add level PreCallGrapSteps to the callgraph

Author: erik-krogh

javascript/ql/src/semmle/javascript/dataflow/internal/CallGraphs.qll

@@ -4,6 +4,7 @@
 
 private import javascript
 private import semmle.javascript.dataflow.internal.StepSummary
+private import semmle.javascript.dataflow.internal.PreCallGraphStep
 
 cached
 module CallGraph {
@@ -48,6 +49,10 @@ module CallGraph {
     t.start() and
     AccessPath::step(function, result)
     or
+    t.start() and
+    imprecision = 0 and
+    PreCallGraphStep::step(any(DataFlow::Node n | function.flowsTo(n)), result)
+    or
     imprecision = 0 and
     exists(DataFlow::ClassNode cls |
       exists(string name |

javascript/ql/test/library-tests/CallGraphs/AnnotatedTest/reexport/a.js

@@ -0,0 +1,4 @@
+module.exports = {
+    /** name:reexport.foo */
+    foo: function foo() {}
+}

javascript/ql/test/library-tests/CallGraphs/AnnotatedTest/reexport/b.js

@@ -0,0 +1,7 @@
+const a = require("./a");
+
+module.exports = {
+    /** name:reexport.bar */
+    bar: function bar() {},
+    ...a
+}

javascript/ql/test/library-tests/CallGraphs/AnnotatedTest/reexport/import.js

@@ -0,0 +1,7 @@
+const b = require("./b.js");
+
+/** calls:reexport.foo */
+b.foo();
+
+/** calls:reexport.bar */
+b.bar();