Merge pull request github#13785 from owen-mc/go/change-golangSpecificParamArgFilter

Go: Avoid using getTarget() as it may not exist

Author: owen-mc

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

@@ -149,9 +149,10 @@ predicate golangSpecificParamArgFilter(
   // Interface methods calls may be passed strictly to that exact method's model receiver:
   arg.getPosition() != -1
   or
-  exists(Function callTarget | callTarget = call.getNode().(DataFlow::CallNode).getTarget() |
-    not isInterfaceMethod(callTarget)
-    or
-    callTarget = p.getCallable().asSummarizedCallable().asFunction()
-  )
+  p instanceof DataFlow::SummarizedParameterNode
+  or
+  not isInterfaceMethod(call.getNode()
+        .(DataFlow::CallNode)
+        .getACalleeWithoutVirtualDispatch()
+        .asFunction())
 }

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

@@ -489,13 +489,9 @@ module Public {
      * interface type.
      */
     Callable getACalleeIncludingExternals() {
-      result.asFunction() = this.getTarget()
+      result = this.getACalleeWithoutVirtualDispatch()
       or
       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
@@ -510,6 +506,19 @@ module Public {
      */
     FuncDef getACallee() { result = this.getACalleeIncludingExternals().getFuncDef() }
 
+    /**
+     * Gets the definition of a possible target of this call, excluding targets reachable via virtual dispatch.
+     */
+    Callable getACalleeWithoutVirtualDispatch() {
+      result.asFunction() = this.getTarget()
+      or
+      exists(DataFlow::Node calleeSource | calleeSource = this.getACalleeSource() |
+        result.asFuncLit() = calleeSource.asExpr()
+        or
+        calleeSource = result.asFunction().getARead()
+      )
+    }
+
     /**
      * Gets the name of the function, method or variable that is being called.
      *