TYP: fix ReadPickleBuffer (#48144)

* TYP: fix ReadPickleBuffer

* require fileno only for ReadCsvBuffer

* fix comment

* bump pyright

* pyright

Author: twoertwein

.pre-commit-config.yaml

@@ -102,7 +102,7 @@ repos:
         types: [python]
         stages: [manual]
         additional_dependencies: &pyright_dependencies
-        - pyright@1.1.264
+        - pyright@1.1.276
     -   id: pyright_reportGeneralTypeIssues
         # note: assumes python env is setup and activated
         name: pyright reportGeneralTypeIssues

pandas/_typing.py

@@ -198,10 +198,6 @@ def mode(self) -> str:
         # for _get_filepath_or_buffer
         ...
 
-    def fileno(self) -> int:
-        # for _MMapWrapper
-        ...
-
     def seek(self, __offset: int, __whence: int = ...) -> int:
         # with one argument: gzip.GzipFile, bz2.BZ2File
         # with two arguments: zip.ZipFile, read_sas
@@ -217,7 +213,7 @@ def tell(self) -> int:
 
 
 class ReadBuffer(BaseBuffer, Protocol[AnyStr_cov]):
-    def read(self, __n: int | None = ...) -> AnyStr_cov:
+    def read(self, __n: int = ...) -> AnyStr_cov:
         # for BytesIOWrapper, gzip.GzipFile, bz2.BZ2File
         ...
 
@@ -233,7 +229,7 @@ def flush(self) -> Any:
 
 
 class ReadPickleBuffer(ReadBuffer[bytes], Protocol):
-    def readline(self) -> AnyStr_cov:
+    def readline(self) -> bytes:
         ...
 
 
@@ -247,6 +243,10 @@ def __iter__(self) -> Iterator[AnyStr_cov]:
         # for engine=python
         ...
 
+    def fileno(self) -> int:
+        # for _MMapWrapper
+        ...
+
     def readline(self) -> AnyStr_cov:
         # for engine=python
         ...

pandas/io/common.py

@@ -50,6 +50,7 @@
     CompressionOptions,
     FilePath,
     ReadBuffer,
+    ReadCsvBuffer,
     StorageOptions,
     WriteBuffer,
 )
@@ -1106,6 +1107,9 @@ def _maybe_memory_map(
     if not memory_map:
         return handle, memory_map, handles
 
+    # mmap used by only read_csv
+    handle = cast(ReadCsvBuffer, handle)
+
     # need to open the file first
     if isinstance(handle, str):
         handle = open(handle, "rb")

pandas/io/xml.py

@@ -712,10 +712,7 @@ def get_data_from_filepath(
             storage_options=storage_options,
         ) as handle_obj:
             filepath_or_buffer = (
-                # error: Incompatible types in assignment (expression has type
-                # "Union[str, IO[str]]", variable has type "Union[Union[str,
-                # PathLike[str]], bytes, ReadBuffer[bytes], ReadBuffer[str]]")
-                handle_obj.handle.read()  # type: ignore[assignment]
+                handle_obj.handle.read()
                 if hasattr(handle_obj.handle, "read")
                 else handle_obj.handle
             )