Rollup merge of #122100 - compiler-errors:better-capture, r=oli-obk

Better comment for implicit captures in RPITIT

Improve the error message for implicit captures. Also always set E0657.

r? oli-obk

compiler/rustc_error_codes/src/error_codes/E0657.md

@@ -1,57 +1,26 @@
-A lifetime bound on a trait implementation was captured at an incorrect place.
+An `impl Trait` captured a higher-ranked lifetime, which is not supported.
+
+Currently, `impl Trait` types are only allowed to capture lifetimes from
+their parent items, and not from any `for<'a>` binders in scope.
 
 Erroneous code example:
 
 ```compile_fail,E0657
-trait Id<T> {}
+trait BorrowInto<'a> {
-trait Lt<'a> {}
+    type Target;
 
-impl<'a> Lt<'a> for () {}
+    fn borrow_into(&'a self) -> Self::Target;
-impl<T> Id<T> for T {}
-
-fn free_fn_capture_hrtb_in_impl_trait()
-    -> Box<for<'a> Id<impl Lt<'a>>> // error!
-{
-    Box::new(())
 }
 
-struct Foo;
+impl<'a> BorrowInto<'a> for () {
-impl Foo {
+    type Target = &'a ();
-    fn impl_fn_capture_hrtb_in_impl_trait()
+
-        -> Box<for<'a> Id<impl Lt<'a>>> // error!
+    fn borrow_into(&'a self) -> Self::Target {
-    {
+        self
-        Box::new(())
     }
 }
-```
 
-Here, you have used the inappropriate lifetime in the `impl Trait`,
+fn opaque() -> impl for<'a> BorrowInto<'a, Target = impl Sized + 'a> {
-The `impl Trait` can only capture lifetimes bound at the fn or impl
+    ()
-level.
-
-To fix this we have to define the lifetime at the function or impl
-level and use that lifetime in the `impl Trait`. For example you can
-define the lifetime at the function:
-
-```
-trait Id<T> {}
-trait Lt<'a> {}
-
-impl<'a> Lt<'a> for () {}
-impl<T> Id<T> for T {}
-
-fn free_fn_capture_hrtb_in_impl_trait<'b>()
-    -> Box<for<'a> Id<impl Lt<'b>>> // ok!
-{
-    Box::new(())
-}
-
-struct Foo;
-impl Foo {
-    fn impl_fn_capture_hrtb_in_impl_trait<'b>()
-        -> Box<for<'a> Id<impl Lt<'b>>> // ok!
-    {
-        Box::new(())
-    }
 }
 ```

compiler/rustc_hir_analysis/messages.ftl

@@ -312,6 +312,10 @@ hir_analysis_only_current_traits_primitive = only traits defined in the current
 
 hir_analysis_only_current_traits_ty = `{$ty}` is not defined in the current crate
 
+hir_analysis_opaque_captures_higher_ranked_lifetime = `impl Trait` cannot capture {$bad_place}
+    .label = `impl Trait` implicitly captures all lifetimes in scope
+    .note = lifetime declared here
+
 hir_analysis_paren_sugar_attribute = the `#[rustc_paren_sugar]` attribute is a temporary means of controlling which traits can use parenthetical notation
     .help = add `#![feature(unboxed_closures)]` to the crate attributes to use it
 

compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs

@@ -9,7 +9,6 @@
 use core::ops::ControlFlow;
 use rustc_ast::visit::walk_list;
 use rustc_data_structures::fx::{FxHashSet, FxIndexMap, FxIndexSet};
-use rustc_errors::{codes::*, struct_span_code_err};
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::LocalDefId;
@@ -669,34 +668,47 @@ impl<'a, 'tcx> Visitor<'tcx> for BoundVarContext<'a, 'tcx> {
                     // and ban them. Type variables instantiated inside binders aren't
                     // well-supported at the moment, so this doesn't work.
                     // In the future, this should be fixed and this error should be removed.
-                    let def = self.map.defs.get(&lifetime.hir_id).cloned();
+                    let def = self.map.defs.get(&lifetime.hir_id).copied();
-                    let Some(ResolvedArg::LateBound(_, _, def_id)) = def else { continue };
+                    let Some(ResolvedArg::LateBound(_, _, lifetime_def_id)) = def else { continue };
-                    let Some(def_id) = def_id.as_local() else { continue };
+                    let Some(lifetime_def_id) = lifetime_def_id.as_local() else { continue };
-                    let hir_id = self.tcx.local_def_id_to_hir_id(def_id);
+                    let lifetime_hir_id = self.tcx.local_def_id_to_hir_id(lifetime_def_id);
-                    // Ensure that the parent of the def is an item, not HRTB
+
-                    let parent_id = self.tcx.parent_hir_id(hir_id);
+                    let bad_place = match self.tcx.hir_node(self.tcx.parent_hir_id(lifetime_hir_id))
-                    if !parent_id.is_owner() {
-                        struct_span_code_err!(
-                            self.tcx.dcx(),
-                            lifetime.ident.span,
-                            E0657,
-                            "`impl Trait` can only capture lifetimes bound at the fn or impl level"
-                        )
-                        .emit();
-                        self.uninsert_lifetime_on_error(lifetime, def.unwrap());
-                    }
-                    if let hir::Node::Item(hir::Item {
-                        kind: hir::ItemKind::OpaqueTy { .. }, ..
-                    }) = self.tcx.hir_node(parent_id)
                     {
-                        self.tcx.dcx().struct_span_err(
+                        // Opaques do not declare their own lifetimes, so if a lifetime comes from an opaque
-                            lifetime.ident.span,
+                        // it must be a reified late-bound lifetime from a trait goal.
-                            "higher kinded lifetime bounds on nested opaque types are not supported yet",
+                        hir::Node::Item(hir::Item {
-                        )
+                            kind: hir::ItemKind::OpaqueTy { .. }, ..
-                        .with_span_note(self.tcx.def_span(def_id), "lifetime declared here")
+                        }) => "higher-ranked lifetime from outer `impl Trait`",
-                        .emit();
+                        // Other items are fine.
-                        self.uninsert_lifetime_on_error(lifetime, def.unwrap());
+                        hir::Node::Item(_) | hir::Node::TraitItem(_) | hir::Node::ImplItem(_) => {
-                    }
+                            continue;
+                        }
+                        hir::Node::Ty(hir::Ty { kind: hir::TyKind::BareFn(_), .. }) => {
+                            "higher-ranked lifetime from function pointer"
+                        }
+                        hir::Node::Ty(hir::Ty { kind: hir::TyKind::TraitObject(..), .. }) => {
+                            "higher-ranked lifetime from `dyn` type"
+                        }
+                        _ => "higher-ranked lifetime",
+                    };
+
+                    let (span, label) = if lifetime.ident.span == self.tcx.def_span(lifetime_def_id)
+                    {
+                        let opaque_span = self.tcx.def_span(item_id.owner_id);
+                        (opaque_span, Some(opaque_span))
+                    } else {
+                        (lifetime.ident.span, None)
+                    };
+
+                    // Ensure that the parent of the def is an item, not HRTB
+                    self.tcx.dcx().emit_err(errors::OpaqueCapturesHigherRankedLifetime {
+                        span,
+                        label,
+                        decl_span: self.tcx.def_span(lifetime_def_id),
+                        bad_place,
+                    });
+                    self.uninsert_lifetime_on_error(lifetime, def.unwrap());
                 }
             }
             _ => intravisit::walk_ty(self, ty),

compiler/rustc_hir_analysis/src/errors.rs

@@ -1607,3 +1607,15 @@ pub struct UnnamedFieldsReprFieldDefined {
     #[primary_span]
     pub span: Span,
 }
+
+#[derive(Diagnostic)]
+#[diag(hir_analysis_opaque_captures_higher_ranked_lifetime, code = E0657)]
+pub struct OpaqueCapturesHigherRankedLifetime {
+    #[primary_span]
+    pub span: Span,
+    #[label]
+    pub label: Option<Span>,
+    #[note]
+    pub decl_span: Span,
+    pub bad_place: &'static str,
+}

tests/ui/error-codes/E0657.rs

@@ -8,7 +8,7 @@ impl<T> Id<T> for T {}
 
 fn free_fn_capture_hrtb_in_impl_trait()
     -> Box<for<'a> Id<impl Lt<'a>>>
-        //~^ ERROR `impl Trait` can only capture lifetimes bound at the fn or impl level [E0657]
+        //~^ ERROR `impl Trait` cannot capture higher-ranked lifetime from `dyn` type
 {
     Box::new(())
 }
@@ -17,7 +17,7 @@ struct Foo;
 impl Foo {
     fn impl_fn_capture_hrtb_in_impl_trait()
         -> Box<for<'a> Id<impl Lt<'a>>>
-            //~^ ERROR `impl Trait` can only capture lifetimes bound at the fn or impl level
+            //~^ ERROR `impl Trait` cannot capture higher-ranked lifetime from `dyn` type
     {
         Box::new(())
     }

tests/ui/error-codes/E0657.stderr

@@ -1,14 +1,26 @@
-error[E0657]: `impl Trait` can only capture lifetimes bound at the fn or impl level
+error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from `dyn` type
   --> $DIR/E0657.rs:10:31
    |
 LL |     -> Box<for<'a> Id<impl Lt<'a>>>
    |                               ^^
+   |
+note: lifetime declared here
+  --> $DIR/E0657.rs:10:16
+   |
+LL |     -> Box<for<'a> Id<impl Lt<'a>>>
+   |                ^^
 
-error[E0657]: `impl Trait` can only capture lifetimes bound at the fn or impl level
+error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from `dyn` type
   --> $DIR/E0657.rs:19:35
    |
 LL |         -> Box<for<'a> Id<impl Lt<'a>>>
    |                                   ^^
+   |
+note: lifetime declared here
+  --> $DIR/E0657.rs:19:20
+   |
+LL |         -> Box<for<'a> Id<impl Lt<'a>>>
+   |                    ^^
 
 error: aborting due to 2 previous errors
 

tests/ui/impl-trait/impl-fn-hrtb-bounds.rs

@@ -2,19 +2,19 @@
 use std::fmt::Debug;
 
 fn a() -> impl Fn(&u8) -> (impl Debug + '_) {
-    //~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
+    //~^ ERROR `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
     |x| x
     //~^ ERROR lifetime may not live long enough
 }
 
 fn b() -> impl for<'a> Fn(&'a u8) -> (impl Debug + 'a) {
-    //~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
+    //~^ ERROR `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
     |x| x
     //~^ ERROR lifetime may not live long enough
 }
 
 fn c() -> impl for<'a> Fn(&'a u8) -> (impl Debug + '_) {
-    //~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
+    //~^ ERROR `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
     |x| x
     //~^ ERROR lifetime may not live long enough
 }

tests/ui/impl-trait/impl-fn-hrtb-bounds.stderr

@@ -10,7 +10,7 @@ help: consider using the `'static` lifetime, but this is uncommon unless you're
 LL | fn d() -> impl Fn() -> (impl Debug + 'static) {
    |                                      ~~~~~~~
 
-error: higher kinded lifetime bounds on nested opaque types are not supported yet
+error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
   --> $DIR/impl-fn-hrtb-bounds.rs:4:41
    |
 LL | fn a() -> impl Fn(&u8) -> (impl Debug + '_) {
@@ -31,7 +31,7 @@ LL |     |x| x
    |      |return type of closure is impl Debug + '2
    |      has type `&'1 u8`
 
-error: higher kinded lifetime bounds on nested opaque types are not supported yet
+error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
   --> $DIR/impl-fn-hrtb-bounds.rs:10:52
    |
 LL | fn b() -> impl for<'a> Fn(&'a u8) -> (impl Debug + 'a) {
@@ -52,7 +52,7 @@ LL |     |x| x
    |      |return type of closure is impl Debug + '2
    |      has type `&'1 u8`
 
-error: higher kinded lifetime bounds on nested opaque types are not supported yet
+error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
   --> $DIR/impl-fn-hrtb-bounds.rs:16:52
    |
 LL | fn c() -> impl for<'a> Fn(&'a u8) -> (impl Debug + '_) {
@@ -75,4 +75,5 @@ LL |     |x| x
 
 error: aborting due to 7 previous errors
 
-For more information about this error, try `rustc --explain E0106`.
+Some errors have detailed explanations: E0106, E0657.
+For more information about an error, try `rustc --explain E0106`.

tests/ui/impl-trait/impl-fn-parsing-ambiguities.rs

@@ -3,7 +3,7 @@ use std::fmt::Debug;
 
 fn a() -> impl Fn(&u8) -> impl Debug + '_ {
     //~^ ERROR ambiguous `+` in a type
-    //~| ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
+    //~| ERROR cannot capture higher-ranked lifetime from outer `impl Trait`
     |x| x
     //~^ ERROR lifetime may not live long enough
 }

tests/ui/impl-trait/impl-fn-parsing-ambiguities.stderr

@@ -10,7 +10,7 @@ error: ambiguous `+` in a type
 LL | fn b() -> impl Fn() -> impl Debug + Send {
    |                        ^^^^^^^^^^^^^^^^^ help: use parentheses to disambiguate: `(impl Debug + Send)`
 
-error: higher kinded lifetime bounds on nested opaque types are not supported yet
+error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
   --> $DIR/impl-fn-parsing-ambiguities.rs:4:40
    |
 LL | fn a() -> impl Fn(&u8) -> impl Debug + '_ {
@@ -33,3 +33,4 @@ LL |     |x| x
 
 error: aborting due to 4 previous errors
 
+For more information about this error, try `rustc --explain E0657`.

tests/ui/impl-trait/implicit-capture-late.stderr

@@ -1,4 +1,10 @@
-error[E0657]: `impl Trait` can only capture lifetimes bound at the fn or impl level
+error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from `dyn` type
+  --> $DIR/implicit-capture-late.rs:10:55
+   |
+LL | fn foo(x: Vec<i32>) -> Box<dyn for<'a> Deref<Target = impl ?Sized>> {
+   |                                                       ^^^^^^^^^^^ `impl Trait` implicitly captures all lifetimes in scope
+   |
+note: lifetime declared here
   --> $DIR/implicit-capture-late.rs:10:36
    |
 LL | fn foo(x: Vec<i32>) -> Box<dyn for<'a> Deref<Target = impl ?Sized>> {

tests/ui/impl-trait/issues/issue-54895.rs

@@ -13,7 +13,7 @@ impl<'a> Trait<'a> for X {
 }
 
 fn f() -> impl for<'a> Trait<'a, Out = impl Sized + 'a> {
-    //~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
+    //~^ ERROR `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
     X(())
 }
 

tests/ui/impl-trait/issues/issue-54895.stderr

@@ -1,4 +1,4 @@
-error: higher kinded lifetime bounds on nested opaque types are not supported yet
+error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
   --> $DIR/issue-54895.rs:15:53
    |
 LL | fn f() -> impl for<'a> Trait<'a, Out = impl Sized + 'a> {
@@ -12,3 +12,4 @@ LL | fn f() -> impl for<'a> Trait<'a, Out = impl Sized + 'a> {
 
 error: aborting due to 1 previous error
 
+For more information about this error, try `rustc --explain E0657`.

tests/ui/impl-trait/issues/issue-67830.rs

@@ -19,7 +19,7 @@ where
 
 struct A;
 fn test() -> impl for<'a> MyFn<&'a A, Output=impl Iterator + 'a> {
-    //~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
+    //~^ ERROR `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
     Wrap(|a| Some(a).into_iter())
     //~^ ERROR implementation of `FnOnce` is not general enough
     //~| ERROR implementation of `FnOnce` is not general enough

tests/ui/impl-trait/issues/issue-67830.stderr

@@ -1,4 +1,4 @@
-error: higher kinded lifetime bounds on nested opaque types are not supported yet
+error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
   --> $DIR/issue-67830.rs:21:62
    |
 LL | fn test() -> impl for<'a> MyFn<&'a A, Output=impl Iterator + 'a> {
@@ -31,3 +31,4 @@ LL |     Wrap(|a| Some(a).into_iter())
 
 error: aborting due to 3 previous errors
 
+For more information about this error, try `rustc --explain E0657`.

tests/ui/impl-trait/issues/issue-88236-2.rs

@@ -13,17 +13,17 @@ impl<'a> Hrtb<'a> for &'a () {
 }
 
 fn make_impl() -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {}
-//~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
+//~^ ERROR `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
 
 fn make_weird_impl<'b>(x: &'b ()) -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {
-    //~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
+    //~^ ERROR `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
     &()
     //~^ ERROR implementation of `Hrtb` is not general enough
     //~| ERROR implementation of `Hrtb` is not general enough
 }
 
 fn make_bad_impl<'b>(x: &'b ()) -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {
-    //~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
+    //~^ ERROR `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
     x
     //~^ ERROR implementation of `Hrtb` is not general enough
     //~| ERROR implementation of `Hrtb` is not general enough

tests/ui/impl-trait/issues/issue-88236-2.stderr

@@ -1,4 +1,4 @@
-error: higher kinded lifetime bounds on nested opaque types are not supported yet
+error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
   --> $DIR/issue-88236-2.rs:15:61
    |
 LL | fn make_impl() -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {}
@@ -10,7 +10,7 @@ note: lifetime declared here
 LL | fn make_impl() -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {}
    |                            ^^
 
-error: higher kinded lifetime bounds on nested opaque types are not supported yet
+error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
   --> $DIR/issue-88236-2.rs:18:80
    |
 LL | fn make_weird_impl<'b>(x: &'b ()) -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {
@@ -40,7 +40,7 @@ LL |     &()
    = note: `Hrtb<'a>` would have to be implemented for the type `&()`
    = note: ...but `Hrtb<'0>` is actually implemented for the type `&'0 ()`, for some specific lifetime `'0`
 
-error: higher kinded lifetime bounds on nested opaque types are not supported yet
+error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
   --> $DIR/issue-88236-2.rs:25:78
    |
 LL | fn make_bad_impl<'b>(x: &'b ()) -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {
@@ -90,3 +90,4 @@ LL |     x
 
 error: aborting due to 8 previous errors
 
+For more information about this error, try `rustc --explain E0657`.

tests/ui/impl-trait/issues/issue-88236.rs

@@ -13,6 +13,6 @@ impl<'a> Hrtb<'a> for &'a () {
 }
 
 fn make_impl() -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {}
-//~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
+//~^ ERROR `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
 
 fn main() {}

tests/ui/impl-trait/issues/issue-88236.stderr

@@ -1,4 +1,4 @@
-error: higher kinded lifetime bounds on nested opaque types are not supported yet
+error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
   --> $DIR/issue-88236.rs:15:61
    |
 LL | fn make_impl() -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {}
@@ -12,3 +12,4 @@ LL | fn make_impl() -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {}
 
 error: aborting due to 1 previous error
 
+For more information about this error, try `rustc --explain E0657`.

tests/ui/impl-trait/nested-rpit-hrtb.rs

@@ -23,18 +23,18 @@ impl Qux<'_> for () {}
 
 // This is not supported.
 fn one_hrtb_outlives() -> impl for<'a> Foo<'a, Assoc = impl Sized + 'a> {}
-//~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
+//~^ ERROR `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
 
 // This is not supported.
 fn one_hrtb_trait_param() -> impl for<'a> Foo<'a, Assoc = impl Qux<'a>> {}
-//~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
+//~^ ERROR `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
 
 fn one_hrtb_outlives_uses() -> impl for<'a> Bar<'a, Assoc = impl Sized + 'a> {}
-//~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
+//~^ ERROR `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
 //~| ERROR implementation of `Bar` is not general enough
 
 fn one_hrtb_trait_param_uses() -> impl for<'a> Bar<'a, Assoc = impl Qux<'a>> {}
-//~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
+//~^ ERROR `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
 //~| ERROR: the trait bound `for<'a> &'a (): Qux<'_>` is not satisfied
 
 // This should resolve.

tests/ui/impl-trait/nested-rpit-hrtb.stderr

@@ -29,7 +29,7 @@ help: consider introducing lifetime `'b` here
 LL | fn two_htrb_outlives_uses<'b>() -> impl for<'a> Bar<'a, Assoc = impl for<'b> Sized + 'b> {}
    |                          ++++
 
-error: higher kinded lifetime bounds on nested opaque types are not supported yet
+error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
   --> $DIR/nested-rpit-hrtb.rs:25:69
    |
 LL | fn one_hrtb_outlives() -> impl for<'a> Foo<'a, Assoc = impl Sized + 'a> {}
@@ -41,7 +41,7 @@ note: lifetime declared here
 LL | fn one_hrtb_outlives() -> impl for<'a> Foo<'a, Assoc = impl Sized + 'a> {}
    |                                    ^^
 
-error: higher kinded lifetime bounds on nested opaque types are not supported yet
+error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
   --> $DIR/nested-rpit-hrtb.rs:29:68
    |
 LL | fn one_hrtb_trait_param() -> impl for<'a> Foo<'a, Assoc = impl Qux<'a>> {}
@@ -53,7 +53,7 @@ note: lifetime declared here
 LL | fn one_hrtb_trait_param() -> impl for<'a> Foo<'a, Assoc = impl Qux<'a>> {}
    |                                       ^^
 
-error: higher kinded lifetime bounds on nested opaque types are not supported yet
+error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
   --> $DIR/nested-rpit-hrtb.rs:32:74
    |
 LL | fn one_hrtb_outlives_uses() -> impl for<'a> Bar<'a, Assoc = impl Sized + 'a> {}
@@ -74,7 +74,7 @@ LL | fn one_hrtb_outlives_uses() -> impl for<'a> Bar<'a, Assoc = impl Sized + 'a
    = note: `()` must implement `Bar<'a>`
    = note: ...but it actually implements `Bar<'0>`, for some specific lifetime `'0`
 
-error: higher kinded lifetime bounds on nested opaque types are not supported yet
+error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
   --> $DIR/nested-rpit-hrtb.rs:36:73
    |
 LL | fn one_hrtb_trait_param_uses() -> impl for<'a> Bar<'a, Assoc = impl Qux<'a>> {}
@@ -133,5 +133,5 @@ LL | fn two_htrb_outlives_uses() -> impl for<'a> Bar<'a, Assoc = impl for<'b> Si
 
 error: aborting due to 12 previous errors
 
-Some errors have detailed explanations: E0261, E0277.
+Some errors have detailed explanations: E0261, E0277, E0657.
 For more information about an error, try `rustc --explain E0261`.

tests/ui/type-alias-impl-trait/escaping-bound-var.rs

@@ -7,7 +7,7 @@ pub trait Trait<'a> {
 trait Test<'a> {}
 
 pub type Foo = impl for<'a> Trait<'a, Assoc = impl Test<'a>>;
-//~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
+//~^ ERROR `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
 
 impl Trait<'_> for () {
     type Assoc = ();

tests/ui/type-alias-impl-trait/escaping-bound-var.stderr

@@ -1,8 +1,8 @@
-error: higher kinded lifetime bounds on nested opaque types are not supported yet
+error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
-  --> $DIR/escaping-bound-var.rs:9:25
+  --> $DIR/escaping-bound-var.rs:9:47
    |
 LL | pub type Foo = impl for<'a> Trait<'a, Assoc = impl Test<'a>>;
-   |                         ^^
+   |                                               ^^^^^^^^^^^^^ `impl Trait` implicitly captures all lifetimes in scope
    |
 note: lifetime declared here
   --> $DIR/escaping-bound-var.rs:9:25
@@ -12,3 +12,4 @@ LL | pub type Foo = impl for<'a> Trait<'a, Assoc = impl Test<'a>>;
 
 error: aborting due to 1 previous error
 
+For more information about this error, try `rustc --explain E0657`.

tests/ui/type-alias-impl-trait/variance.rs

@@ -12,11 +12,11 @@ type CapturedEarly<'a> = impl Sized + Captures<'a>; //~ [*, o]
 //~^ ERROR: unconstrained opaque type
 
 type NotCapturedLate<'a> = dyn for<'b> Iterator<Item = impl Sized>; //~ [*, o, o]
-//~^ ERROR `impl Trait` can only capture lifetimes bound at the fn or impl level
+//~^ ERROR `impl Trait` cannot capture higher-ranked lifetime from `dyn` type
 //~| ERROR: unconstrained opaque type
 
 type Captured<'a> = dyn for<'b> Iterator<Item = impl Sized + Captures<'a>>; //~ [*, o, o]
-//~^ ERROR `impl Trait` can only capture lifetimes bound at the fn or impl level
+//~^ ERROR `impl Trait` cannot capture higher-ranked lifetime from `dyn` type
 //~| ERROR: unconstrained opaque type
 
 type Bar<'a, 'b: 'b, T> = impl Sized; //~ ERROR [*, *, o, o, o]

tests/ui/type-alias-impl-trait/variance.stderr

@@ -1,10 +1,22 @@
-error[E0657]: `impl Trait` can only capture lifetimes bound at the fn or impl level
+error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from `dyn` type
+  --> $DIR/variance.rs:14:56
+   |
+LL | type NotCapturedLate<'a> = dyn for<'b> Iterator<Item = impl Sized>;
+   |                                                        ^^^^^^^^^^ `impl Trait` implicitly captures all lifetimes in scope
+   |
+note: lifetime declared here
   --> $DIR/variance.rs:14:36
    |
 LL | type NotCapturedLate<'a> = dyn for<'b> Iterator<Item = impl Sized>;
    |                                    ^^
 
-error[E0657]: `impl Trait` can only capture lifetimes bound at the fn or impl level
+error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from `dyn` type
+  --> $DIR/variance.rs:18:49
+   |
+LL | type Captured<'a> = dyn for<'b> Iterator<Item = impl Sized + Captures<'a>>;
+   |                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^ `impl Trait` implicitly captures all lifetimes in scope
+   |
+note: lifetime declared here
   --> $DIR/variance.rs:18:29
    |
 LL | type Captured<'a> = dyn for<'b> Iterator<Item = impl Sized + Captures<'a>>;