Fix a bug in subprocess_overlay.

In the presence of an opaque *args or **kwargs, we don't know which overload of
subprocess.Popen.__new__ was matched.

PiperOrigin-RevId: 482882419

pytype/abstract/_pytd_function.py

@@ -338,11 +338,8 @@ def _can_match_multiple(self, args):
     for var in args.get_variables():
       if any(_isinstance(v, "AMBIGUOUS_OR_EMPTY") for v in var.data):
         return True
-    for arg in (args.starargs, args.starstarargs):
-      # An opaque *args or **kwargs behaves like an unknown.
-      if arg and not isinstance(arg, mixin.PythonConstant):
-        return True
-    return False
+    # An opaque *args or **kwargs behaves like an unknown.
+    return args.has_opaque_starargs_or_starstarargs()
 
   def _match_view(self, node, args, view, alias_map=None):
     if self._can_match_multiple(args):

pytype/abstract/function.py

@@ -629,6 +629,10 @@ def delete_namedarg(self, name):
   def replace(self, **kwargs):
     return attrs.evolve(self, **kwargs)
 
+  def has_opaque_starargs_or_starstarargs(self):
+    return any(arg and not _isinstance(arg, "PythonConstant")
+               for arg in (self.starargs, self.starstarargs))
+
 
 class ReturnValueMixin:
   """Mixin for exceptions that hold a return node and variable."""

pytype/overlays/subprocess_overlay.py

@@ -70,4 +70,7 @@ def _can_match_multiple(self, args):
       if not ambiguous:
         return False
       found_ambiguous_arg = True
-    return super()._can_match_multiple(args) if found_ambiguous_arg else False
+    if found_ambiguous_arg:
+      return super()._can_match_multiple(args)
+    else:
+      return args.has_opaque_starargs_or_starstarargs()

pytype/tests/test_stdlib2.py

@@ -506,6 +506,17 @@ def run1(value: bool) -> Any: ...
       def run2(value: Any) -> Union[bytes, str]: ...
     """)
 
+  def test_popen_kwargs(self):
+    self.Check("""
+      import subprocess
+      def popen(cmd: str, **kwargs):
+        kwargs['stdout'] = subprocess.PIPE
+        kwargs['stderr'] = subprocess.PIPE
+        process = subprocess.Popen(cmd, **kwargs)
+        stdout, _ = process.communicate()
+        assert_type(stdout, 'Union[bytes, str]')
+    """)
+
   def test_enum(self):
     self.Check("""
       import enum