Remove some now-dead code

Author: oli-obk

compiler/rustc_const_eval/src/interpret/intern.rs

@@ -14,7 +14,7 @@
 //! about type information, we want to avoid doing that.
 
 use rustc_ast::Mutability;
-use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
+use rustc_data_structures::fx::FxIndexMap;
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir as hir;
 use rustc_middle::mir::interpret::{CtfeProvenance, InterpResult};
@@ -127,9 +127,6 @@ pub fn intern_const_alloc_recursive<
     let base_alloc_id = ret.ptr().provenance.unwrap().alloc_id();
     let mut todo: Vec<_> =
         intern_shallow(ecx, base_alloc_id, base_mutability).unwrap().map(|prov| prov).collect();
-    // We need to distinguish "has just been interned" from "was already in `tcx`",
-    // so we track this in a separate set.
-    let mut just_interned = FxHashSet::default();
     // Whether we encountered a bad mutable pointer.
     // We want to first report "dangling" and then "mutable", so we need to delay reporting these
     // errors.
@@ -150,22 +147,10 @@ pub fn intern_const_alloc_recursive<
             debug_assert!(!ecx.memory.alloc_map.contains_key(&alloc_id));
             continue;
         }
-        just_interned.insert(alloc_id);
         if intern_kind != InternKind::Promoted
             && inner_mutability == Mutability::Not
             && !prov.immutable()
         {
-            if ecx.tcx.try_get_global_alloc(alloc_id).is_some()
-                && !just_interned.contains(&alloc_id)
-            {
-                // This is a pointer to some memory from another constant. We encounter mutable
-                // pointers to such memory since we do not always track immutability through
-                // these "global" pointers. Allowing them is harmless; the point of these checks
-                // during interning is to justify why we intern the *new* allocations immutably,
-                // so we can completely ignore existing allocations. We also don't need to add
-                // this to the todo list, since after all it is already interned.
-                continue;
-            }
             // Found a mutable pointer inside a const where inner allocations should be
             // immutable. We exclude promoteds from this, since things like `&mut []` and
             // `&None::<Cell<i32>>` lead to promotion that can produce mutable pointers. We rely