Merge pull request #326 from rdmarsh2/rdmarsh/cpp/dead-code-goto

C++: new query for dead code after goto or break

cpp/ql/test/query-tests/Critical/DeadCodeGoto/DeadCodeGoto.expected

@@ -0,0 +1,3 @@
+| test.cpp:2:2:2:12 | goto ... | This statement makes $@ unreachable. | test.cpp:3:2:3:5 | ExprStmt | ExprStmt |
+| test.cpp:9:3:9:8 | break; | This statement makes $@ unreachable. | test.cpp:10:3:10:6 | ExprStmt | ExprStmt |
+| test.cpp:37:3:37:8 | break; | This statement makes $@ unreachable. | test.cpp:38:3:38:11 | return ... | return ... |

cpp/ql/test/query-tests/Critical/DeadCodeGoto/DeadCodeGoto.qlref

@@ -0,0 +1 @@
+Critical/DeadCodeGoto.ql

cpp/ql/test/query-tests/Critical/DeadCodeGoto/test.cpp

@@ -0,0 +1,83 @@
+int test1(int x) {
+	goto label; // BAD
+	x++;
+	label: return x;
+}
+
+int test2(int x) {
+	do {
+		break; // BAD
+		x++;
+	} while(false);
+	return x;
+}
+
+int test3(int x) {
+	goto label; // GOOD
+	label: x++;
+	return x;
+}
+
+int test4(int x) {
+	goto label; // GOOD
+	do {
+		label: x++;
+	} while(false);
+	return x;
+}
+
+int test5(int x, int y) {
+	switch(y) {
+	case 0:
+		break; // GOOD
+	case 1:
+		goto label; // GOOD
+		break;
+	case 2:
+		break; // BAD
+		return x;
+	case 3:
+		return x;
+		break; // GOOD
+	case 4:
+		goto label; // GOOD
+	case 5:
+		goto label;; // GOOD
+	default:
+		x++;
+	}
+	label:
+	return x;
+}
+
+void test6(int x, int cond) {
+	if (cond) {
+		x++;
+	} else goto end; // GOOD
+	x++;
+	end:
+}
+
+void test7(int x, int cond) {
+	if (cond)
+	{
+		goto target;
+	}
+	goto somewhere_else; // GOOD
+	while (x < 10) // not dead code
+	{
+	target:
+		x++;
+	}
+	somewhere_else:
+	switch (1)
+	{
+	  goto end;
+	  while (x < 10) // not dead code
+	  {
+	case 1:
+	    x++;
+	  } break;
+	}
+	end:
+}