Inconsistency between `HttpRequest` and `parse_file_upload` method introduced in 5.2.1

[g-as]

Bug report

What's wrong

#2654 removed BytesIO inheritance from HttpRequest which clashes with parse_file_upload signature.

    def parse_file_upload(
        self, META: Mapping[str, Any], post_data: BinaryIO
    )

A HttpRequest instance used to be allowed as a post_data value. But not anymore:

error: Argument 2 to "parse_file_upload" of "HttpRequest" has incompatible type "HttpRequest"; expected "BinaryIO"  [arg-type]

How is that should be

A HttpRequest instance should be a legitimate post_data value, as seen in HttpRequest._load_and_post_files method:

            if hasattr(self, "_body"):
                # Use already read data
                data = BytesIO(self._body)
            else:
                data = self
            try:
                self._post, self._files = self.parse_file_upload(self.META, data)
            except (MultiPartParserError, TooManyFilesSent):
                ...

System information

• OS: debian
• python 3.12
• django 5.2
• mypy 1.16.1
• django-stubs 5.2.1
• django-stubs-ext 5.2.1

[sobolevn]

PR is welcome :)

[UnknownPlatypus]

Maybe we should not have removed it from the inheritance ? It seem to cause more trouble?

[Tatsh]

Since HttpRequest only has a subset of BinaryIO, I think a protocol is in order so that anything implementing that minimal interface is passable, including HttpRequest.