C++: Use the new dataflow library in the 'missing scanf' query.

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

@@ -1,9 +1,8 @@
 | test.cpp:35:7:35:7 | i | This variable is read, but may not have been written. It should be guarded by a check that the $@ returns at least 1. | test.cpp:34:3:34:7 | call to scanf | call to scanf |
-| test.cpp:51:7:51:7 | i | This variable is read, but may not have been written. It should be guarded by a check that the $@ returns at least 1. | test.cpp:50:3:50:7 | call to scanf | call to scanf |
 | test.cpp:68:7:68:7 | i | This variable is read, but may not have been written. It should be guarded by a check that the $@ returns at least 1. | test.cpp:67:3:67:7 | call to scanf | call to scanf |
 | test.cpp:80:7:80:7 | i | This variable is read, but may not have been written. It should be guarded by a check that the $@ returns at least 1. | test.cpp:79:3:79:7 | call to scanf | call to scanf |
-| test.cpp:90:8:90:8 | i | This variable is read, but may not have been written. It should be guarded by a check that the $@ returns at least 1. | test.cpp:89:3:89:7 | call to scanf | call to scanf |
-| test.cpp:98:8:98:8 | i | This variable is read, but may not have been written. It should be guarded by a check that the $@ returns at least 1. | test.cpp:97:3:97:7 | call to scanf | call to scanf |
+| test.cpp:90:7:90:8 | * ... | This variable is read, but may not have been written. It should be guarded by a check that the $@ returns at least 1. | test.cpp:89:3:89:7 | call to scanf | call to scanf |
+| test.cpp:98:7:98:8 | * ... | This variable is read, but may not have been written. It should be guarded by a check that the $@ returns at least 1. | test.cpp:97:3:97:7 | call to scanf | call to scanf |
 | test.cpp:108:7:108:7 | i | This variable is read, but may not have been written. It should be guarded by a check that the $@ returns at least 1. | test.cpp:107:3:107:8 | call to fscanf | call to fscanf |
 | test.cpp:115:7:115:7 | i | This variable is read, but may not have been written. It should be guarded by a check that the $@ returns at least 1. | test.cpp:114:3:114:8 | call to sscanf | call to sscanf |
 | test.cpp:164:8:164:8 | i | This variable is read, but may not have been written. It should be guarded by a check that the $@ returns at least 1. | test.cpp:162:7:162:11 | call to scanf | call to scanf |
@@ -12,13 +11,9 @@
 | test.cpp:224:8:224:8 | j | This variable is read, but may not have been written. It should be guarded by a check that the $@ returns at least 2. | test.cpp:221:7:221:11 | call to scanf | call to scanf |
 | test.cpp:248:9:248:9 | d | This variable is read, but may not have been written. It should be guarded by a check that the $@ returns at least 2. | test.cpp:246:25:246:29 | call to scanf | call to scanf |
 | test.cpp:252:9:252:9 | d | This variable is read, but may not have been written. It should be guarded by a check that the $@ returns at least 2. | test.cpp:250:14:250:18 | call to scanf | call to scanf |
-| test.cpp:264:7:264:7 | i | This variable is read, but may not have been written. It should be guarded by a check that the $@ returns at least 1. | test.cpp:263:3:263:7 | call to scanf | call to scanf |
 | test.cpp:272:7:272:7 | i | This variable is read, but may not have been written. It should be guarded by a check that the $@ returns at least 1. | test.cpp:271:3:271:7 | call to scanf | call to scanf |
 | test.cpp:280:7:280:7 | i | This variable is read, but may not have been written. It should be guarded by a check that the $@ returns at least 1. | test.cpp:279:3:279:7 | call to scanf | call to scanf |
 | test.cpp:292:7:292:7 | i | This variable is read, but may not have been written. It should be guarded by a check that the $@ returns at least 1. | test.cpp:291:3:291:7 | call to scanf | call to scanf |
-| test.cpp:302:8:302:12 | ptr_i | This variable is read, but may not have been written. It should be guarded by a check that the $@ returns at least 1. | test.cpp:301:3:301:7 | call to scanf | call to scanf |
-| test.cpp:310:7:310:7 | i | This variable is read, but may not have been written. It should be guarded by a check that the $@ returns at least 1. | test.cpp:309:3:309:7 | call to scanf | call to scanf |
 | test.cpp:404:25:404:25 | u | This variable is read, but may not have been written. It should be guarded by a check that the $@ returns at least 1. | test.cpp:403:6:403:11 | call to sscanf | call to sscanf |
 | test.cpp:416:7:416:7 | i | This variable is read, but may not have been written. It should be guarded by a check that the $@ returns at least 1. | test.cpp:413:7:413:11 | call to scanf | call to scanf |
 | test.cpp:423:7:423:7 | i | This variable is read, but may not have been written. It should be guarded by a check that the $@ returns at least 1. | test.cpp:420:7:420:11 | call to scanf | call to scanf |
-| test.cpp:430:6:430:6 | i | This variable is read, but may not have been written. It should be guarded by a check that the $@ returns at least 1. | test.cpp:429:2:429:6 | call to scanf | call to scanf |

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

@@ -48,7 +48,7 @@ int main()
 		int i = 0;
 
 		scanf("%d", &i);
-		use(i); // BAD. Design choice: already initialized variables shouldn't make a difference.
+		use(i); // GOOD. Design choice: already initialized variables are fine.
 	}
 
 	{
@@ -261,7 +261,7 @@ int main()
 		i = 0;
 
 		scanf("%d", &i);
-		use(i); // BAD
+		use(i); // GOOD
 	}
 
 	{
@@ -269,7 +269,7 @@ int main()
 
 		set_by_ref(i);
 		scanf("%d", &i);
-		use(i); // BAD
+		use(i); // GOOD [FALSE POSITIVE]
 	}
 
 	{
@@ -277,7 +277,7 @@ int main()
 
 		set_by_ptr(&i);
 		scanf("%d", &i);
-		use(i); // BAD
+		use(i); // GOOD [FALSE POSITIVE]
 	}
 
 	{
@@ -299,7 +299,7 @@ int main()
 		int *ptr_i = &i;
 
 		scanf("%d", &i);
-		use(*ptr_i); // BAD: may not have written `i`
+		use(*ptr_i); // BAD [NOT DETECTED]: may not have written `i`
 	}
 
 	{
@@ -307,7 +307,7 @@ int main()
 		int *ptr_i = &i;
 
 		scanf("%d", ptr_i);
-		use(i); // BAD: may not have written `*ptr_i`
+		use(i); // BAD [NOT DETECTED]: may not have written `*ptr_i`
 	}
 
 	{
@@ -427,5 +427,5 @@ void scan_and_write() {
 void scan_and_static_variable() {
 	static int i;
 	scanf("%d", &i);
-	use(i);  // GOOD [FALSE POSITIVE]: static variables are always 0-initialized
+	use(i);  // GOOD: static variables are always 0-initialized
 }