chore(harness): fix clippy error #15701

error[E0658]: attributes on expressions are experimental
  --> harness/macro/src/lib.rs:64:5
   |
64 |     #[cfg(feature = "sp1")]
   |     ^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: see issue #15701 <rust-lang/rust#15701> for more information
   = help: add `#![feature(stmt_expr_attributes)]` to the crate attributes to enable
   = note: this compiler was built on 2024-04-17; consider upgrading it if it is out of date

harness/macro/src/lib.rs

@@ -59,45 +59,47 @@ pub fn entrypoint(input: TokenStream) -> TokenStream {
         };
     }
 
-    #[cfg(feature = "sp1")]
-    let output = quote! {
-        // Set up a global allocator
-        use sp1_zkvm::heap::SimpleAlloc;
-        #[global_allocator]
-        static HEAP: SimpleAlloc = SimpleAlloc;
+    let output = if cfg!(feature = "sp1") {
+        quote! {
+            // Set up a global allocator
+            use sp1_zkvm::heap::SimpleAlloc;
+            #[global_allocator]
+            static HEAP: SimpleAlloc = SimpleAlloc;
 
-        #[cfg(test)]
-        #tests_entry
+            #[cfg(test)]
+            #tests_entry
 
-        #[cfg(not(test))]
-        const ZKVM_ENTRY: fn() = #main_entry;
-        #[cfg(test)]
-        const ZKVM_ENTRY: fn() = run_tests;
+            #[cfg(not(test))]
+            const ZKVM_ENTRY: fn() = #main_entry;
+            #[cfg(test)]
+            const ZKVM_ENTRY: fn() = run_tests;
 
-        mod zkvm_generated_main {
-            #[no_mangle]
-            fn main() {
-                super::ZKVM_ENTRY()
+            mod zkvm_generated_main {
+                #[no_mangle]
+                fn main() {
+                    super::ZKVM_ENTRY()
+                }
             }
         }
-    };
-
-    #[cfg(feature = "risc0")]
-    let output = quote! {
-        #[cfg(test)]
-        #tests_entry
+    } else if cfg!(feature = "risc0") {
+        quote! {
+            #[cfg(test)]
+            #tests_entry
 
-        #[cfg(not(test))]
-        const ZKVM_ENTRY: fn() = #main_entry;
-        #[cfg(test)]
-        const ZKVM_ENTRY: fn() = run_tests;
+            #[cfg(not(test))]
+            const ZKVM_ENTRY: fn() = #main_entry;
+            #[cfg(test)]
+            const ZKVM_ENTRY: fn() = run_tests;
 
-        mod zkvm_generated_main {
-            #[no_mangle]
-            fn main() {
-                super::ZKVM_ENTRY()
+            mod zkvm_generated_main {
+                #[no_mangle]
+                fn main() {
+                    super::ZKVM_ENTRY()
+                }
             }
         }
+    } else {
+        quote! {}
     };
 
     output.into()