Fix and enable Ruff lints PYI002, PYI026

These affect `rest_framework-stubs/compat.pyi` which is using some weird hacks that Ruff and mypy don't really like.

* PYI002: If test must be a simple comparison against sys.platform or sys.version_info
* PYI026: Use typing_extensions.TypeAlias for type aliases

pyproject.toml

@@ -39,10 +39,9 @@ ignore = ["PYI021", "PYI024", "PYI041", "PYI043"]
     "F405",
     "F822",
     "F821",
-    "PYI026",  # TODO fix these errors
     "PGH003",  # TODO fix these errors
-    "PYI002",  # TODO fix these errors
 ]
+"rest_framework-stubs/compat.pyi" = ["PYI042"]
 
 [tool.ruff.flake8-tidy-imports.banned-api]
 "_typeshed.Self".msg = "Use typing_extensions.Self (PEP 673) instead."

rest_framework-stubs/compat.pyi

@@ -1,51 +1,56 @@
 from typing import Any
 
 from django.db.models import QuerySet
+from typing_extensions import TypeAlias
 
 try:
     from django.contrib.postgres import fields as postgres_fields
 except ImportError:
-    postgres_fields = None  # type: ignore
+    postgres_fields: TypeAlias = None  # type: ignore[no-redef]
 try:
     import coreapi
 except ImportError:
-    coreapi = None
+    coreapi: TypeAlias = None  # type: ignore[no-redef]
 try:
     import uritemplate
 except ImportError:
-    uritemplate = None  # type: ignore
+    uritemplate: TypeAlias = None  # type: ignore[no-redef]
 try:
     import coreschema
 except ImportError:
-    coreschema = None
+    coreschema: TypeAlias = None  # type: ignore[no-redef]
 try:
     import yaml
 except ImportError:
-    yaml = None  # type: ignore
+    yaml: TypeAlias = None  # type: ignore[no-redef]
 try:
     import requests
 except ImportError:
-    requests = None  # type: ignore
+    requests: TypeAlias = None  # type: ignore[no-redef]
 try:
     import pygments
 except ImportError:
-    pygments = None
+    pygments: TypeAlias = None  # type: ignore[no-redef]
 try:
     import markdown
     def apply_markdown(text: str) -> str: ...
 
 except ImportError:
-    apply_markdown = None  # type: ignore
-    markdown = None  # type: ignore
+    apply_markdown: TypeAlias = None  # type: ignore[no-redef]
+    markdown: TypeAlias = None  # type: ignore[no-redef]
 
-if markdown is not None and pygments is not None:
+try:
+    import pygments
     from markdown.preprocessors import Preprocessor
 
     class CodeBlockPreprocessor(Preprocessor):
         pattern: Any
         formatter: Any
         def run(self, lines: list[str]) -> list[str]: ...
 
+except ImportError:
+    pass
+
 def pygments_css(style: Any) -> str | None: ...
 def pygments_highlight(text: str, lang: str, style: Any) -> Any: ...
 def md_filter_add_syntax_highlight(md: Any) -> bool: ...