Only keep predicates on Self when checking dyn TraitAlias.

Author: cjgillot

compiler/rustc_typeck/src/astconv/mod.rs

@@ -1334,8 +1334,9 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         // is used and no 'maybe' bounds are used.
         let expanded_traits =
             traits::expand_trait_aliases(tcx, bounds.trait_bounds.iter().map(|&(a, b, _)| (a, b)));
-        let (mut auto_traits, regular_traits): (Vec<_>, Vec<_>) =
-            expanded_traits.partition(|i| tcx.trait_is_auto(i.trait_ref().def_id()));
+        let (mut auto_traits, regular_traits): (Vec<_>, Vec<_>) = expanded_traits
+            .filter(|i| i.trait_ref().self_ty().skip_binder() == dummy_self)
+            .partition(|i| tcx.trait_is_auto(i.trait_ref().def_id()));
         if regular_traits.len() > 1 {
             let first_trait = &regular_traits[0];
             let additional_trait = &regular_traits[1];

src/test/ui/traits/issue-65673.rs

@@ -7,6 +7,6 @@ trait Alias<T> = where T: Trait;
 
 impl<T> WithType for T {
     type Ctx = dyn Alias<T>;
-//~^ ERROR the size for values of type `(dyn Trait + 'static)` cannot be known at compilation time
+    //~^ ERROR at least one trait is required for an object type [E0224]
 }
 fn main() {}

src/test/ui/traits/issue-65673.stderr

@@ -1,16 +1,9 @@
-error[E0277]: the size for values of type `(dyn Trait + 'static)` cannot be known at compilation time
+error[E0224]: at least one trait is required for an object type
   --> $DIR/issue-65673.rs:9:16
    |
 LL |     type Ctx = dyn Alias<T>;
-   |                ^^^^^^^^^^^^ doesn't have a size known at compile-time
-   |
-   = help: the trait `Sized` is not implemented for `(dyn Trait + 'static)`
-note: required by a bound in `WithType::Ctx`
-  --> $DIR/issue-65673.rs:4:5
-   |
-LL |     type Ctx;
-   |     ^^^^^^^^^ required by this bound in `WithType::Ctx`
+   |                ^^^^^^^^^^^^
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0277`.
+For more information about this error, try `rustc --explain E0224`.

src/test/ui/traits/issue-96664.rs

@@ -0,0 +1,16 @@
+// check-pass
+
+#![feature(trait_alias)]
+
+pub trait State = Clone + Send + Sync + PartialOrd + PartialEq + std::fmt::Display;
+pub trait RandState<S: State> = FnMut() -> S + Send;
+
+pub trait Evaluator {
+    type State;
+}
+
+pub struct Evolver<E: Evaluator> {
+    rand_state: Box<dyn RandState<E::State>>,
+}
+
+fn main() {}