[DO NOT MERGE] Use stable 1.85.1 release

.cargo/config.toml

@@ -20,6 +20,7 @@ KANI_SYSROOT ={value = "target/kani", relative = true}
 KANI_BUILD_LIBS ={value = "target/build-libs", relative = true}
 # Build Kani library without `build-std`.
 KANI_LEGACY_LIBS ={value = "target/legacy-libs", relative = true}
+RUSTC_BOOTSTRAP = "1"
 
 [target.'cfg(all())']
 rustflags = [ # Global lints/warnings. Need to use underscore instead of -.

kani-driver/src/call_cargo.rs

@@ -207,6 +207,7 @@ crate-type = ["lib"]
                     // Use CARGO_ENCODED_RUSTFLAGS instead of RUSTFLAGS is preferred. See
                     // https://doc.rust-lang.org/cargo/reference/environment-variables.html
                     .env("CARGO_ENCODED_RUSTFLAGS", rustc_args.join(OsStr::new("\x1f")))
+                    .env("RUSTC_BOOTSTRAP", "1")
                     .env("CARGO_TERM_PROGRESS_WHEN", "never");
 
                 match self.run_build_target(cmd, verification_target.target()) {

kani-driver/src/call_single_file.rs

@@ -84,6 +84,7 @@ impl KaniSession {
         let mut cmd = Command::new(&self.kani_compiler);
         let kani_compiler_args = to_rustc_arg(kani_args);
         cmd.arg(kani_compiler_args).args(rustc_args);
+        cmd.env("RUSTC_BOOTSTRAP", "1");
 
         if self.args.common_args.quiet {
             self.run_suppress(cmd)?;

rust-toolchain.toml

@@ -2,5 +2,5 @@
 # SPDX-License-Identifier: Apache-2.0 OR MIT
 
 [toolchain]
-channel = "nightly-2025-01-24"
+channel = "1.85.1"
 components = ["llvm-tools", "rustc-dev", "rust-src", "rustfmt"]