chore: upgrade rust-toolchain to nightly-2025-11-20

.github/workflows/lints.yml

@@ -25,7 +25,7 @@ jobs:
           components: rustfmt, clippy
           targets: riscv32im-unknown-none-elf
           # TODO: figure out way to keep this in sync with rust-toolchain.toml automatically
-          toolchain: nightly-2025-08-18
+          toolchain: nightly-2025-11-20
       - name: Cargo cache
         uses: actions/cache@v4
         with:

.github/workflows/tests.yml

@@ -24,7 +24,7 @@ jobs:
         with:
           targets: riscv32im-unknown-none-elf
           # TODO: figure out way to keep this in sync with rust-toolchain.toml automatically
-          toolchain: nightly-2025-08-18
+          toolchain: nightly-2025-11-20
       - name: Cargo cache
         uses: actions/cache@v4
         with:

ceno_cli/src/utils.rs

@@ -78,12 +78,13 @@ pub fn search_workspace_root<P: AsRef<Path>>(path: P) -> anyhow::Result<PathBuf>
 pub fn get_rust_flags() -> String {
     const BASE_RUST_FLAGS: &[&str] = &[
         "-C",
-        "panic=abort",
+        "panic=immediate-abort",
         "-C",
         "link-arg=-Tmemory.x",
         "-C",
         "link-arg=-Tceno_link.x",
         "-Zlocation-detail=none",
+        "-Zunstable-options",
         "-C",
         "passes=lower-atomic",
         "--cfg",
@@ -104,7 +105,7 @@ pub fn apply_cargo_build_std_args(command: &mut Command) {
         "-Z",
         "build-std=alloc,core,compiler_builtins,std,panic_abort,proc_macro",
         "-Z",
-        "build-std-features=compiler-builtins-mem,panic_immediate_abort,default",
+        "build-std-features=compiler-builtins-mem,default",
     ];
     command.args(BASE_CARGO_ARGS);
 }

ceno_rt/riscv32im-ceno-zkvm-elf.json

@@ -28,5 +28,5 @@
   "singlethread": true,
   "target-c-int-width": 32,
   "target-endian": "little",
-  "target-pointer-width": "32"
+  "target-pointer-width": 32
 }

examples/.cargo/config.toml

@@ -9,12 +9,15 @@ build-std = [
 ]
 build-std-features = [
   "compiler-builtins-mem",
-  "panic_immediate_abort",
   "default",
 ]
+panic-immediate-abort = true
 
 [profile.dev]
-panic = "abort"
+panic = "immediate-abort"
+
+[profile.release]
+panic = "immediate-abort"
 
 [build]
 rustflags = [

rust-toolchain.toml

@@ -1,5 +1,5 @@
 [toolchain]
-channel = "nightly-2025-08-18"
+channel = "nightly-2025-11-20"
 targets = ["riscv32im-unknown-none-elf"]
 # We need the sources for build-std.
 components = ["rust-src"]