Rollup merge of rust-lang#157400 - kohsine:late-bound-assoc-type-reg-test, r=Kivooeo

Add regression test for late-bound type param in nested `impl Trait`

Regression test for rust-lang#132055

Author: JonathanBrouwer

tests/ui/traits/non_lifetime_binders/late-bound-assoc-type.rs

@@ -0,0 +1,19 @@
+#![feature(non_lifetime_binders)]
+
+//! Regression test for https://github.com/rust-lang/rust/issues/132055.
+//! Compiler gave ICE with late-bound type parameter in nested `impl Trait` on
+//! associated type.
+
+trait Trait<T: ?Sized> {
+    type Assoc<'a> = i32;
+    //~^ ERROR associated type defaults are unstable
+}
+
+fn produce() -> impl for<T> Trait<(), Assoc = impl Trait<T>> {
+    //~^ ERROR cannot capture late-bound type parameter in nested `impl Trait`
+    //~| ERROR missing generics for associated type `Trait::Assoc`
+    //~| ERROR missing generics for associated type `Trait::Assoc`
+    //~| ERROR the trait bound `{integer}: Trait<()>` is not satisfied
+    16
+}
+//~^ ERROR `main` function not found in crate `late_bound_assoc_type`

tests/ui/traits/non_lifetime_binders/late-bound-assoc-type.stderr

@@ -0,0 +1,74 @@
+error[E0658]: associated type defaults are unstable
+  --> $DIR/late-bound-assoc-type.rs:8:5
+   |
+LL |     type Assoc<'a> = i32;
+   |     ^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #29661 <https://github.com/rust-lang/rust/issues/29661> for more information
+   = help: add `#![feature(associated_type_defaults)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error[E0601]: `main` function not found in crate `late_bound_assoc_type`
+  --> $DIR/late-bound-assoc-type.rs:18:2
+   |
+LL | }
+   |  ^ consider adding a `main` function to `$DIR/late-bound-assoc-type.rs`
+
+error: cannot capture late-bound type parameter in nested `impl Trait`
+  --> $DIR/late-bound-assoc-type.rs:12:58
+   |
+LL | fn produce() -> impl for<T> Trait<(), Assoc = impl Trait<T>> {
+   |                          - parameter defined here        ^
+
+error[E0107]: missing generics for associated type `Trait::Assoc`
+  --> $DIR/late-bound-assoc-type.rs:12:39
+   |
+LL | fn produce() -> impl for<T> Trait<(), Assoc = impl Trait<T>> {
+   |                                       ^^^^^ expected 1 lifetime argument
+   |
+note: associated type defined here, with 1 lifetime parameter: `'a`
+  --> $DIR/late-bound-assoc-type.rs:8:10
+   |
+LL |     type Assoc<'a> = i32;
+   |          ^^^^^ --
+help: add missing lifetime argument
+   |
+LL | fn produce() -> impl for<T> Trait<(), Assoc<'a> = impl Trait<T>> {
+   |                                            ++++
+
+error[E0107]: missing generics for associated type `Trait::Assoc`
+  --> $DIR/late-bound-assoc-type.rs:12:39
+   |
+LL | fn produce() -> impl for<T> Trait<(), Assoc = impl Trait<T>> {
+   |                                       ^^^^^ expected 1 lifetime argument
+   |
+note: associated type defined here, with 1 lifetime parameter: `'a`
+  --> $DIR/late-bound-assoc-type.rs:8:10
+   |
+LL |     type Assoc<'a> = i32;
+   |          ^^^^^ --
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+help: add missing lifetime argument
+   |
+LL | fn produce() -> impl for<T> Trait<(), Assoc<'a> = impl Trait<T>> {
+   |                                            ++++
+
+error[E0277]: the trait bound `{integer}: Trait<()>` is not satisfied
+  --> $DIR/late-bound-assoc-type.rs:12:17
+   |
+LL | fn produce() -> impl for<T> Trait<(), Assoc = impl Trait<T>> {
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Trait<()>` is not implemented for `{integer}`
+...
+LL |     16
+   |     -- return type was inferred to be `{integer}` here
+   |
+help: this trait has no implementations, consider adding one
+  --> $DIR/late-bound-assoc-type.rs:7:1
+   |
+LL | trait Trait<T: ?Sized> {
+   | ^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 6 previous errors
+
+Some errors have detailed explanations: E0107, E0277, E0601, E0658.
+For more information about an error, try `rustc --explain E0107`.