Revert "Auto merge of #113166 - moulins:ref-niches-initial, r=oli-obk"

This reverts commit 557359f925, reversing
changes made to 1e6c09a803.

compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs

@@ -979,20 +979,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             return;
         }
 
-        // First, try computing an exact naive layout in case the type is generic.
-        let is_pointer_like = if let Ok(layout) = tcx.naive_layout_of(key) {
-            layout.is_pointer_like(&tcx.data_layout).unwrap_or_else(|| {
-                // Second, we fall back to full layout computation.
-                tcx.layout_of(key)
-                    .ok()
-                    .filter(|l| l.layout.is_pointer_like(&tcx.data_layout))
-                    .is_some()
-            })
-        } else {
-            false
-        };
-
-        if is_pointer_like {
+        if let Ok(layout) = tcx.layout_of(key)
+            && layout.layout.is_pointer_like(&tcx.data_layout)
+        {
             candidates.vec.push(BuiltinCandidate { has_nested: false });
         }
     }