C++: Document tests better

This addresses PR comments by @rdmarsh2.

Author: jbj

cpp/ql/test/library-tests/dataflow/fields/by_reference.cpp

@@ -66,5 +66,5 @@ void test_setThroughNonMember() {
 void test_nonMemberSetA() {
   S s;
   nonMemberSetA(&s, user_input());
-  sink(nonMemberGetA(&s)); // flow [NOT DETECTED due to lack of flow through &]
+  sink(nonMemberGetA(&s)); // flow
 }

cpp/ql/test/library-tests/dataflow/fields/flow.expected

@@ -219,7 +219,6 @@ edges
 | struct_init.c:26:23:29:3 | {...} [nestedAB, a] | struct_init.c:31:8:31:12 | outer [nestedAB, a] |
 | struct_init.c:26:23:29:3 | {...} [nestedAB, a] | struct_init.c:36:11:36:15 | outer [nestedAB, a] |
 | struct_init.c:26:23:29:3 | {...} [pointerAB, a] | struct_init.c:33:8:33:12 | outer [pointerAB, a] |
-| struct_init.c:26:23:29:3 | {...} [pointerAB, a] | struct_init.c:37:10:37:14 | outer [pointerAB, a] |
 | struct_init.c:27:5:27:23 | {...} [a] | struct_init.c:26:23:29:3 | {...} [nestedAB, a] |
 | struct_init.c:27:7:27:16 | call to user_input | struct_init.c:27:5:27:23 | {...} [a] |
 | struct_init.c:28:5:28:7 | & ... [a] | struct_init.c:26:23:29:3 | {...} [pointerAB, a] |
@@ -230,8 +229,12 @@ edges
 | struct_init.c:36:10:36:24 | & ... [a] | struct_init.c:14:24:14:25 | ab [a] |
 | struct_init.c:36:11:36:15 | outer [nestedAB, a] | struct_init.c:36:17:36:24 | nestedAB [a] |
 | struct_init.c:36:17:36:24 | nestedAB [a] | struct_init.c:36:10:36:24 | & ... [a] |
-| struct_init.c:37:10:37:14 | outer [pointerAB, a] | struct_init.c:37:16:37:24 | pointerAB [a] |
-| struct_init.c:37:16:37:24 | pointerAB [a] | struct_init.c:14:24:14:25 | ab [a] |
+| struct_init.c:40:17:40:36 | {...} [a] | struct_init.c:43:5:43:7 | & ... [a] |
+| struct_init.c:40:20:40:29 | call to user_input | struct_init.c:40:17:40:36 | {...} [a] |
+| struct_init.c:41:23:44:3 | {...} [pointerAB, a] | struct_init.c:46:10:46:14 | outer [pointerAB, a] |
+| struct_init.c:43:5:43:7 | & ... [a] | struct_init.c:41:23:44:3 | {...} [pointerAB, a] |
+| struct_init.c:46:10:46:14 | outer [pointerAB, a] | struct_init.c:46:16:46:24 | pointerAB [a] |
+| struct_init.c:46:16:46:24 | pointerAB [a] | struct_init.c:14:24:14:25 | ab [a] |
 nodes
 | A.cpp:41:15:41:21 | new | semmle.label | new |
 | A.cpp:43:10:43:12 | & ... | semmle.label | & ... |
@@ -495,8 +498,12 @@ nodes
 | struct_init.c:36:10:36:24 | & ... [a] | semmle.label | & ... [a] |
 | struct_init.c:36:11:36:15 | outer [nestedAB, a] | semmle.label | outer [nestedAB, a] |
 | struct_init.c:36:17:36:24 | nestedAB [a] | semmle.label | nestedAB [a] |
-| struct_init.c:37:10:37:14 | outer [pointerAB, a] | semmle.label | outer [pointerAB, a] |
-| struct_init.c:37:16:37:24 | pointerAB [a] | semmle.label | pointerAB [a] |
+| struct_init.c:40:17:40:36 | {...} [a] | semmle.label | {...} [a] |
+| struct_init.c:40:20:40:29 | call to user_input | semmle.label | call to user_input |
+| struct_init.c:41:23:44:3 | {...} [pointerAB, a] | semmle.label | {...} [pointerAB, a] |
+| struct_init.c:43:5:43:7 | & ... [a] | semmle.label | & ... [a] |
+| struct_init.c:46:10:46:14 | outer [pointerAB, a] | semmle.label | outer [pointerAB, a] |
+| struct_init.c:46:16:46:24 | pointerAB [a] | semmle.label | pointerAB [a] |
 #select
 | A.cpp:43:10:43:12 | & ... | A.cpp:41:15:41:21 | new | A.cpp:43:10:43:12 | & ... | & ... flows from $@ | A.cpp:41:15:41:21 | new | new |
 | A.cpp:49:13:49:13 | c | A.cpp:47:12:47:18 | new | A.cpp:49:13:49:13 | c | c flows from $@ | A.cpp:47:12:47:18 | new | new |
@@ -544,6 +551,7 @@ nodes
 | simple.cpp:29:12:29:12 | call to b | simple.cpp:42:12:42:21 | call to user_input | simple.cpp:29:12:29:12 | call to b | call to b flows from $@ | simple.cpp:42:12:42:21 | call to user_input | call to user_input |
 | struct_init.c:15:12:15:12 | a | struct_init.c:20:20:20:29 | call to user_input | struct_init.c:15:12:15:12 | a | a flows from $@ | struct_init.c:20:20:20:29 | call to user_input | call to user_input |
 | struct_init.c:15:12:15:12 | a | struct_init.c:27:7:27:16 | call to user_input | struct_init.c:15:12:15:12 | a | a flows from $@ | struct_init.c:27:7:27:16 | call to user_input | call to user_input |
+| struct_init.c:15:12:15:12 | a | struct_init.c:40:20:40:29 | call to user_input | struct_init.c:15:12:15:12 | a | a flows from $@ | struct_init.c:40:20:40:29 | call to user_input | call to user_input |
 | struct_init.c:22:11:22:11 | a | struct_init.c:20:20:20:29 | call to user_input | struct_init.c:22:11:22:11 | a | a flows from $@ | struct_init.c:20:20:20:29 | call to user_input | call to user_input |
 | struct_init.c:31:23:31:23 | a | struct_init.c:27:7:27:16 | call to user_input | struct_init.c:31:23:31:23 | a | a flows from $@ | struct_init.c:27:7:27:16 | call to user_input | call to user_input |
 | struct_init.c:33:25:33:25 | a | struct_init.c:20:20:20:29 | call to user_input | struct_init.c:33:25:33:25 | a | a flows from $@ | struct_init.c:20:20:20:29 | call to user_input | call to user_input |

cpp/ql/test/library-tests/dataflow/fields/struct_init.c

@@ -12,7 +12,7 @@ struct Outer {
 };
 
 void absink(struct AB *ab) {
-  sink(ab->a); // flow (three paths)
+  sink(ab->a); // flow (three sources)
   sink(ab->b); // no flow
 }
 
@@ -34,5 +34,14 @@ int struct_init(void) {
   sink(outer.pointerAB->b); // no flow
 
   absink(&outer.nestedAB);
+}
+
+int struct_init2(void) {
+  struct AB ab = { user_input(), 0 };
+  struct Outer outer = {
+    { user_input(), 0 },
+    &ab,
+  };
+
   absink(outer.pointerAB);
 }