Use the correct return type for puts

example/alloc_example.rs

@@ -13,7 +13,7 @@
 
 #[link(name = "c")]
 extern "C" {
-    fn puts(s: *const u8);
+    fn puts(s: *const u8) -> i32;
 }
 
 #[panic_handler]

example/mini_core.rs

@@ -488,7 +488,7 @@ pub mod intrinsics {
 pub mod libc {
     #[link(name = "c")]
     extern "C" {
-        pub fn puts(s: *const u8);
+        pub fn puts(s: *const u8) -> i32;
         pub fn printf(format: *const i8, ...) -> i32;
         pub fn malloc(size: usize) -> *mut u8;
         pub fn free(ptr: *mut u8);

src/trap.rs

@@ -12,7 +12,7 @@ fn codegen_print(fx: &mut FunctionCx<'_, '_, impl cranelift_module::Backend>, ms
             &Signature {
                 call_conv: CallConv::triple_default(fx.triple()),
                 params: vec![AbiParam::new(pointer_ty(fx.tcx))],
-                returns: vec![],
+                returns: vec![AbiParam::new(types::I32)],
             },
         )
         .unwrap();