Fix tests

example/mini_core.rs

@@ -138,6 +138,14 @@ impl Mul for u8 {
     }
 }
 
+impl Mul for i32 {
+    type Output = Self;
+
+    fn mul(self, rhs: Self) -> Self::Output {
+        self * rhs
+    }
+}
+
 impl Mul for usize {
     type Output = Self;
 
@@ -248,6 +256,14 @@ impl Sub for i16 {
     }
 }
 
+impl Sub for i32 {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
 #[lang = "rem"]
 pub trait Rem<RHS = Self> {
     type Output;