C++: Add false positive.

Author: MathiasVP

cpp/ql/test/query-tests/Likely Bugs/Likely Typos/CompareWhereAssignMeant/CompareWhereAssignMeant.expected

@@ -6,3 +6,6 @@
 | test.cpp:39:23:39:28 | ... == ... | This '==' operator has no effect. The assignment ('=') operator was probably intended. |
 | test.cpp:42:23:42:28 | ... == ... | This '==' operator has no effect. The assignment ('=') operator was probably intended. |
 | test.cpp:51:13:51:13 | call to operator== | This '==' operator has no effect. The assignment ('=') operator was probably intended. |
+| test.cpp:71:18:71:23 | ... == ... | This '==' operator has no effect. The assignment ('=') operator was probably intended. |
+| test.cpp:72:3:72:8 | ... == ... | This '==' operator has no effect. The assignment ('=') operator was probably intended. |
+| test.cpp:73:3:73:12 | ... == ... | This '==' operator has no effect. The assignment ('=') operator was probably intended. |

cpp/ql/test/query-tests/Likely Bugs/Likely Typos/CompareWhereAssignMeant/test.cpp

@@ -61,3 +61,14 @@ template<typename T1, typename T2>
 auto sfinaeTrick(T1 x1, T2 x2) -> decltype(x1 == x2, bool()) { // GOOD
   return x1 == x2;
 }
+
+void report_error(const char*);
+
+#define DOES_NOT_THROW(E) do { try { E; } catch (...) { report_error(""); } } while(0)
+#define ID(X) (X)
+
+void test_inside_macro_expansion(int x, int y) {
+  DOES_NOT_THROW(x == y); // GOOD [FALSE POSITIVE]
+  x == y; // BAD
+  x == ID(y); // BAD
+}