Upgrade the toolchain to 2025-02-21 (#3899)

Upstream PRs requiring changes:

rust-lang/rust#135994
rust-lang/rust#136466

By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 and MIT licenses.

kani-compiler/src/codegen_cprover_gotoc/codegen/rvalue.rs

@@ -667,7 +667,7 @@ impl GotocCtx<'_> {
                 assert!(operands.len() == 2);
                 let typ = self.codegen_ty_stable(res_ty);
                 let layout = self.layout_of_stable(res_ty);
-                assert!(layout.ty.is_unsafe_ptr());
+                assert!(layout.ty.is_raw_ptr());
                 let data = self.codegen_operand_stable(&operands[0]);
                 match pointee_ty.kind() {
                     TyKind::RigidTy(RigidTy::Slice(inner_ty)) => {

kani-compiler/src/kani_middle/mod.rs

@@ -37,7 +37,7 @@ pub mod transform;
 /// error was found.
 pub fn check_crate_items(tcx: TyCtxt, ignore_asm: bool) {
     let krate = tcx.crate_name(LOCAL_CRATE);
-    for item in tcx.hir().items() {
+    for item in tcx.hir_free_items() {
         let def_id = item.owner_id.def_id.to_def_id();
         KaniAttributes::for_item(tcx, def_id).check_attributes();
         if tcx.def_kind(def_id) == DefKind::GlobalAsm {

kani-compiler/src/kani_middle/resolve.rs

@@ -430,8 +430,8 @@ fn resolve_relative(tcx: TyCtxt, current_module: LocalModDefId, name: &str) -> R
     debug!(?name, ?current_module, "resolve_relative");
 
     let mut glob_imports = vec![];
-    let result = tcx.hir().module_items(current_module).find_map(|item_id| {
-        let item = tcx.hir().item(item_id);
+    let result = tcx.hir_module_free_items(current_module).find_map(|item_id| {
+        let item = tcx.hir_item(item_id);
         if item.ident.as_str() == name {
             match item.kind {
                 ItemKind::Use(use_path, UseKind::Single) => use_path.res[0].opt_def_id(),

rust-toolchain.toml

@@ -2,5 +2,5 @@
 # SPDX-License-Identifier: Apache-2.0 OR MIT
 
 [toolchain]
-channel = "nightly-2025-02-12"
+channel = "nightly-2025-02-21"
 components = ["llvm-tools", "rustc-dev", "rust-src", "rustfmt"]