Fix clippy error by providing fallback main function for benchmark in debug mode

Co-authored-by: jsturtevant <648372+jsturtevant@users.noreply.github.com>

Author: Copilot

src/hyperlight_host/benches/benchmarks.rs

@@ -17,26 +17,34 @@ limitations under the License.
 // Benchmarks are only meaningful and should only run with optimized builds.
 // Unoptimized builds have different performance characteristics and would not provide
 // useful benchmarking data for performance regression testing.
-#![cfg(optimized_build)]
 
+#[cfg(optimized_build)]
 use criterion::{Criterion, criterion_group, criterion_main};
+#[cfg(optimized_build)]
 use hyperlight_host::GuestBinary;
+#[cfg(optimized_build)]
 use hyperlight_host::sandbox::{
     Callable, MultiUseSandbox, SandboxConfiguration, UninitializedSandbox,
 };
+#[cfg(optimized_build)]
 use hyperlight_host::sandbox_state::sandbox::EvolvableSandbox;
+#[cfg(optimized_build)]
 use hyperlight_host::sandbox_state::transition::Noop;
+#[cfg(optimized_build)]
 use hyperlight_testing::simple_guest_as_string;
 
+#[cfg(optimized_build)]
 fn create_uninit_sandbox() -> UninitializedSandbox {
     let path = simple_guest_as_string().unwrap();
     UninitializedSandbox::new(GuestBinary::FilePath(path), None).unwrap()
 }
 
+#[cfg(optimized_build)]
 fn create_multiuse_sandbox() -> MultiUseSandbox {
     create_uninit_sandbox().evolve(Noop::default()).unwrap()
 }
 
+#[cfg(optimized_build)]
 fn guest_call_benchmark(c: &mut Criterion) {
     let mut group = c.benchmark_group("guest_functions");
 
@@ -84,6 +92,7 @@ fn guest_call_benchmark(c: &mut Criterion) {
     group.finish();
 }
 
+#[cfg(optimized_build)]
 fn guest_call_benchmark_large_param(c: &mut Criterion) {
     let mut group = c.benchmark_group("guest_functions_with_large_parameters");
     #[cfg(target_os = "windows")]
@@ -119,6 +128,7 @@ fn guest_call_benchmark_large_param(c: &mut Criterion) {
     group.finish();
 }
 
+#[cfg(optimized_build)]
 fn sandbox_benchmark(c: &mut Criterion) {
     let mut group = c.benchmark_group("sandboxes");
 
@@ -158,10 +168,21 @@ fn sandbox_benchmark(c: &mut Criterion) {
     group.finish();
 }
 
+#[cfg(optimized_build)]
 criterion_group! {
     name = benches;
     config = Criterion::default();
     targets = guest_call_benchmark, sandbox_benchmark, guest_call_benchmark_large_param
 }
 
+#[cfg(optimized_build)]
 criterion_main!(benches);
+
+// Provide a fallback main function for unoptimized builds
+// This prevents compilation errors while providing a clear message
+#[cfg(unoptimized_build)]
+fn main() {
+    panic!(
+        "Benchmarks must be run with optimized builds only. Use `cargo bench --release` or `just bench`."
+    );
+}