Updates after code review

test/libsolidity/semanticTests/operators/custom/bind_function_that_shadows_keccak.sol

@@ -0,0 +1,16 @@
+type Int is int16;
+
+using {keccak256 as +} for Int;
+
+function keccak256(Int a, Int b) pure returns (Int) {
+    return Int.wrap(Int.unwrap(a) + Int.unwrap(b));
+}
+
+contract C {
+    function test() public returns (Int) {
+        return Int.wrap(3) + Int.wrap(4);
+    }
+}
+
+// ----
+// test() -> 7

test/libsolidity/semanticTests/operators/custom/function_bound_to_operator_as_global_and_non_global.sol

@@ -0,0 +1,30 @@
+==== Source: s1.sol ====
+type Int is int;
+
+using {add as +} for Int global;
+using {add as +} for Int;
+
+function add(Int a, Int b) pure returns (Int) {
+    return Int.wrap(Int.unwrap(a) + Int.unwrap(b));
+}
+
+function test_add() pure returns (Int) {
+    return Int.wrap(1) + Int.wrap(2);
+}
+
+==== Source: s2.sol ====
+import "s1.sol";
+
+contract C2 {
+    function test1() pure public returns (Int) {
+        return test_add();
+    }
+
+    function test2() pure public returns (Int) {
+        return Int.wrap(3) + Int.wrap(4);
+    }
+}
+
+// ----
+// test1() -> 3
+// test2() -> 7

test/libsolidity/semanticTests/operators/custom/global_unary_and_non_global_binary_operators_in_the_same_file.sol

@@ -0,0 +1,26 @@
+type Int is int16;
+
+using {unsub as -} for Int global;
+using {sub as -} for Int;
+
+function sub(Int a, Int b) pure returns (Int) {
+    return Int.wrap(Int.unwrap(a) - Int.unwrap(b));
+}
+
+function unsub(Int a) pure returns (Int) {
+    return Int.wrap(-Int.unwrap(a));
+}
+
+contract C {
+    function test_sub() public returns (Int) {
+        return Int.wrap(7) - Int.wrap(2);
+    }
+
+    function test_unsub() public returns (Int) {
+        return -Int.wrap(4);
+    }
+}
+
+// ----
+// test_sub() -> 5
+// test_unsub() -> -4