fix: Error on illegal [const]s inside blocks within legal positions

Author: ShoyuVanilla

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -1623,6 +1623,12 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
             _ => self.with_in_trait_impl(None, |this| visit::walk_assoc_item(this, item, ctxt)),
         }
     }
+
+    fn visit_block(&mut self, block: &'a Block) {
+        // Conditional consts should not be used in invalid contexts—such as const bodies—even if
+        // they appear within the generic parameters of const traits or impls.
+        self.with_tilde_const(Some(TildeConstReason::Item), |this| visit::walk_block(this, block))
+    }
 }
 
 /// When encountering an equality constraint in a `where` clause, emit an error. If the code seems

tests/ui/traits/const-traits/conditionally-const-in-struct-args.rs

@@ -1,7 +1,3 @@
-//@ compile-flags: -Znext-solver
-//@ known-bug: #132067
-//@ check-pass
-
 #![feature(const_trait_impl)]
 
 struct S;
@@ -11,7 +7,11 @@ trait Trait<const N: u32> {}
 const fn f<
     T: Trait<
         {
+            const fn g<U: [const] Trait<0>>() {}
+
             struct I<U: [const] Trait<0>>(U);
+            //~^ ERROR `[const]` is not allowed here
+
             0
         },
     >,

tests/ui/traits/const-traits/conditionally-const-in-struct-args.stderr

@@ -0,0 +1,10 @@
+error: `[const]` is not allowed here
+  --> $DIR/conditionally-const-in-struct-args.rs:12:25
+   |
+LL |             struct I<U: [const] Trait<0>>(U);
+   |                         ^^^^^^^
+   |
+   = note: this item cannot have `[const]` trait bounds
+
+error: aborting due to 1 previous error
+

tests/ui/unpretty/exhaustive.expanded.stdout

@@ -602,7 +602,6 @@ mod types {
         let _: impl Send + 'static;
         let _: impl 'static + Send;
         let _: impl ?Sized;
-        let _: impl [const] Clone;
         let _: impl for<'a> Send;
     }
     /// TyKind::Paren

tests/ui/unpretty/exhaustive.hir.stderr

@@ -147,17 +147,6 @@ LL |         let _: impl ?Sized;
 error[E0562]: `impl Trait` is not allowed in the type of variable bindings
   --> $DIR/exhaustive.rs:810:16
    |
-LL |         let _: impl [const] Clone;
-   |                ^^^^^^^^^^^^^^^^^^
-   |
-   = note: `impl Trait` is only allowed in arguments and return types of functions and methods
-   = note: see issue #63065 <https://github.com/rust-lang/rust/issues/63065> for more information
-   = help: add `#![feature(impl_trait_in_bindings)]` 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[E0562]: `impl Trait` is not allowed in the type of variable bindings
-  --> $DIR/exhaustive.rs:811:16
-   |
 LL |         let _: impl for<'a> Send;
    |                ^^^^^^^^^^^^^^^^^
    |
@@ -166,7 +155,7 @@ LL |         let _: impl for<'a> Send;
    = help: add `#![feature(impl_trait_in_bindings)]` 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: aborting due to 20 previous errors
+error: aborting due to 19 previous errors
 
 Some errors have detailed explanations: E0214, E0562, E0697, E0703, E0728.
 For more information about an error, try `rustc --explain E0214`.

tests/ui/unpretty/exhaustive.hir.stdout

@@ -668,7 +668,6 @@ mod types {
         let _: (/*ERROR*/);
         let _: (/*ERROR*/);
         let _: (/*ERROR*/);
-        let _: (/*ERROR*/);
     }
     /// TyKind::Paren
     fn ty_paren() { let _: T; }

tests/ui/unpretty/exhaustive.rs

@@ -807,7 +807,6 @@ mod types {
         let _: impl Send + 'static;     //[hir]~ ERROR `impl Trait` is not allowed
         let _: impl 'static + Send;     //[hir]~ ERROR `impl Trait` is not allowed
         let _: impl ?Sized;             //[hir]~ ERROR `impl Trait` is not allowed
-        let _: impl [const] Clone;       //[hir]~ ERROR `impl Trait` is not allowed
         let _: impl for<'a> Send;       //[hir]~ ERROR `impl Trait` is not allowed
     }