Fix type annotations for django.utils.safestring (#179)

* Add/fix types for django.utils.safestring.mark_safe

Django code ref: 964dd4f4f2/django/utils/safestring.py (L71-L84)

* add generic annotations for mark_safe, remove SafeBytes as it is basically deprecated

Co-authored-by: Daniel Hahler <github@thequod.de>

django-stubs/utils/html.pyi

@@ -1,9 +1,7 @@
 from html.parser import HTMLParser
-from typing import Any, Dict, Iterator, List, Optional, Tuple, Union
+from typing import Any, Iterator, List, Optional, Tuple, Union
 
-from django.db.models.base import Model
+from django.utils.safestring import SafeText
-from django.db.models.fields.files import FieldFile
-from django.utils.safestring import SafeText, mark_safe as mark_safe
 
 TRAILING_PUNCTUATION_CHARS: str
 WRAPPING_PUNCTUATION: Any
@@ -13,15 +11,15 @@ word_split_re: Any
 simple_url_re: Any
 simple_url_2_re: Any
 
-def escape(text: Optional[Union[Model, FieldFile, int, str]]) -> SafeText: ...
+def escape(text: Any) -> SafeText: ...
-def escapejs(value: str) -> SafeText: ...
+def escapejs(value: Any) -> SafeText: ...
-def json_script(value: Union[Dict[str, str], str], element_id: str) -> SafeText: ...
+def json_script(value: Any, element_id: str) -> SafeText: ...
 def conditional_escape(text: Any) -> str: ...
 def format_html(format_string: str, *args: Any, **kwargs: Any) -> SafeText: ...
 def format_html_join(
     sep: str, format_string: str, args_generator: Union[Iterator[Any], List[Tuple[str]]]
 ) -> SafeText: ...
-def linebreaks(value: str, autoescape: bool = ...) -> str: ...
+def linebreaks(value: Any, autoescape: bool = ...) -> str: ...
 
 class MLStripper(HTMLParser):
     fed: Any = ...

django-stubs/utils/safestring.pyi

@@ -1,14 +1,26 @@
-from typing import Any
+from typing import TypeVar, overload, Callable, Any
+
+_SD = TypeVar("_SD", bound="SafeData")
 
 class SafeData:
-    def __html__(self) -> SafeText: ...
+    def __html__(self: _SD) -> _SD: ...
-
-class SafeBytes(bytes, SafeData):
-    def __add__(self, rhs: Any): ...
 
 class SafeText(str, SafeData):
+    @overload
+    def __add__(self, rhs: SafeText) -> SafeText: ...
+    @overload
     def __add__(self, rhs: str) -> str: ...
+    @overload
+    def __iadd__(self, rhs: SafeText) -> SafeText: ...
+    @overload
+    def __iadd__(self, rhs: str) -> str: ...
 
 SafeString = SafeText
 
-def mark_safe(s: Any) -> Any: ...
+_C = TypeVar("_C", bound=Callable)
+@overload
+def mark_safe(s: _SD) -> _SD: ...
+@overload
+def mark_safe(s: _C) -> _C: ...
+@overload
+def mark_safe(s: Any) -> SafeText: ...

test-data/typecheck/test_helpers.yml

@@ -39,4 +39,24 @@
         # Ensure that the method's type is preserved
         reveal_type(ClassWithAtomicMethod().atomic_method1) # N: Revealed type is 'def (abc: builtins.int) -> builtins.str'
         # Ensure that the method's type is preserved
-        reveal_type(ClassWithAtomicMethod().atomic_method3) # N: Revealed type is 'def (myparam: builtins.str) -> builtins.int'
+        reveal_type(ClassWithAtomicMethod().atomic_method3) # N: Revealed type is 'def (myparam: builtins.str) -> builtins.int'
+
+
+-   case: mark_safe_decorator_and_function
+    main: |
+        from django.utils.safestring import mark_safe
+        s = 'hello'
+        reveal_type(mark_safe(s))  # N: Revealed type is 'django.utils.safestring.SafeText'
+        reveal_type(mark_safe(s) + mark_safe(s))  # N: Revealed type is 'django.utils.safestring.SafeText'
+        reveal_type(s + mark_safe(s))  # N: Revealed type is 'builtins.str'
+
+        s += mark_safe(s)
+        reveal_type(s)  # N: Revealed type is 'builtins.str'
+        ms = mark_safe(s)
+        ms += mark_safe(s)
+        reveal_type(ms)  # N: Revealed type is 'django.utils.safestring.SafeText'
+
+        @mark_safe
+        def func(s: str) -> str:
+            pass
+        reveal_type(func)  # N: Revealed type is 'def (s: builtins.str) -> builtins.str'