C++: Add support for UsingEntry.getEnclosingElement

Author: Matthew Gretton-Dann

cpp/ql/src/semmle/code/cpp/Element.qll

@@ -206,7 +206,8 @@ class Element extends ElementBase {
     namequalifiers(underlyingElement(this), unresolveElement(result), _, _) or
     initialisers(underlyingElement(this), unresolveElement(result), _, _) or
     exprconv(unresolveElement(result), underlyingElement(this)) or
-    param_decl_bind(underlyingElement(this),_,unresolveElement(result))
+    param_decl_bind(underlyingElement(this),_,unresolveElement(result)) or
+    using_container(unresolveElement(result),underlyingElement(this))
   }
 
   /** Gets the closest `Element` enclosing this one. */

cpp/ql/test/library-tests/usings/Usings2.expected

@@ -0,0 +1,7 @@
+| templates.cpp:9:5:9:14 | using c | file://:0:0:0:0 | std |
+| usings.cpp:8:1:8:11 | using nf | file://:0:0:0:0 | (global namespace) |
+| usings.cpp:9:1:9:17 | using namespace N | file://:0:0:0:0 | (global namespace) |
+| usings.cpp:18:3:18:13 | using bf | usings.cpp:16:8:16:8 | D |
+| usings.cpp:21:5:21:14 | using gf | usings.cpp:20:13:23:3 | { ... } |
+| usings.cpp:34:3:34:20 | using tbf | usings.cpp:32:8:32:9 | TD |
+| usings.cpp:42:5:42:22 | using foo | usings.cpp:41:11:41:15 | nsbar |

cpp/ql/test/library-tests/usings/Usings2.ql

@@ -0,0 +1,6 @@
+import cpp
+
+from UsingEntry ue, Element e
+where
+  e = ue.getEnclosingElement()
+select ue, e