Add control flow tests for "and" and "or" operators

test/libsolidity/syntaxTests/viewPureChecker/user_operator_with_pure_modifier.sol

@@ -0,0 +1,21 @@
+type Int is uint8;
+
+using {
+    add as +
+} for Int;
+
+function add(Int, Int) pure returns (Int) {
+    return Int.wrap(0);
+}
+
+function f() pure {
+    Int.wrap(0) + Int.wrap(1);
+}
+
+function g() {
+    Int.wrap(0) + Int.wrap(1);
+}
+
+
+// ----
+// Warning 2018: (178-225): Function state mutability can be restricted to pure

test/libsolidity/syntaxTests/viewPureChecker/user_operator_with_view_modifier.sol

@@ -0,0 +1,30 @@
+type Int is uint8;
+
+using {
+    add as +
+} for Int;
+
+
+function f_view() view {}
+
+function add(Int, Int) view returns (Int) {
+    f_view();
+    return Int.wrap(0);
+}
+
+function f() view {
+    Int.wrap(0) + Int.wrap(0);
+}
+
+function g() {
+    Int.wrap(0) + Int.wrap(0);
+}
+
+function h() pure {
+    Int.wrap(0) + Int.wrap(0);
+}
+
+
+// ----
+// Warning 2018: (220-267): Function state mutability can be restricted to view
+// TypeError 2527: (293-318): Function declared as pure, but this expression (potentially) reads from the environment or state and thus requires "view".