Merge pull request #16885 from github/tausbn/python-fix-bad-join-in-f…

…unction-resolution-type-tracker

Python: Fix bad join in function resolution

python/ql/lib/semmle/python/frameworks/internal/PoorMansFunctionResolution.qll

@@ -22,9 +22,10 @@ private import semmle.python.dataflow.new.DataFlow
 /**
  * Gets the last decorator call for the function `func`, if `func` has decorators.
  */
-private Expr lastDecoratorCall(Function func) {
-  result = func.getDefinition().(FunctionExpr).getADecoratorCall() and
-  not exists(Call other_decorator | other_decorator.getArg(0) = result)
+pragma[nomagic]
+private DataFlow::TypeTrackingNode lastDecoratorCall(Function func) {
+  result.asExpr() = func.getDefinition().(FunctionExpr).getADecoratorCall() and
+  not exists(Call other_decorator | other_decorator.getArg(0) = result.asExpr())
 }
 
 /**
@@ -56,7 +57,7 @@ private DataFlow::TypeTrackingNode poorMansFunctionTracker(DataFlow::TypeTracker
     //
     // Note that this means that we blindly ignore what the decorator actually does to
     // the function, which seems like an OK tradeoff.
-    result.asExpr() = lastDecoratorCall(func)
+    result = pragma[only_bind_out](lastDecoratorCall(func))
   )
   or
   exists(DataFlow::TypeTracker t2 | result = poorMansFunctionTracker(t2, func).track(t2, t))