Fix renderer ignore (#230)

* Require error codes for `type: ignore`

* Fix `type: ignore` of renderer variants

Based on:
https://mypy.readthedocs.io/en/stable/kinds_of_types.html#callable-types-and-lambdas

mypy can infer lambda types; it seems we just need to annotate the
lookup dict.

* Use `cast` instead of `Any`

This isn't necessary to pass mypy, but offers a little more clarity.

Co-authored-by: Dustin Ingram <di@users.noreply.github.com>

pyproject.toml

@@ -5,6 +5,11 @@ build-backend = "setuptools.build_meta:__legacy__"
 [tool.mypy]
 strict = true
 warn_unused_configs = true
+show_error_codes = true
+enable_error_code = [
+    "ignore-without-code"
+]
+
 [[tool.mypy.overrides]]
 # These modules do not yet have types available.
 module = [

readme_renderer/markdown.py

@@ -15,7 +15,7 @@
 
 import re
 import warnings
-from typing import Any, Match, Optional
+from typing import cast, Any, Dict, Callable, Match, Optional
 
 from html import unescape
 
@@ -33,13 +33,13 @@
 try:
     import cmarkgfm
     from cmarkgfm.cmark import Options as cmarkgfmOptions
-    variants = {
-        "GFM": lambda raw: cmarkgfm.github_flavored_markdown_to_html(
+    variants: Dict[str, Callable[[str], str]] = {
+        "GFM": lambda raw: cast(str, cmarkgfm.github_flavored_markdown_to_html(
             raw, options=cmarkgfmOptions.CMARK_OPT_UNSAFE
-        ),
-        "CommonMark": lambda raw: cmarkgfm.markdown_to_html(
+        )),
+        "CommonMark": lambda raw: cast(str, cmarkgfm.markdown_to_html(
             raw, options=cmarkgfmOptions.CMARK_OPT_UNSAFE
-        ),
+        )),
     }
 except ImportError:
     warnings.warn(_EXTRA_WARNING)
@@ -66,8 +66,7 @@ def render(
     if not renderer:
         return None
 
-    # The renderer is a lambda function, and mypy fails lambdas right now.
-    rendered = renderer(raw)  # type: ignore
+    rendered = renderer(raw)
 
     if not rendered:
         return None