Rust: Add test with method on borrow

Author: paldepind

rust/ql/test/library-tests/type-inference/main.rs

@@ -1079,6 +1079,11 @@ mod method_call_type_conversion {
     #[derive(Debug, Copy, Clone)]
     struct S2;
 
+    #[derive(Debug, Copy, Clone, Default)]
+    struct MyInt {
+        a: i64,
+    }
+
     impl<T> S<T> {
         fn m1(self) -> T {
             self.0 // $ fieldof=S
@@ -1093,6 +1098,24 @@ mod method_call_type_conversion {
         }
     }
 
+    trait ATrait {
+        fn method_on_borrow(&self) -> i64;
+        fn method_not_on_borrow(self) -> i64;
+    }
+
+    // Trait implementation on a borrow.
+    impl ATrait for &MyInt {
+        // MyInt::method_on_borrow
+        fn method_on_borrow(&self) -> i64 {
+            (*(*self)).a // $ method=deref fieldof=MyInt
+        }
+
+        // MyInt::method_not_on_borrow
+        fn method_not_on_borrow(self) -> i64 {
+            (*self).a // $ method=deref fieldof=MyInt
+        }
+    }
+
     pub fn f() {
         let x1 = S(S2);
         println!("{:?}", x1.m1()); // $ method=m1
@@ -1128,10 +1151,21 @@ mod method_call_type_conversion {
         let t = x7.m1(); // $ method=m1 type=t:& type=t:&T.S2
         println!("{:?}", x7);
 
-        let x9 : String = "Hello".to_string(); // $ type=x9:String
+        let x9: String = "Hello".to_string(); // $ type=x9:String
+
         // Implicit `String` -> `str` conversion happens via the `Deref` trait:
         // https://doc.rust-lang.org/std/string/struct.String.html#deref.
         let u = x9.parse::<u32>(); // $ method=parse type=u:T.u32
+
+        let my_thing = &MyInt { a: 37 };
+        // implicit borrow of a `&`
+        let a = my_thing.method_on_borrow(); // $ MISSING: method=MyInt::method_on_borrow
+        println!("{:?}", a);
+
+        // no implicit borrow
+        let my_thing = &MyInt { a: 38 };
+        let a = my_thing.method_not_on_borrow(); // $ MISSING: method=MyInt::method_not_on_borrow
+        println!("{:?}", a);
     }
 }