Fix #604 - add test of template results

The modifications to the query to handle multiple copies of a
statement across different targets also support reporting of issues
across multiple template instantiations. This commit adds
additional tests to demonstrate that this works effectively.

Author: lcartey

cpp/common/test/rules/deadcode/DeadCode.expected

@@ -15,3 +15,5 @@
 | test.cpp:85:3:85:43 | declaration | This statement is dead code. |
 | test.cpp:87:3:87:30 | declaration | This statement is dead code. |
 | test.cpp:90:3:90:50 | declaration | This statement is dead code. |
+| test.cpp:108:3:108:21 | ExprStmt | This statement is dead code. |
+| test.cpp:120:3:120:23 | ExprStmt | This statement is dead code. |

cpp/common/test/rules/deadcode/test.cpp

@@ -91,3 +91,31 @@ int test_dead_code(int x) {
 
   return live5 + live6 + constexpr_used_array[1]; // COMPLIANT
 }
+
+class Foo {
+public:
+  void bar() { may_have_side_effects(); }
+};
+
+class Baz {
+public:
+  void bar() {} // No side effects
+};
+
+template <typename T> void test_template() {
+  T t;
+  t.bar();            // COMPLIANT
+  no_side_effects(1); // NON_COMPLIANT
+}
+
+template <typename T> void test_unused_template() {
+  T t;
+  t.bar(); // COMPLIANT
+  no_side_effects(
+      1); // NON_COMPLIANT[FALSE_NEGATIVE] - unused templates are not extracted
+}
+
+void test() {
+  test_template<Foo>();
+  test_template<Baz>(); // NON_COMPLIANT - template call has no affect
+}