Look for callees through function variables

Author: owen-mc

ql/lib/semmle/go/dataflow/internal/DataFlowNodes.qll

@@ -470,6 +470,8 @@ module Public {
       exists(DataFlow::Node calleeSource | calleeSource = this.getACalleeSource() |
         result.asFuncLit() = calleeSource.asExpr()
         or
+        calleeSource = result.asFunction().getARead()
+        or
         exists(Method declared, Method actual |
           calleeSource = declared.getARead() and
           actual.implements(declared) and

ql/test/library-tests/semmle/go/dataflow/CallGraph/getACallee.expected

@@ -1,5 +1,4 @@
 missingCallee
-| test.go:58:2:58:8 | call to f | test.go:41:1:53:1 | function declaration |
 spuriousCallee
 | main.go:44:3:44:7 | call to m | main.go:17:1:17:17 | function declaration |
 | main.go:44:3:44:7 | call to m | main.go:21:1:21:20 | function declaration |

ql/test/library-tests/semmle/go/dataflow/CallGraph/viableCallee.expected

@@ -3,5 +3,4 @@ missingCallee
 | test.go:48:2:48:8 | call to f2 | test.go:17:1:20:1 | function declaration |
 | test.go:48:2:48:8 | call to f2 | test.go:36:1:39:1 | function declaration |
 | test.go:52:2:52:5 | call to f3 | test.go:11:1:11:28 | function declaration |
-| test.go:58:2:58:8 | call to f | test.go:41:1:53:1 | function declaration |
 spuriousCallee