Rule 14.3: Support conditonal expressions

Author: lcartey

c/misra/src/rules/RULE-14-3/ControllingExprInvariant.ql

@@ -57,8 +57,23 @@ where
       )
     ) and
     message = "Controlling expression in switch statement has invariant value."
+    or
+    exists(ConditionalExpr conditional |
+      conditional.getCondition() = expr and
+      (
+        conditionAlwaysFalse(expr) or
+        conditionAlwaysTrue(expr)
+      )
+    ) and
+    message = "Controlling expression in conditional statement has invariant value."
   ) and
   // Exclude cases where the controlling expressions is affected by a macro, because they can appear
   // invariant in a particular invocation, but be variant between invocations.
-  not expr.isAffectedByMacro()
+  not (
+    expr.isAffectedByMacro() and
+    // Permit boolean literal macros
+    not expr instanceof BooleanLiteral
+  ) and
+  // Exclude template variables, because they can be instantiated with different values.
+  not expr = any(TemplateVariable tv).getAnInstantiation().getAnAccess()
 select expr, message

c/misra/test/rules/RULE-14-3/ControllingExprInvariant.expected

@@ -3,3 +3,5 @@
 | test.c:16:9:16:13 | ... > ... | Controlling expression in if statement has invariant value. |
 | test.c:20:20:20:24 | ... < ... | Controlling expression in loop statement has invariant value. |
 | test.c:27:10:27:14 | ... < ... | Controlling expression in loop statement has invariant value. |
+| test.c:37:3:37:6 | 1 | Controlling expression in conditional statement has invariant value. |
+| test.c:38:3:38:3 | 1 | Controlling expression in conditional statement has invariant value. |

c/misra/test/rules/RULE-14-3/test.c

@@ -31,4 +31,10 @@ void f3() {
 void f4() {
   do {
   } while (0u == 1u); // COMPLIANT - by exception 2
+}
+
+void f5(bool b1) {
+  true ? 1 : 2; // NON_COMPLIANT
+  1 ? 1 : 2;    // NON_COMPLIANT
+  b1 ? 1 : 2;   // COMPLIANT
 }