Auto merge of #124219 - gurry:122989-ice-unexpected-anon-const, r=compiler-errors

Do not ICE on `AnonConst`s in `diagnostic_hir_wf_check`

Fixes #122989

Below is the snippet from #122989 that ICEs:
```rust
trait Traitor<const N: N<2> = 1, const N: N<2> = N> {
    fn N(&N) -> N<2> {
        M
    }
}

trait N<const N: Traitor<2> = 12> {}
```

The `AnonConst` that triggers the ICE is the `2` in the param `const N: N<2> = 1`. The currently existing code in `diagnostic_hir_wf_check` deals only with `AnonConst`s that are default values of some param, but  the `2` is not a default value. It is just an `AnonConst` HIR node inside a `TraitRef` HIR node corresponding to `N<2>`. Therefore the existing code cannot handle it and this PR ensures that it does.

1 files changed, 8 insertions, 6 deletions

diff --git a/compiler/rustc_hir_analysis/src/hir_wf_check.rs b/compiler/rustc_hir_analysis/src/hir_wf_check.rs
index 7014b23ff07..d6ba5fa9b5b 100644
--- a/compiler/rustc_hir_analysis/src/hir_wf_check.rs
+++ b/compiler/rustc_hir_analysis/src/hir_wf_check.rs
@@ -163,15 +163,17 @@ fn diagnostic_hir_wf_check<'tcx>(
                 kind: hir::GenericParamKind::Type { default: Some(ty), .. },
                 ..
             }) => vec![*ty],
-            hir::Node::AnonConst(_)
-                if let Some(const_param_id) =
-                    tcx.hir().opt_const_param_default_param_def_id(hir_id)
+            hir::Node::AnonConst(_) => {
+                if let Some(const_param_id) = tcx.hir().opt_const_param_default_param_def_id(hir_id)
                     && let hir::Node::GenericParam(hir::GenericParam {
                         kind: hir::GenericParamKind::Const { ty, .. },
                         ..
-                    }) = tcx.hir_node_by_def_id(const_param_id) =>
-            {
-                vec![*ty]
+                    }) = tcx.hir_node_by_def_id(const_param_id)
+                {
+                    vec![*ty]
+                } else {
+                    vec![]
+                }
             }
             ref node => bug!("Unexpected node {:?}", node),
         },