fix: Hook properly to MkDocs logging

With strict mode (`-s` option for build and serve
commands of MkDocs), the build should fail if any
warning has been issued.

This was not the case. This commit adds the
`warning_filter` counter declared and used by
MkDocs to loggers in all modules.

Reference: #86.

src/mkdocstrings/extension.py

@@ -22,7 +22,7 @@
       option_x: etc
 ```
 """
-
+import logging
 import re
 from typing import Tuple
 from xml.etree.ElementTree import XML, Element, ParseError  # nosec: we choose to trust the XML input
@@ -34,10 +34,13 @@
 from markdown.blockprocessors import BlockProcessor
 from markdown.extensions import Extension
 from markdown.util import AtomicString
-from mkdocs.utils import log
+from mkdocs.utils import warning_filter
 
 from .handlers import CollectionError, get_handler
 
+log = logging.getLogger(__name__)
+log.addFilter(warning_filter)
+
 
 def atomic_brute_cast(tree: Element) -> Element:
     """

src/mkdocstrings/handlers/python.py

@@ -5,15 +5,19 @@
 """
 
 import json
+import logging
 import os
 from subprocess import PIPE, Popen  # nosec: what other option, more secure that PIPE do we have? sockets?
 from typing import Optional
 
 from markdown import Markdown
-from mkdocs.utils import log
+from mkdocs.utils import warning_filter
 
 from . import BaseCollector, BaseHandler, BaseRenderer, CollectionError, DataType
 
+log = logging.getLogger(__name__)
+log.addFilter(warning_filter)
+
 
 class PythonRenderer(BaseRenderer):
     """

src/mkdocstrings/plugin.py

@@ -37,11 +37,14 @@
 from mkdocs.structure.files import Files
 from mkdocs.structure.pages import Page
 from mkdocs.structure.toc import AnchorLink
-from mkdocs.utils import log
+from mkdocs.utils import warning_filter
 
 from .extension import MkdocstringsExtension
 from .handlers import teardown
 
+log = logging.getLogger(__name__)
+log.addFilter(warning_filter)
+
 SELECTION_OPTS_KEY: str = "selection"
 """The name of the selection parameter in YAML configuration blocks."""
 RENDERING_OPTS_KEY: str = "rendering"