Move filter into meta finder

_distutils_hack/__init__.py

@@ -1,38 +1,19 @@
 # don't import any costly modules
 import sys
 import os
-import warnings
 
 
 is_pypy = '__pypy__' in sys.builtin_module_names
 
 
-class _TrivialRe:
-    def __init__(self, *patterns):
-        self._patterns = patterns
-
-    def match(self, string):
-        return all(pat in string for pat in self._patterns)
-
-
-# warnings.filterwarnings() imports the re module
-warnings._add_filter(
-    'ignore',
-    _TrivialRe("distutils", "deprecated"),
-    DeprecationWarning,
-    None,
-    0,
-    append=False
-)
-
-
 def warn_distutils_present():
     if 'distutils' not in sys.modules:
         return
     if is_pypy and sys.version_info < (3, 7):
         # PyPy for 3.6 unconditionally imports distutils, so bypass the warning
         # https://foss.heptapod.net/pypy/pypy/-/blob/be829135bc0d758997b3566062999ee8b23872b4/lib-python/3/site.py#L250
         return
+    import warnings
     warnings.warn(
         "Distutils was imported before Setuptools, but importing Setuptools "
         "also replaces the `distutils` module in `sys.modules`. This may lead "
@@ -45,6 +26,7 @@ def warn_distutils_present():
 def clear_distutils():
     if 'distutils' not in sys.modules:
         return
+    import warnings
     warnings.warn("Setuptools is replacing distutils.")
     mods = [
         name for name in sys.modules
@@ -89,6 +71,14 @@ def do_override():
         ensure_local_distutils()
 
 
+class _TrivialRe:
+    def __init__(self, *patterns):
+        self._patterns = patterns
+
+    def match(self, string):
+        return all(pat in string for pat in self._patterns)
+
+
 class DistutilsMetaFinder:
     def find_spec(self, fullname, path, target=None):
         if path is not None:
@@ -102,6 +92,17 @@ def spec_for_distutils(self):
         import importlib
         import importlib.abc
         import importlib.util
+        import warnings
+
+        # warnings.filterwarnings() imports the re module
+        warnings._add_filter(
+            'ignore',
+            _TrivialRe("distutils", "deprecated"),
+            DeprecationWarning,
+            None,
+            0,
+            append=True
+        )
 
         try:
             mod = importlib.import_module('setuptools._distutils')