Remove 'RemovedInPytest4Warning'

src/_pytest/warning_types.py

@@ -103,16 +103,6 @@ class PytestUnknownMarkWarning(PytestWarning):
     __module__ = "pytest"
 
 
-class RemovedInPytest4Warning(PytestDeprecationWarning):
-    """
-    Bases: :class:`pytest.PytestDeprecationWarning`.
-
-    Warning class for features scheduled to be removed in pytest 4.0.
-    """
-
-    __module__ = "pytest"
-
-
 @attr.s
 class UnformattedWarning:
     """Used to hold warnings that need to format their message at runtime, as opposed to a direct message.

src/_pytest/warnings.py

@@ -4,8 +4,6 @@ from contextlib import contextmanager
 
 import pytest
 
-SHOW_PYTEST_WARNINGS_ARG = "-Walways::pytest.RemovedInPytest4Warning"
-
 
 def _setoption(wmod, arg):
     """
@@ -74,9 +72,6 @@ def catch_warnings_for_item(config, ihook, when, item):
             warnings.filterwarnings("always", category=DeprecationWarning)
             warnings.filterwarnings("always", category=PendingDeprecationWarning)
 
-        warnings.filterwarnings("error", category=pytest.RemovedInPytest4Warning)
-        warnings.filterwarnings("error", category=pytest.PytestDeprecationWarning)
-
         # filters should have this precedence: mark, cmdline options, ini
         # filters should be applied in the inverse order of precedence
         for arg in inifilters:

src/pytest.py

@@ -44,7 +44,7 @@ from _pytest.warning_types import PytestExperimentalApiWarning
 from _pytest.warning_types import PytestUnhandledCoroutineWarning
 from _pytest.warning_types import PytestUnknownMarkWarning
 from _pytest.warning_types import PytestWarning
-from _pytest.warning_types import RemovedInPytest4Warning
+
 
 set_trace = __pytestPDB.set_trace
 
@@ -84,7 +84,6 @@ __all__ = [
     "PytestWarning",
     "raises",
     "register_assert_rewrite",
-    "RemovedInPytest4Warning",
     "Session",
     "set_trace",
     "skip",