C++: Add a test with spurious flow.

Author: MathiasVP

cpp/ql/test/library-tests/dataflow/dataflow-tests/BarrierGuard.cpp

@@ -75,4 +75,13 @@ void bg_indirect_expr() {
   if (guarded(buf)) {
     sink(buf);
   }
-}
+}
+
+void test_guard_and_reassign() {
+  int x = source();
+
+  if(!guarded(x)) {
+    x = 0;
+  }
+  sink(x); // $ SPURIOUS: ast,ir
+}

cpp/ql/test/library-tests/dataflow/dataflow-tests/test-source-sink.expected

@@ -12,6 +12,7 @@ astFlow
 | BarrierGuard.cpp:60:11:60:16 | call to source | BarrierGuard.cpp:62:14:62:14 | x |
 | BarrierGuard.cpp:60:11:60:16 | call to source | BarrierGuard.cpp:64:14:64:14 | x |
 | BarrierGuard.cpp:60:11:60:16 | call to source | BarrierGuard.cpp:66:14:66:14 | x |
+| BarrierGuard.cpp:81:11:81:16 | call to source | BarrierGuard.cpp:86:8:86:8 | x |
 | acrossLinkTargets.cpp:19:27:19:32 | call to source | acrossLinkTargets.cpp:12:8:12:8 | x |
 | clang.cpp:12:9:12:20 | sourceArray1 | clang.cpp:18:8:18:19 | sourceArray1 |
 | clang.cpp:12:9:12:20 | sourceArray1 | clang.cpp:22:8:22:20 | & ... |
@@ -141,6 +142,7 @@ irFlow
 | BarrierGuard.cpp:49:10:49:15 | call to source | BarrierGuard.cpp:55:13:55:13 | x |
 | BarrierGuard.cpp:60:11:60:16 | call to source | BarrierGuard.cpp:64:14:64:14 | x |
 | BarrierGuard.cpp:60:11:60:16 | call to source | BarrierGuard.cpp:66:14:66:14 | x |
+| BarrierGuard.cpp:81:11:81:16 | call to source | BarrierGuard.cpp:86:8:86:8 | x |
 | acrossLinkTargets.cpp:19:27:19:32 | call to source | acrossLinkTargets.cpp:12:8:12:8 | x |
 | clang.cpp:12:9:12:20 | sourceArray1 | clang.cpp:18:8:18:19 | sourceArray1 |
 | clang.cpp:12:9:12:20 | sourceArray1 | clang.cpp:23:17:23:29 | *& ... |