Python: Remove unnecessary restriction from getNamedArgumentForCall

As agreed in #3407

Author: RasmusWL

python/ql/src/semmle/python/objects/ObjectAPI.qll

@@ -397,7 +397,6 @@ class CallableValue extends Value {
 
     /**
      * Gets the argument in `call` corresponding to the `name`d keyword parameter of this callable.
-     * ONLY WORKS FOR NON-BUILTINS.
      *
      * This method also gives results when the argument is passed as a positional argument in `call`, as long
      * as `this` is not a builtin function or a builtin method.
@@ -420,8 +419,7 @@ class CallableValue extends Value {
             PointsToInternal::pointsTo(call.getFunction(), _, called, _) and
             called.functionAndOffset(this, offset)
         |
-            call.getArgByName(name) = result and
-            exists(this.getParameterByName(name))
+            call.getArgByName(name) = result
             or
             exists(int n |
                 call.getArg(n) = result and

python/ql/test/library-tests/PointsTo/calls/getNamedArgumentForCall.expected

@@ -23,5 +23,9 @@
 | 42 | ControlFlowNode for Attribute() | Function C.n | arg1 | ControlFlowNode for IntegerLiteral |
 | 42 | ControlFlowNode for Attribute() | Function C.n | self | ControlFlowNode for c |
 | 42 | ControlFlowNode for Attribute() | Method(Function C.n, C()) | arg1 | ControlFlowNode for IntegerLiteral |
+| 46 | ControlFlowNode for open() | Builtin-function open | file | ControlFlowNode for Str |
+| 46 | ControlFlowNode for open() | Builtin-function open | mode | ControlFlowNode for Str |
 | 51 | ControlFlowNode for foo() | Function foo | a | ControlFlowNode for IntegerLiteral |
 | 55 | ControlFlowNode for bar() | Function bar | a | ControlFlowNode for IntegerLiteral |
+| 55 | ControlFlowNode for bar() | Function bar | b | ControlFlowNode for IntegerLiteral |
+| 55 | ControlFlowNode for bar() | Function bar | c | ControlFlowNode for IntegerLiteral |

python/ql/test/library-tests/PointsTo/calls/test.py

@@ -43,7 +43,7 @@ def foo(arg):
 
 # positional/keyword arguments for a builtin function
 open("foo.txt", "rb") # TODO: Not handled by getNamedArgumentForCall
-open(file="foo.txt", mode="rb") # TODO: Not handled by either getNamedArgumentForCall or getArgumentForCall
+open(file="foo.txt", mode="rb")
 
 # Testing how arguments to *args and **kwargs are handled
 def foo(a, *args):
@@ -52,4 +52,4 @@ def foo(a, *args):
 
 def bar(a, **kwargs):
     pass
-bar(a=1, b=2, c=3) # TODO: no result for `b` or `c` with getNamedArgumentForCall
+bar(a=1, b=2, c=3)