0310]: the parameter type `I` may not live long enough
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--> $DIR/unconstrained-closure-lifetime-generic.rs:10:35
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|
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LL | self.bar = Box::new(|baz| Box::new(f(baz)));
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| ^^^^^^^^^^^^^^^^
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| |
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| the parameter type `I` must be valid for the static lifetime...
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| ...so that the type `I` will meet its required lifetime bounds
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|
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help: consider adding an explicit lifetime bound
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|
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LL | pub fn ack<I: 'static>(&mut self, f: impl for<'a> Fn(&'a usize) -> Box<I>) {
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| +++++++++
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error[E0310]: the parameter type `I` may not live long enough
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--> $DIR/unconstrained-closure-lifetime-generic.rs:10:35
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|
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LL | self.bar = Box::new(|baz| Box::new(f(baz)));
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| ^^^^^^^^^^^^^^^^
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| |
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| the parameter type `I` must be valid for the static lifetime...
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| ...so that the type `I` will meet its required lifetime bounds
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|
81+
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
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help: consider adding an explicit lifetime bound
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|
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LL | pub fn ack<I: 'static>(&mut self, f: impl for<'a> Fn(&'a usize) -> Box<I>) {
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| +++++++++
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error[E0311]: the parameter type `I` may not live long enough
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--> $DIR/unconstrained-closure-lifetime-generic.rs:10:35
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|
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LL | pub fn ack<I>(&mut self, f: impl for<'a> Fn(&'a usize) -> Box<I>) {
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| --------- the parameter type `I` must be valid for the anonymous lifetime defined here...
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LL | self.bar = Box::new(|baz| Box::new(f(baz)));
93+
| ^^^^^^^^^^^^^^^^ ...so that the type `I` will meet its required lifetime bounds
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|
95+
help: consider adding an explicit lifetime bound
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|
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LL | pub fn ack<'a, I: 'a>(&'a mut self, f: impl for<'a> Fn(&'a usize) -> Box<I>) {
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| +++ ++++ ++
99+
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error[E0597]: `f` does not live long enough
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--> $DIR/unconstrained-closure-lifetime-generic.rs:10:44
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|
103+
LL | pub fn ack<I>(&mut self, f: impl for<'a> Fn(&'a usize) -> Box<I>) {
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| - binding `f` declared here
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LL | self.bar = Box::new(|baz| Box::new(f(baz)));
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| -------- ----- ^ borrowed value does not live long enough
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| | |
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| | value captured here
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| coercion requires that `f` is borrowed for `'static`
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...
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LL | }
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| - `f` dropped here while still borrowed
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|
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= note: due to object lifetime defaults, `Box<dyn for<'a> Fn(&'a usize) -> Box<(dyn Any + 'a)>>` actually means `Box<(dyn for<'a> Fn(&'a usize) -> Box<(dyn Any + 'a)> + 'static)>`
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error: aborting due to 8 previous errors
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Some errors have detailed explanations: E0310, E0311, E0597.
119+
For more information about an error, try `rustc --explain E0310`.

‎tests/ui/borrowck/unconstrained-closure-lifetime-trait-object.rs

+11
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@@ -0,0 +1,11 @@
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// Regression test for #139004
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use std::any::Any;
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type B = Box<dyn for<'a> Fn(&(dyn Any + 'a)) -> Box<dyn Any + 'a>>;
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fn foo<E>() -> B {
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Box::new(|e| Box::new(e.is::<E>()))
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//~^ ERROR the parameter type `E` may not live long enough
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}
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fn main() {}

‎tests/ui/borrowck/unconstrained-closure-lifetime-trait-object.stderr

+17
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@@ -0,0 +1,17 @@
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error[E0310]: the parameter type `E` may not live long enough
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--> $DIR/unconstrained-closure-lifetime-trait-object.rs:7:29
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|
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LL | Box::new(|e| Box::new(e.is::<E>()))
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| ^^
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| |
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| the parameter type `E` must be valid for the static lifetime...
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| ...so that the type `E` will meet its required lifetime bounds
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|
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help: consider adding an explicit lifetime bound
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|
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LL | fn foo<E: 'static>() -> B {
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| +++++++++
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error: aborting due to 1 previous error
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For more information about this error, try `rustc --explain E0310`.

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