Rollup merge of #97188 - carbotaniuman:remove-null-assert, r=RalfJung

Remove unneeded null pointer asserts in ptr2int casts

This removes an assert that a pointer with address 0 has no provenance. This change is needed to support permissive provenance work in Miri, and seems justified by `ptr.with_addr(0)` working and a discussion on Zulip regarding LLVM semantics.

r? `@RalfJung`

Author: GuillaumeGomez

compiler/rustc_const_eval/src/interpret/cast.rs

@@ -225,9 +225,6 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 let addr = u64::try_from(size.truncate(v)).unwrap();
 
                 let ptr = M::ptr_from_addr_cast(&self, addr);
-                if addr == 0 {
-                    assert!(ptr.provenance.is_none(), "null pointer can never have an AllocId");
-                }
                 Scalar::from_maybe_pointer(ptr, self)
             }
 

compiler/rustc_const_eval/src/interpret/memory.rs

@@ -1149,11 +1149,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 Err(ptr) => ptr.into(),
                 Ok(bits) => {
                     let addr = u64::try_from(bits).unwrap();
-                    let ptr = M::ptr_from_addr_transmute(&self, addr);
-                    if addr == 0 {
-                        assert!(ptr.provenance.is_none(), "null pointer can never have an AllocId");
-                    }
-                    ptr
+                    M::ptr_from_addr_transmute(&self, addr)
                 }
             },
         )