Forbid nested opaque types to reference HRTB from opaque types.

11 files changed, 89 insertions, 94 deletions

diff --git a/compiler/rustc_resolve/src/late/lifetimes.rs b/compiler/rustc_resolve/src/late/lifetimes.rs
index afb19d7df9f..35caeefe157 100644
--- a/compiler/rustc_resolve/src/late/lifetimes.rs
+++ b/compiler/rustc_resolve/src/late/lifetimes.rs
@@ -1036,6 +1036,20 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
                         }
                         self.uninsert_lifetime_on_error(lifetime, def.unwrap());
                     }
+                    if let hir::Node::Item(hir::Item {
+                        kind: hir::ItemKind::OpaqueTy { .. }, ..
+                    }) = self.tcx.hir().get(parent_id)
+                    {
+                        if !self.trait_definition_only {
+                            let mut err = self.tcx.sess.struct_span_err(
+                                lifetime.span,
+                                "higher kinded lifetime bounds on nested opaque types are not supported yet",
+                            );
+                            err.span_note(self.tcx.def_span(def_id), "lifetime declared here");
+                            err.emit();
+                        }
+                        self.uninsert_lifetime_on_error(lifetime, def.unwrap());
+                    }
                 }
 
                 // We want to start our early-bound indices at the end of the parent scope,
diff --git a/src/test/ui/impl-trait/issues/issue-54895.rs b/src/test/ui/impl-trait/issues/issue-54895.rs
index a70166e03a7..8d7a1d56f83 100644
--- a/src/test/ui/impl-trait/issues/issue-54895.rs
+++ b/src/test/ui/impl-trait/issues/issue-54895.rs
@@ -1,5 +1,3 @@
-// check-pass
-
 trait Trait<'a> {
     type Out;
     fn call(&'a self) -> Self::Out;
@@ -15,6 +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
     X(())
 }
 
diff --git a/src/test/ui/impl-trait/issues/issue-54895.stderr b/src/test/ui/impl-trait/issues/issue-54895.stderr
new file mode 100644
index 00000000000..7d22f027a6d
--- /dev/null
+++ b/src/test/ui/impl-trait/issues/issue-54895.stderr
@@ -0,0 +1,14 @@
+error: higher kinded lifetime bounds on nested opaque types are not supported yet
+  --> $DIR/issue-54895.rs:15:53
+   |
+LL | fn f() -> impl for<'a> Trait<'a, Out = impl Sized + 'a> {
+   |                                                     ^^
+   |
+note: lifetime declared here
+  --> $DIR/issue-54895.rs:15:20
+   |
+LL | fn f() -> impl for<'a> Trait<'a, Out = impl Sized + 'a> {
+   |                    ^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/impl-trait/issues/issue-67830.nll.stderr b/src/test/ui/impl-trait/issues/issue-67830.nll.stderr
deleted file mode 100644
index 17fbe046e3a..00000000000
--- a/src/test/ui/impl-trait/issues/issue-67830.nll.stderr
+++ /dev/null
@@ -1,20 +0,0 @@
-error: implementation of `FnOnce` is not general enough
-  --> $DIR/issue-67830.rs:23:5
-   |
-LL |     Wrap(|a| Some(a).into_iter())
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ implementation of `FnOnce` is not general enough
-   |
-   = note: closure with signature `fn(&'2 A) -> std::option::IntoIter<&A>` must implement `FnOnce<(&'1 A,)>`, for any lifetime `'1`...
-   = note: ...but it actually implements `FnOnce<(&'2 A,)>`, for some specific lifetime `'2`
-
-error: implementation of `FnOnce` is not general enough
-  --> $DIR/issue-67830.rs:23:5
-   |
-LL |     Wrap(|a| Some(a).into_iter())
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ implementation of `FnOnce` is not general enough
-   |
-   = note: closure with signature `fn(&'2 A) -> std::option::IntoIter<&A>` must implement `FnOnce<(&'1 A,)>`, for any lifetime `'1`...
-   = note: ...but it actually implements `FnOnce<(&'2 A,)>`, for some specific lifetime `'2`
-
-error: aborting due to 2 previous errors
-
diff --git a/src/test/ui/impl-trait/issues/issue-67830.rs b/src/test/ui/impl-trait/issues/issue-67830.rs
index a308d975b43..92f7e005dbf 100644
--- a/src/test/ui/impl-trait/issues/issue-67830.rs
+++ b/src/test/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 implementation of `FnOnce` is not general enough
+    //~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
     Wrap(|a| Some(a).into_iter())
 }
 
diff --git a/src/test/ui/impl-trait/issues/issue-67830.stderr b/src/test/ui/impl-trait/issues/issue-67830.stderr
index 4c0490c721b..d3ea8cb0377 100644
--- a/src/test/ui/impl-trait/issues/issue-67830.stderr
+++ b/src/test/ui/impl-trait/issues/issue-67830.stderr
@@ -1,11 +1,14 @@
-error: implementation of `FnOnce` is not general enough
-  --> $DIR/issue-67830.rs:21:14
+error: higher kinded lifetime bounds on nested opaque types are not supported yet
+  --> $DIR/issue-67830.rs:21:62
    |
 LL | fn test() -> impl for<'a> MyFn<&'a A, Output=impl Iterator + 'a> {
-   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ implementation of `FnOnce` is not general enough
+   |                                                              ^^
    |
-   = note: closure with signature `fn(&'2 A) -> std::option::IntoIter<&A>` must implement `FnOnce<(&'1 A,)>`, for any lifetime `'1`...
-   = note: ...but it actually implements `FnOnce<(&'2 A,)>`, for some specific lifetime `'2`
+note: lifetime declared here
+  --> $DIR/issue-67830.rs:21:23
+   |
+LL | fn test() -> impl for<'a> MyFn<&'a A, Output=impl Iterator + 'a> {
+   |                       ^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/impl-trait/issues/issue-88236-2.nll.stderr b/src/test/ui/impl-trait/issues/issue-88236-2.nll.stderr
deleted file mode 100644
index 9cf8ff76c87..00000000000
--- a/src/test/ui/impl-trait/issues/issue-88236-2.nll.stderr
+++ /dev/null
@@ -1,51 +0,0 @@
-error: implementation of `Hrtb` is not general enough
-  --> $DIR/issue-88236-2.rs:17:5
-   |
-LL |     &()
-   |     ^^^ implementation of `Hrtb` is not general enough
-   |
-   = note: `Hrtb<'0>` would have to be implemented for the type `&()`, for any lifetime `'0`...
-   = note: ...but `Hrtb<'1>` is actually implemented for the type `&'1 ()`, for some specific lifetime `'1`
-
-error: implementation of `Hrtb` is not general enough
-  --> $DIR/issue-88236-2.rs:17:5
-   |
-LL |     &()
-   |     ^^^ implementation of `Hrtb` is not general enough
-   |
-   = note: `Hrtb<'0>` would have to be implemented for the type `&()`, for any lifetime `'0`...
-   = note: ...but `Hrtb<'1>` is actually implemented for the type `&'1 ()`, for some specific lifetime `'1`
-
-error: lifetime may not live long enough
-  --> $DIR/issue-88236-2.rs:20:5
-   |
-LL | fn make_bad_impl<'b>(x: &'b ()) -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {
-   |                  -- lifetime `'b` defined here
-LL |     x
-   |     ^ returning this value requires that `'b` must outlive `'static`
-   |
-help: to allow this `impl Trait` to capture borrowed data with lifetime `'b`, add `'b` as a bound
-   |
-LL | fn make_bad_impl<'b>(x: &'b ()) -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> + 'b {
-   |                                                                                  ++++
-
-error: implementation of `Hrtb` is not general enough
-  --> $DIR/issue-88236-2.rs:20:5
-   |
-LL |     x
-   |     ^ implementation of `Hrtb` is not general enough
-   |
-   = note: `Hrtb<'0>` would have to be implemented for the type `&()`, for any lifetime `'0`...
-   = note: ...but `Hrtb<'1>` is actually implemented for the type `&'1 ()`, for some specific lifetime `'1`
-
-error: implementation of `Hrtb` is not general enough
-  --> $DIR/issue-88236-2.rs:20:5
-   |
-LL |     x
-   |     ^ implementation of `Hrtb` is not general enough
-   |
-   = note: `Hrtb<'0>` would have to be implemented for the type `&()`, for any lifetime `'0`...
-   = note: ...but `Hrtb<'1>` is actually implemented for the type `&'1 ()`, for some specific lifetime `'1`
-
-error: aborting due to 5 previous errors
-
diff --git a/src/test/ui/impl-trait/issues/issue-88236-2.rs b/src/test/ui/impl-trait/issues/issue-88236-2.rs
index af26a1f54c4..fde8a6704cc 100644
--- a/src/test/ui/impl-trait/issues/issue-88236-2.rs
+++ b/src/test/ui/impl-trait/issues/issue-88236-2.rs
@@ -13,11 +13,16 @@ 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
+
 fn make_weird_impl<'b>(x: &'b ()) -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {
-    &() //~^ ERROR implementation of `Hrtb` is not general enough
+    //~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
+    &()
 }
+
 fn make_bad_impl<'b>(x: &'b ()) -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {
-    x //~^ ERROR implementation of `Hrtb` is not general enough
+    //~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
+    x
 }
 
 fn main() {}
diff --git a/src/test/ui/impl-trait/issues/issue-88236-2.stderr b/src/test/ui/impl-trait/issues/issue-88236-2.stderr
index 9574b880f7d..8605d07abe9 100644
--- a/src/test/ui/impl-trait/issues/issue-88236-2.stderr
+++ b/src/test/ui/impl-trait/issues/issue-88236-2.stderr
@@ -1,20 +1,38 @@
-error: implementation of `Hrtb` is not general enough
-  --> $DIR/issue-88236-2.rs:16:38
+error: higher kinded lifetime bounds on nested opaque types are not supported yet
+  --> $DIR/issue-88236-2.rs:15:61
+   |
+LL | fn make_impl() -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {}
+   |                                                             ^^
+   |
+note: lifetime declared here
+  --> $DIR/issue-88236-2.rs:15:28
+   |
+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
+  --> $DIR/issue-88236-2.rs:18:80
    |
 LL | fn make_weird_impl<'b>(x: &'b ()) -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {
-   |                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ implementation of `Hrtb` is not general enough
+   |                                                                                ^^
    |
-   = note: `Hrtb<'0>` would have to be implemented for the type `&()`, for any lifetime `'0`...
-   = note: ...but `Hrtb<'1>` is actually implemented for the type `&'1 ()`, for some specific lifetime `'1`
+note: lifetime declared here
+  --> $DIR/issue-88236-2.rs:18:47
+   |
+LL | fn make_weird_impl<'b>(x: &'b ()) -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {
+   |                                               ^^
 
-error: implementation of `Hrtb` is not general enough
-  --> $DIR/issue-88236-2.rs:19:36
+error: higher kinded lifetime bounds on nested opaque types are not supported yet
+  --> $DIR/issue-88236-2.rs:23:78
    |
 LL | fn make_bad_impl<'b>(x: &'b ()) -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {
-   |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ implementation of `Hrtb` is not general enough
+   |                                                                              ^^
    |
-   = note: `Hrtb<'1>` would have to be implemented for the type `&()`, for any lifetime `'1`...
-   = note: ...but `Hrtb<'_>` is actually implemented for the type `&()`
+note: lifetime declared here
+  --> $DIR/issue-88236-2.rs:23:45
+   |
+LL | fn make_bad_impl<'b>(x: &'b ()) -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {
+   |                                             ^^
 
-error: aborting due to 2 previous errors
+error: aborting due to 3 previous errors
 
diff --git a/src/test/ui/impl-trait/issues/issue-88236.rs b/src/test/ui/impl-trait/issues/issue-88236.rs
index 2ea35270a7e..36d12417354 100644
--- a/src/test/ui/impl-trait/issues/issue-88236.rs
+++ b/src/test/ui/impl-trait/issues/issue-88236.rs
@@ -1,5 +1,3 @@
-// check-pass
-
 // this used to cause stack overflows
 
 trait Hrtb<'a> {
@@ -15,5 +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
 
 fn main() {}
diff --git a/src/test/ui/impl-trait/issues/issue-88236.stderr b/src/test/ui/impl-trait/issues/issue-88236.stderr
new file mode 100644
index 00000000000..7a4cc57b088
--- /dev/null
+++ b/src/test/ui/impl-trait/issues/issue-88236.stderr
@@ -0,0 +1,14 @@
+error: higher kinded lifetime bounds on nested opaque types are not supported yet
+  --> $DIR/issue-88236.rs:15:61
+   |
+LL | fn make_impl() -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {}
+   |                                                             ^^
+   |
+note: lifetime declared here
+  --> $DIR/issue-88236.rs:15:28
+   |
+LL | fn make_impl() -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {}
+   |                            ^^
+
+error: aborting due to previous error
+