From: Daniele Varrazzo <daniele.varrazzo@gmail.com>
Date: Fri, 4 Nov 2022 01:12:01 +0000 (+0100)
Subject: lint: fix type hints with disabled bytearray/memoryview/bytes equivalience
X-Git-Tag: pool-3.1.4~6
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5acb61464502dd7ca9ebd1c51b724ca472a4778d;p=thirdparty%2Fpsycopg.git

lint: fix type hints with disabled bytearray/memoryview/bytes equivalience

This changeset makes the code compatible with the current Mypy 0.981,
but passes most of the checks that Mypy 0.990 enforces if the byte
strings equivalence is disabled.
---

diff --git a/psycopg/psycopg/_struct.py b/psycopg/psycopg/_struct.py
index 5ccb7703b..191c4013d 100644
--- a/psycopg/psycopg/_struct.py
+++ b/psycopg/psycopg/_struct.py
@@ -12,9 +12,9 @@ from . import errors as e
 from ._compat import Protocol, TypeAlias
 
 PackInt: TypeAlias = Callable[[int], bytes]
-UnpackInt: TypeAlias = Callable[[bytes], Tuple[int]]
+UnpackInt: TypeAlias = Callable[[Buffer], Tuple[int]]
 PackFloat: TypeAlias = Callable[[float], bytes]
-UnpackFloat: TypeAlias = Callable[[bytes], Tuple[float]]
+UnpackFloat: TypeAlias = Callable[[Buffer], Tuple[float]]
 
 
 class UnpackLen(Protocol):
diff --git a/psycopg/psycopg/_transform.py b/psycopg/psycopg/_transform.py
index 86cce1913..0e9dcaf7a 100644
--- a/psycopg/psycopg/_transform.py
+++ b/psycopg/psycopg/_transform.py
@@ -194,7 +194,7 @@ class Transformer(AdaptContext):
 
         return out
 
-    def as_literal(self, obj: Any) -> Buffer:
+    def as_literal(self, obj: Any) -> bytes:
         dumper = self.get_dumper(obj, PY_TEXT)
         rv = dumper.quote(obj)
         # If the result is quoted, and the oid not unknown or text,
@@ -221,6 +221,8 @@ class Transformer(AdaptContext):
             if type_sql:
                 rv = b"%s::%s" % (rv, type_sql)
 
+        if not isinstance(rv, bytes):
+            rv = bytes(rv)
         return rv
 
     def get_dumper(self, obj: Any, format: PyFormat) -> "Dumper":
@@ -321,7 +323,7 @@ class Transformer(AdaptContext):
 
         return make_row(record)
 
-    def load_sequence(self, record: Sequence[Optional[bytes]]) -> Tuple[Any, ...]:
+    def load_sequence(self, record: Sequence[Optional[Buffer]]) -> Tuple[Any, ...]:
         if len(self._row_loaders) != len(record):
             raise e.ProgrammingError(
                 f"cannot load sequence of {len(record)} items:"
diff --git a/psycopg/psycopg/abc.py b/psycopg/psycopg/abc.py
index 1edde3db3..570a22363 100644
--- a/psycopg/psycopg/abc.py
+++ b/psycopg/psycopg/abc.py
@@ -51,8 +51,8 @@ PQGen: TypeAlias = Generator["Wait", "Ready", RV]
 
 # Adaptation types
 
-DumpFunc: TypeAlias = Callable[[Any], bytes]
-LoadFunc: TypeAlias = Callable[[bytes], Any]
+DumpFunc: TypeAlias = Callable[[Any], Buffer]
+LoadFunc: TypeAlias = Callable[[Buffer], Any]
 
 
 class AdaptContext(Protocol):
@@ -238,7 +238,7 @@ class Transformer(Protocol):
     ) -> Sequence[Optional[Buffer]]:
         ...
 
-    def as_literal(self, obj: Any) -> Buffer:
+    def as_literal(self, obj: Any) -> bytes:
         ...
 
     def get_dumper(self, obj: Any, format: PyFormat) -> Dumper:
@@ -250,7 +250,7 @@ class Transformer(Protocol):
     def load_row(self, row: int, make_row: "RowMaker[Row]") -> Optional["Row"]:
         ...
 
-    def load_sequence(self, record: Sequence[Optional[bytes]]) -> Tuple[Any, ...]:
+    def load_sequence(self, record: Sequence[Optional[Buffer]]) -> Tuple[Any, ...]:
         ...
 
     def get_loader(self, oid: int, format: pq.Format) -> Loader:
diff --git a/psycopg/psycopg/copy.py b/psycopg/psycopg/copy.py
index ff36431f9..1313a9a71 100644
--- a/psycopg/psycopg/copy.py
+++ b/psycopg/psycopg/copy.py
@@ -392,7 +392,7 @@ class QueuedLibpqDriver(LibpqWriter):
     def __init__(self, cursor: "Cursor[Any]"):
         super().__init__(cursor)
 
-        self._queue: queue.Queue[bytes] = queue.Queue(maxsize=QUEUE_SIZE)
+        self._queue: queue.Queue[Buffer] = queue.Queue(maxsize=QUEUE_SIZE)
         self._worker: Optional[threading.Thread] = None
         self._worker_error: Optional[BaseException] = None
 
@@ -599,7 +599,7 @@ class AsyncQueuedLibpqWriter(AsyncLibpqWriter):
     def __init__(self, cursor: "AsyncCursor[Any]"):
         super().__init__(cursor)
 
-        self._queue: asyncio.Queue[bytes] = asyncio.Queue(maxsize=QUEUE_SIZE)
+        self._queue: asyncio.Queue[Buffer] = asyncio.Queue(maxsize=QUEUE_SIZE)
         self._worker: Optional[asyncio.Future[None]] = None
 
     async def worker(self) -> None:
@@ -652,19 +652,19 @@ class Formatter(ABC):
         self._row_mode = False  # true if the user is using write_row()
 
     @abstractmethod
-    def parse_row(self, data: bytes) -> Optional[Tuple[Any, ...]]:
+    def parse_row(self, data: Buffer) -> Optional[Tuple[Any, ...]]:
         ...
 
     @abstractmethod
-    def write(self, buffer: Union[Buffer, str]) -> bytes:
+    def write(self, buffer: Union[Buffer, str]) -> Buffer:
         ...
 
     @abstractmethod
-    def write_row(self, row: Sequence[Any]) -> bytes:
+    def write_row(self, row: Sequence[Any]) -> Buffer:
         ...
 
     @abstractmethod
-    def end(self) -> bytes:
+    def end(self) -> Buffer:
         ...
 
 
@@ -676,7 +676,7 @@ class TextFormatter(Formatter):
         super().__init__(transformer)
         self._encoding = encoding
 
-    def parse_row(self, data: bytes) -> Optional[Tuple[Any, ...]]:
+    def parse_row(self, data: Buffer) -> Optional[Tuple[Any, ...]]:
         if data:
             return parse_row_text(data, self.transformer)
         else:
@@ -687,7 +687,7 @@ class TextFormatter(Formatter):
         self._signature_sent = True
         return data
 
-    def write_row(self, row: Sequence[Any]) -> bytes:
+    def write_row(self, row: Sequence[Any]) -> Buffer:
         # Note down that we are writing in row mode: it means we will have
         # to take care of the end-of-copy marker too
         self._row_mode = True
@@ -699,7 +699,7 @@ class TextFormatter(Formatter):
         else:
             return b""
 
-    def end(self) -> bytes:
+    def end(self) -> Buffer:
         buffer, self._write_buffer = self._write_buffer, bytearray()
         return buffer
 
@@ -721,7 +721,7 @@ class BinaryFormatter(Formatter):
         super().__init__(transformer)
         self._signature_sent = False
 
-    def parse_row(self, data: bytes) -> Optional[Tuple[Any, ...]]:
+    def parse_row(self, data: Buffer) -> Optional[Tuple[Any, ...]]:
         if not self._signature_sent:
             if data[: len(_binary_signature)] != _binary_signature:
                 raise e.DataError(
@@ -740,7 +740,7 @@ class BinaryFormatter(Formatter):
         self._signature_sent = True
         return data
 
-    def write_row(self, row: Sequence[Any]) -> bytes:
+    def write_row(self, row: Sequence[Any]) -> Buffer:
         # Note down that we are writing in row mode: it means we will have
         # to take care of the end-of-copy marker too
         self._row_mode = True
@@ -756,7 +756,7 @@ class BinaryFormatter(Formatter):
         else:
             return b""
 
-    def end(self) -> bytes:
+    def end(self) -> Buffer:
         # If we have sent no data we need to send the signature
         # and the trailer
         if not self._signature_sent:
@@ -828,17 +828,17 @@ def _format_row_binary(
     return out
 
 
-def _parse_row_text(data: bytes, tx: Transformer) -> Tuple[Any, ...]:
+def _parse_row_text(data: Buffer, tx: Transformer) -> Tuple[Any, ...]:
     if not isinstance(data, bytes):
         data = bytes(data)
-    fields = data.split(b"\t")
-    fields[-1] = fields[-1][:-1]  # drop \n
+    fields = data.split(b"\t")  # type: ignore
+    fields[-1] = fields[-1][:-1]  # type: ignore  # drop \n
     row = [None if f == b"\\N" else _load_re.sub(_load_sub, f) for f in fields]
     return tx.load_sequence(row)
 
 
-def _parse_row_binary(data: bytes, tx: Transformer) -> Tuple[Any, ...]:
-    row: List[Optional[bytes]] = []
+def _parse_row_binary(data: Buffer, tx: Transformer) -> Tuple[Any, ...]:
+    row: List[Optional[Buffer]] = []
     nfields = _unpack_int2(data, 0)[0]
     pos = 2
     for i in range(nfields):
diff --git a/psycopg/psycopg/generators.py b/psycopg/psycopg/generators.py
index 96a27d56f..37cba131a 100644
--- a/psycopg/psycopg/generators.py
+++ b/psycopg/psycopg/generators.py
@@ -20,7 +20,7 @@ from typing import List, Optional, Union
 
 from . import pq
 from . import errors as e
-from .abc import PipelineCommand, PQGen, PQGenConn
+from .abc import Buffer, PipelineCommand, PQGen, PQGenConn
 from .pq.abc import PGconn, PGresult
 from .waiting import Wait, Ready
 from ._compat import Deque
@@ -271,7 +271,7 @@ def copy_from(pgconn: PGconn) -> PQGen[Union[memoryview, PGresult]]:
     return result
 
 
-def copy_to(pgconn: PGconn, buffer: bytes) -> PQGen[None]:
+def copy_to(pgconn: PGconn, buffer: Buffer) -> PQGen[None]:
     # Retry enqueuing data until successful.
     #
     # WARNING! This can cause an infinite loop if the buffer is too large. (see
diff --git a/psycopg/psycopg/pq/abc.py b/psycopg/psycopg/pq/abc.py
index c59e43d59..9ee21c288 100644
--- a/psycopg/psycopg/pq/abc.py
+++ b/psycopg/psycopg/pq/abc.py
@@ -133,7 +133,7 @@ class PGconn(Protocol):
     def exec_params(
         self,
         command: bytes,
-        param_values: Optional[Sequence[Optional[bytes]]],
+        param_values: Optional[Sequence[Optional[Buffer]]],
         param_types: Optional[Sequence[int]] = None,
         param_formats: Optional[Sequence[int]] = None,
         result_format: int = Format.TEXT,
@@ -143,7 +143,7 @@ class PGconn(Protocol):
     def send_query_params(
         self,
         command: bytes,
-        param_values: Optional[Sequence[Optional[bytes]]],
+        param_values: Optional[Sequence[Optional[Buffer]]],
         param_types: Optional[Sequence[int]] = None,
         param_formats: Optional[Sequence[int]] = None,
         result_format: int = Format.TEXT,
@@ -161,7 +161,7 @@ class PGconn(Protocol):
     def send_query_prepared(
         self,
         name: bytes,
-        param_values: Optional[Sequence[Optional[bytes]]],
+        param_values: Optional[Sequence[Optional[Buffer]]],
         param_formats: Optional[Sequence[int]] = None,
         result_format: int = Format.TEXT,
     ) -> None:
@@ -178,7 +178,7 @@ class PGconn(Protocol):
     def exec_prepared(
         self,
         name: bytes,
-        param_values: Optional[Sequence[bytes]],
+        param_values: Optional[Sequence[Buffer]],
         param_formats: Optional[Sequence[int]] = None,
         result_format: int = 0,
     ) -> "PGresult":
@@ -225,7 +225,7 @@ class PGconn(Protocol):
     def notifies(self) -> Optional["PGnotify"]:
         ...
 
-    def put_copy_data(self, buffer: bytes) -> int:
+    def put_copy_data(self, buffer: Buffer) -> int:
         ...
 
     def put_copy_end(self, error: Optional[bytes] = None) -> int:
@@ -380,5 +380,5 @@ class Escaping(Protocol):
     def escape_bytea(self, data: Buffer) -> bytes:
         ...
 
-    def unescape_bytea(self, data: bytes) -> bytes:
+    def unescape_bytea(self, data: Buffer) -> bytes:
         ...
diff --git a/psycopg/psycopg/pq/pq_ctypes.py b/psycopg/psycopg/pq/pq_ctypes.py
index dccb0afbd..51462fea8 100644
--- a/psycopg/psycopg/pq/pq_ctypes.py
+++ b/psycopg/psycopg/pq/pq_ctypes.py
@@ -275,7 +275,7 @@ class PGconn:
     def exec_params(
         self,
         command: bytes,
-        param_values: Optional[Sequence[Optional[bytes]]],
+        param_values: Optional[Sequence[Optional["abc.Buffer"]]],
         param_types: Optional[Sequence[int]] = None,
         param_formats: Optional[Sequence[int]] = None,
         result_format: int = Format.TEXT,
@@ -292,7 +292,7 @@ class PGconn:
     def send_query_params(
         self,
         command: bytes,
-        param_values: Optional[Sequence[Optional[bytes]]],
+        param_values: Optional[Sequence[Optional["abc.Buffer"]]],
         param_types: Optional[Sequence[int]] = None,
         param_formats: Optional[Sequence[int]] = None,
         result_format: int = Format.TEXT,
@@ -329,7 +329,7 @@ class PGconn:
     def send_query_prepared(
         self,
         name: bytes,
-        param_values: Optional[Sequence[Optional[bytes]]],
+        param_values: Optional[Sequence[Optional["abc.Buffer"]]],
         param_formats: Optional[Sequence[int]] = None,
         result_format: int = Format.TEXT,
     ) -> None:
@@ -349,7 +349,7 @@ class PGconn:
     def _query_params_args(
         self,
         command: bytes,
-        param_values: Optional[Sequence[Optional[bytes]]],
+        param_values: Optional[Sequence[Optional["abc.Buffer"]]],
         param_types: Optional[Sequence[int]] = None,
         param_formats: Optional[Sequence[int]] = None,
         result_format: int = Format.TEXT,
@@ -364,7 +364,6 @@ class PGconn:
             aparams = (c_char_p * nparams)(
                 *(
                     # convert bytearray/memoryview to bytes
-                    # TODO: avoid copy, at least in the C implementation.
                     b
                     if b is None or isinstance(b, bytes)
                     else bytes(b)  # type: ignore[arg-type]
@@ -436,7 +435,7 @@ class PGconn:
     def exec_prepared(
         self,
         name: bytes,
-        param_values: Optional[Sequence[bytes]],
+        param_values: Optional[Sequence["abc.Buffer"]],
         param_formats: Optional[Sequence[int]] = None,
         result_format: int = 0,
     ) -> "PGresult":
@@ -447,7 +446,13 @@ class PGconn:
         alenghts: Optional[Array[c_int]]
         if param_values:
             nparams = len(param_values)
-            aparams = (c_char_p * nparams)(*param_values)
+            aparams = (c_char_p * nparams)(
+                *(
+                    # convert bytearray/memoryview to bytes
+                    b if b is None or isinstance(b, bytes) else bytes(b)
+                    for b in param_values
+                )
+            )
             alenghts = (c_int * nparams)(*(len(p) if p else 0 for p in param_values))
         else:
             nparams = 0
@@ -1050,13 +1055,15 @@ class Escaping:
         impl.PQfreemem(out)
         return rv
 
-    def unescape_bytea(self, data: bytes) -> bytes:
+    def unescape_bytea(self, data: "abc.Buffer") -> bytes:
         # not needed, but let's keep it symmetric with the escaping:
         # if a connection is passed in, it must be valid.
         if self.conn:
             self.conn._ensure_pgconn()
 
         len_out = c_size_t()
+        if not isinstance(data, bytes):
+            data = bytes(data)
         out = impl.PQunescapeBytea(
             data,
             byref(t_cast(c_ulong, len_out)),  # type: ignore[arg-type]
diff --git a/psycopg/psycopg/types/array.py b/psycopg/psycopg/types/array.py
index 5ecbac1fa..566f253c8 100644
--- a/psycopg/psycopg/types/array.py
+++ b/psycopg/psycopg/types/array.py
@@ -21,10 +21,10 @@ from .._typeinfo import TypeInfo
 
 _struct_head = struct.Struct("!III")  # ndims, hasnull, elem oid
 _pack_head = cast(Callable[[int, int, int], bytes], _struct_head.pack)
-_unpack_head = cast(Callable[[bytes], Tuple[int, int, int]], _struct_head.unpack_from)
+_unpack_head = cast(Callable[[Buffer], Tuple[int, int, int]], _struct_head.unpack_from)
 _struct_dim = struct.Struct("!II")  # dim, lower bound
 _pack_dim = cast(Callable[[int, int], bytes], _struct_dim.pack)
-_unpack_dim = cast(Callable[[bytes, int], Tuple[int, int]], _struct_dim.unpack_from)
+_unpack_dim = cast(Callable[[Buffer, int], Tuple[int, int]], _struct_dim.unpack_from)
 
 TEXT_ARRAY_OID = postgres.types["text"].array_oid
 
@@ -153,7 +153,7 @@ class ListDumper(BaseListDumper):
     _re_esc = re.compile(rb'(["\\])')
 
     def dump(self, obj: List[Any]) -> bytes:
-        tokens: List[bytes] = []
+        tokens: List[Buffer] = []
         needs_quotes = _get_needs_quotes_regexp(self.delimiter).search
 
         def dump_list(obj: List[Any]) -> None:
@@ -249,7 +249,7 @@ class ListBinaryDumper(BaseListDumper):
         if not obj:
             return _pack_head(0, 0, sub_oid)
 
-        data: List[bytes] = [b"", b""]  # placeholders to avoid a resize
+        data: List[Buffer] = [b"", b""]  # placeholders to avoid a resize
         dims: List[int] = []
         hasnull = 0
 
diff --git a/psycopg/psycopg/types/composite.py b/psycopg/psycopg/types/composite.py
index 36660e324..1c609c307 100644
--- a/psycopg/psycopg/types/composite.py
+++ b/psycopg/psycopg/types/composite.py
@@ -22,7 +22,7 @@ from .._encodings import _as_python_identifier
 _struct_oidlen = struct.Struct("!Ii")
 _pack_oidlen = cast(Callable[[int, int], bytes], _struct_oidlen.pack)
 _unpack_oidlen = cast(
-    Callable[[bytes, int], Tuple[int, int]], _struct_oidlen.unpack_from
+    Callable[[Buffer, int], Tuple[int, int]], _struct_oidlen.unpack_from
 )
 
 
@@ -33,7 +33,7 @@ class SequenceDumper(RecursiveDumper):
         if not obj:
             return start + end
 
-        parts = [start]
+        parts: List[Buffer] = [start]
 
         for item in obj:
             if item is None:
@@ -100,7 +100,7 @@ class BaseCompositeLoader(Loader):
         super().__init__(oid, context)
         self._tx = Transformer(context)
 
-    def _parse_record(self, data: bytes) -> Iterator[Optional[bytes]]:
+    def _parse_record(self, data: Buffer) -> Iterator[Optional[bytes]]:
         """
         Split a non-empty representation of a composite type into components.
 
@@ -163,7 +163,7 @@ class RecordBinaryLoader(Loader):
             )
         )
 
-    def _walk_record(self, data: bytes) -> Iterator[Tuple[int, int, int]]:
+    def _walk_record(self, data: Buffer) -> Iterator[Tuple[int, int, int]]:
         """
         Yield a sequence of (oid, offset, length) for the content of the record
         """
@@ -174,7 +174,7 @@ class RecordBinaryLoader(Loader):
             yield oid, i + 8, length
             i += (8 + length) if length > 0 else 8
 
-    def _config_types(self, data: bytes) -> None:
+    def _config_types(self, data: Buffer) -> None:
         oids = [r[0] for r in self._walk_record(data)]
         self._tx.set_loader_types(oids, self.format)
 
@@ -197,7 +197,7 @@ class CompositeLoader(RecordLoader):
             *self._tx.load_sequence(tuple(self._parse_record(data[1:-1])))
         )
 
-    def _config_types(self, data: bytes) -> None:
+    def _config_types(self, data: Buffer) -> None:
         self._tx.set_loader_types(self.fields_types, self.format)
 
 
diff --git a/psycopg/psycopg/types/datetime.py b/psycopg/psycopg/types/datetime.py
index 763a2340a..f0dfe83eb 100644
--- a/psycopg/psycopg/types/datetime.py
+++ b/psycopg/psycopg/types/datetime.py
@@ -22,12 +22,12 @@ if TYPE_CHECKING:
 
 _struct_timetz = struct.Struct("!qi")  # microseconds, sec tz offset
 _pack_timetz = cast(Callable[[int, int], bytes], _struct_timetz.pack)
-_unpack_timetz = cast(Callable[[bytes], Tuple[int, int]], _struct_timetz.unpack)
+_unpack_timetz = cast(Callable[[Buffer], Tuple[int, int]], _struct_timetz.unpack)
 
 _struct_interval = struct.Struct("!qii")  # microseconds, days, months
 _pack_interval = cast(Callable[[int, int, int], bytes], _struct_interval.pack)
 _unpack_interval = cast(
-    Callable[[bytes], Tuple[int, int, int]], _struct_interval.unpack
+    Callable[[Buffer], Tuple[int, int, int]], _struct_interval.unpack
 )
 
 utc = timezone.utc
diff --git a/psycopg/psycopg/types/hstore.py b/psycopg/psycopg/types/hstore.py
index ed47d0d2d..f1467db16 100644
--- a/psycopg/psycopg/types/hstore.py
+++ b/psycopg/psycopg/types/hstore.py
@@ -39,7 +39,7 @@ Hstore: TypeAlias = Dict[str, Optional[str]]
 
 
 class BaseHstoreDumper(RecursiveDumper):
-    def dump(self, obj: Hstore) -> bytes:
+    def dump(self, obj: Hstore) -> Buffer:
         if not obj:
             return b""
 
diff --git a/psycopg/psycopg/types/json.py b/psycopg/psycopg/types/json.py
index 9d090ef23..a80e0e4e3 100644
--- a/psycopg/psycopg/types/json.py
+++ b/psycopg/psycopg/types/json.py
@@ -15,7 +15,7 @@ from ..adapt import Buffer, Dumper, Loader, PyFormat, AdaptersMap
 from ..errors import DataError
 
 JsonDumpsFunction = Callable[[Any], str]
-JsonLoadsFunction = Callable[[Union[str, bytes, bytearray]], Any]
+JsonLoadsFunction = Callable[[Union[str, bytes]], Any]
 
 
 def set_json_dumps(
@@ -170,7 +170,7 @@ class _JsonLoader(Loader):
 
     def load(self, data: Buffer) -> Any:
         # json.loads() cannot work on memoryview.
-        if isinstance(data, memoryview):
+        if not isinstance(data, bytes):
             data = bytes(data)
         return self.loads(data)
 
@@ -195,7 +195,7 @@ class JsonbBinaryLoader(_JsonLoader):
         if data and data[0] != 1:
             raise DataError("unknown jsonb binary format: {data[0]}")
         data = data[1:]
-        if isinstance(data, memoryview):
+        if not isinstance(data, bytes):
             data = bytes(data)
         return self.loads(data)
 
diff --git a/psycopg/psycopg/types/multirange.py b/psycopg/psycopg/types/multirange.py
index 5846edcfa..7b9f54570 100644
--- a/psycopg/psycopg/types/multirange.py
+++ b/psycopg/psycopg/types/multirange.py
@@ -224,7 +224,7 @@ class MultirangeDumper(BaseMultirangeDumper):
         else:
             dump = fail_dump
 
-        out = [b"{"]
+        out: List[Buffer] = [b"{"]
         for r in obj:
             out.append(dump_range_text(r, dump))
             out.append(b",")
@@ -243,7 +243,7 @@ class MultirangeBinaryDumper(BaseMultirangeDumper):
         else:
             dump = fail_dump
 
-        out = [pack_len(len(obj))]
+        out: List[Buffer] = [pack_len(len(obj))]
         for r in obj:
             data = dump_range_binary(r, dump)
             out.append(pack_len(len(data)))
diff --git a/psycopg/psycopg/types/numeric.py b/psycopg/psycopg/types/numeric.py
index 48e096fa6..1bd9329f5 100644
--- a/psycopg/psycopg/types/numeric.py
+++ b/psycopg/psycopg/types/numeric.py
@@ -32,7 +32,7 @@ from .._wrappers import (
 
 
 class _IntDumper(Dumper):
-    def dump(self, obj: Any) -> bytes:
+    def dump(self, obj: Any) -> Buffer:
         t = type(obj)
         if t is not int:
             # Convert to int in order to dump IntEnum correctly
@@ -43,7 +43,7 @@ class _IntDumper(Dumper):
 
         return str(obj).encode()
 
-    def quote(self, obj: Any) -> bytes:
+    def quote(self, obj: Any) -> Buffer:
         value = self.dump(obj)
         return value if obj >= 0 else b" " + value
 
@@ -321,7 +321,7 @@ for i in range(DefaultContext.prec):
     _contexts[i] = DefaultContext
 
 _unpack_numeric_head = cast(
-    Callable[[bytes], Tuple[int, int, int, int]],
+    Callable[[Buffer], Tuple[int, int, int, int]],
     struct.Struct("!HhHH").unpack_from,
 )
 _pack_numeric_head = cast(
diff --git a/psycopg/psycopg/types/range.py b/psycopg/psycopg/types/range.py
index fb4c6e808..ade9b37ce 100644
--- a/psycopg/psycopg/types/range.py
+++ b/psycopg/psycopg/types/range.py
@@ -5,7 +5,7 @@ Support for range types adaptation.
 # Copyright (C) 2020 The Psycopg Team
 
 import re
-from typing import Any, Callable, Dict, Generic, Optional, TypeVar, Type, Tuple
+from typing import Any, Callable, Dict, Generic, List, Optional, TypeVar, Type, Tuple
 from typing import cast
 from decimal import Decimal
 from datetime import date, datetime
@@ -329,7 +329,7 @@ def dump_range_text(obj: Range[Any], dump: Callable[[Any], Buffer]) -> Buffer:
     if obj.isempty:
         return b"empty"
 
-    parts = [b"[" if obj.lower_inc else b"("]
+    parts: List[Buffer] = [b"[" if obj.lower_inc else b"("]
 
     def dump_item(item: Any) -> Buffer:
         ad = dump(item)
diff --git a/psycopg/psycopg/types/string.py b/psycopg/psycopg/types/string.py
index 5cd0d0e07..c15c3926a 100644
--- a/psycopg/psycopg/types/string.py
+++ b/psycopg/psycopg/types/string.py
@@ -78,11 +78,12 @@ class TextLoader(Loader):
     def load(self, data: Buffer) -> Union[bytes, str]:
         if self._encoding:
             if isinstance(data, memoryview):
-                return bytes(data).decode(self._encoding)
-            else:
-                return data.decode(self._encoding)
+                data = bytes(data)
+            return data.decode(self._encoding)
         else:
             # return bytes for SQL_ASCII db
+            if not isinstance(data, bytes):
+                data = bytes(data)
             return data
 
 
@@ -100,10 +101,10 @@ class BytesDumper(Dumper):
         super().__init__(cls, context)
         self._esc = Escaping(self.connection.pgconn if self.connection else None)
 
-    def dump(self, obj: bytes) -> Buffer:
+    def dump(self, obj: Buffer) -> Buffer:
         return self._esc.escape_bytea(obj)
 
-    def quote(self, obj: bytes) -> bytes:
+    def quote(self, obj: Buffer) -> bytes:
         escaped = self.dump(obj)
 
         # We cannot use the base quoting because escape_bytea already returns
@@ -148,14 +149,14 @@ class ByteaLoader(Loader):
             self.__class__._escaping = Escaping()
 
     def load(self, data: Buffer) -> bytes:
-        return bytes(self._escaping.unescape_bytea(data))
+        return self._escaping.unescape_bytea(data)
 
 
 class ByteaBinaryLoader(Loader):
 
     format = Format.BINARY
 
-    def load(self, data: Buffer) -> bytes:
+    def load(self, data: Buffer) -> Buffer:
         return data
 
 
diff --git a/psycopg_c/psycopg_c/_psycopg.pyi b/psycopg_c/psycopg_c/_psycopg.pyi
index a215eee58..0da2cab50 100644
--- a/psycopg_c/psycopg_c/_psycopg.pyi
+++ b/psycopg_c/psycopg_c/_psycopg.pyi
@@ -12,7 +12,6 @@ from typing import Any, Iterable, List, Optional, Sequence, Tuple
 from psycopg import pq
 from psycopg import abc
 from psycopg.rows import Row, RowMaker
-from psycopg.abc import PipelineCommand
 from psycopg.adapt import AdaptersMap, PyFormat
 from psycopg.pq.abc import PGconn, PGresult
 from psycopg.connection import BaseConnection
@@ -44,11 +43,13 @@ class Transformer(abc.AdaptContext):
     def dump_sequence(
         self, params: Sequence[Any], formats: Sequence[PyFormat]
     ) -> Sequence[Optional[abc.Buffer]]: ...
-    def as_literal(self, obj: Any) -> abc.Buffer: ...
+    def as_literal(self, obj: Any) -> bytes: ...
     def get_dumper(self, obj: Any, format: PyFormat) -> abc.Dumper: ...
     def load_rows(self, row0: int, row1: int, make_row: RowMaker[Row]) -> List[Row]: ...
     def load_row(self, row: int, make_row: RowMaker[Row]) -> Optional[Row]: ...
-    def load_sequence(self, record: Sequence[Optional[bytes]]) -> Tuple[Any, ...]: ...
+    def load_sequence(
+        self, record: Sequence[Optional[abc.Buffer]]
+    ) -> Tuple[Any, ...]: ...
     def get_loader(self, oid: int, format: pq.Format) -> abc.Loader: ...
 
 # Generators
@@ -58,7 +59,7 @@ def send(pgconn: PGconn) -> abc.PQGen[None]: ...
 def fetch_many(pgconn: PGconn) -> abc.PQGen[List[PGresult]]: ...
 def fetch(pgconn: PGconn) -> abc.PQGen[Optional[PGresult]]: ...
 def pipeline_communicate(
-    pgconn: PGconn, commands: Deque[PipelineCommand]
+    pgconn: PGconn, commands: Deque[abc.PipelineCommand]
 ) -> abc.PQGen[List[List[PGresult]]]: ...
 
 # Copy support
@@ -68,7 +69,7 @@ def format_row_text(
 def format_row_binary(
     row: Sequence[Any], tx: abc.Transformer, out: Optional[bytearray] = None
 ) -> bytearray: ...
-def parse_row_text(data: bytes, tx: abc.Transformer) -> Tuple[Any, ...]: ...
-def parse_row_binary(data: bytes, tx: abc.Transformer) -> Tuple[Any, ...]: ...
+def parse_row_text(data: abc.Buffer, tx: abc.Transformer) -> Tuple[Any, ...]: ...
+def parse_row_binary(data: abc.Buffer, tx: abc.Transformer) -> Tuple[Any, ...]: ...
 
 # vim: set syntax=python:
diff --git a/psycopg_c/psycopg_c/_psycopg/transform.pyx b/psycopg_c/psycopg_c/_psycopg/transform.pyx
index cfa01ca8a..48f338dd8 100644
--- a/psycopg_c/psycopg_c/_psycopg/transform.pyx
+++ b/psycopg_c/psycopg_c/_psycopg/transform.pyx
@@ -541,7 +541,7 @@ cdef class Transformer:
                 make_row, <PyObject *>record, NULL)
         return record
 
-    cpdef object load_sequence(self, record: Sequence[Optional[bytes]]):
+    cpdef object load_sequence(self, record: Sequence[Optional[Buffer]]):
         cdef Py_ssize_t nfields = len(record)
         out = PyTuple_New(nfields)
         cdef PyObject *loader  # borrowed RowLoader