Fix and slightly improve AstValidator

tests/ui/parser/semantic/impls-nested-within-fns-semantic-0.rs

@@ -0,0 +1,15 @@
+// Regression test for issue #119924.
+// check-pass
+
+pub struct Type;
+
+trait Trait {
+    fn provided() {
+        impl Type {
+            // This visibility qualifier used to get rejected.
+            pub fn perform() {}
+        }
+    }
+}
+
+fn main() {}

tests/ui/parser/semantic/impls-nested-within-fns-semantic-1.rs

@@ -0,0 +1,21 @@
+// Regression test for issue #119924.
+// check-pass
+#![feature(const_trait_impl, effects)]
+
+pub struct Type;
+
+#[const_trait]
+trait Trait {
+    fn required();
+}
+
+impl const Trait for () {
+    fn required() {
+        impl Type {
+            // This visibility qualifier used to get rejected.
+            pub fn perform() {}
+        }
+    }
+}
+
+fn main() {}

tests/ui/parser/semantic/items-nested-within-anon-consts-semantic.rs

@@ -0,0 +1,51 @@
+// Regression test for issues #119924 and #89342.
+// check-pass
+
+struct Type;
+struct Expr<const N: u32>;
+
+trait Trait0 {
+    fn required(_: Expr<{
+        impl Type {
+            // This visibility qualifier used to get rejected.
+            pub fn perform() {}
+        }
+        0
+    }>);
+}
+
+trait Trait1 {}
+
+impl Trait1 for ()
+where
+    [(); {
+        impl Type {
+            // This visibility qualifier used to get rejected.
+            pub const STORE: Self = Self;
+        }
+        0
+    }]:
+{}
+
+trait Trait2<const B: bool> {}
+
+fn f(_: impl Trait2<{
+    // This impl-Trait used to get rejected as "nested" impl-Trait.
+    fn g(_: impl Sized) {}
+    false
+}>) {}
+
+fn scope() {
+    let _: <Parametrized<{
+        // This impl-Trait used get rejected with "not allowed in path parameters".
+        fn run(_: impl Sized) {}
+        0
+    }> as Trait3>::Projected;
+}
+
+trait Trait3 { type Projected; }
+struct Parametrized<const N: usize>;
+
+impl<const N: usize> Trait3 for Parametrized<N> { type Projected = (); }
+
+fn main() {}

tests/ui/rfcs/rfc-2632-const-trait-impl/tilde-const-invalid-places-nested.rs

@@ -0,0 +1,39 @@
+// Regression test for issue #119924.
+#![feature(const_trait_impl, effects)]
+#![allow(incomplete_features)]
+
+pub struct Type;
+
+#[const_trait]
+trait Trait0 {
+    fn provided() {
+        impl Type {
+            fn perform<T: ~const Trait0>() {}
+            //~^ ERROR `~const` is not allowed here
+        }
+    }
+}
+
+struct Expr<const N: u32>;
+
+#[const_trait]
+trait Trait1 {
+    fn required(_: Expr<{
+        impl Type {
+            fn compute<T: ~const Trait1>() {}
+            //~^ ERROR `~const` is not allowed here
+        }
+        0
+    }>);
+}
+
+#[const_trait]
+trait Trait2<const N: u32> {}
+
+const fn operate<T: Trait2<{
+    struct I<U: ~const Trait2<0>>(U);
+    //~^ ERROR `~const` is not allowed here
+    0
+}>>() {}
+
+fn main() {}

tests/ui/rfcs/rfc-2632-const-trait-impl/tilde-const-invalid-places-nested.stderr

@@ -0,0 +1,34 @@
+error: `~const` is not allowed here
+  --> $DIR/tilde-const-invalid-places-nested.rs:11:27
+   |
+LL |             fn perform<T: ~const Trait0>() {}
+   |                           ^^^^^^
+   |
+note: this function is not `const`, so it cannot have `~const` trait bounds
+  --> $DIR/tilde-const-invalid-places-nested.rs:11:16
+   |
+LL |             fn perform<T: ~const Trait0>() {}
+   |                ^^^^^^^
+
+error: `~const` is not allowed here
+  --> $DIR/tilde-const-invalid-places-nested.rs:23:27
+   |
+LL |             fn compute<T: ~const Trait1>() {}
+   |                           ^^^^^^
+   |
+note: this function is not `const`, so it cannot have `~const` trait bounds
+  --> $DIR/tilde-const-invalid-places-nested.rs:23:16
+   |
+LL |             fn compute<T: ~const Trait1>() {}
+   |                ^^^^^^^
+
+error: `~const` is not allowed here
+  --> $DIR/tilde-const-invalid-places-nested.rs:34:17
+   |
+LL |     struct I<U: ~const Trait2<0>>(U);
+   |                 ^^^^^^
+   |
+   = note: this item cannot have `~const` trait bounds
+
+error: aborting due to 3 previous errors
+